John Deere YARD & GARDEN TRACTORS JOHN DEERE

JOHN DEERECONDENSED SPECIFICATIONS

Models 425 445 455

Engine Make Kawasaki Kawasaki Yanmar

Model FD620D FD620D 3TNA72UJ3

Bore 76 mm 76 mm 72 mm

(2.99 in.) (2.99 in.) (2.83 in.)

Stroke 68 mm 68 mm 72 mm

(2.68 in.) (2.68 in.) (2.83 in.)

Displacement 617 cc 617 cc 876 cc

(35.7 cu. in.) (35.7 cu. in.) (53.44 cu.in.)

Power Rating 14.9 kW 16.4 kW 16.4 kW

(20 hp) (22 hp) (22 hp)

Slow Idle 1450 rpm 1450 rpm 1650 rpm

High Speed (No-Load) 3550 rpm 3550 rpm 3350 rpm

Crankcase Capacity 1.5 L* 1.5 L* 2.8L*

(3.2 pt.) (3.2 pt.) (3 qt.)

Reduction Gear Capacity:

2-Wheel steering 5.6 L 5.6 L 5.6 L

(6 qt.) (6 qt.) (6 qt.)

4-Wheel steering 6.6 L 6.6 L 6.6 L

(7 qt.) (7 qt.) (7 qt.)

Cooling System Capacity 2.8 L 2.8 L 2.8 L

(3 qt.) (3 qt.) (3 qt.)

Fuel Tank Capacity 24.6 L 24.6 L 24.6 L

(6.5 gal.) (6.5 gal.) (6.5 gal.)

*Includes filter.

FRONT AXLE SYSTEM

FRONT WHEELS AND BEARINGS

Front wheels (2—Fig. JD7-1) may beremoved after detaching the retainingscrew (4). Front wheel bearings (1) arerenewable. Remove bearings using asuitable puller or press. Wheel bearingsare sealed and no additional lubricationis required.

STEERING SPINDLES

Lubrication

Lubricate the steering spindles afterevery 50 hours of operation. Inject goodquality EP grease into the fittings inthe outer ends of the axle.

Overhaul

To remove the steering spindles (6and 13—Fig. JD7-1), raise and supportthe front of the tractor. Remove thefront wheels. Disconnect tie rods (18)from the spindles as necessary. Remove

the snap ring (8) retaining the spindlein the axle, then lower the spindle fromthe axle main member.

Inspect the spindle bushings (7) forexcessive wear and replace when neces-sary. Install the spindle bushings so the

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John Deere YARD & GARDEN TRACTORS

Illustrations reproduced by permissionof Deere & Company. Copyright Deere & Company

Fig. JD7-1–Exploded view offront axle assembly used on2-wheel steer models.

1. Bearing2. Wheel hub3. Bearing4. Cap screw5. Cap6. Spindle, L.H.7. Bushings8. Snap ring9. Nut

10. Bushings11. Nut12. Axle main member13. Spindle, L.H.15. Bushing16. Flange screw17. Rod end18. Tie rod19. Rod end20. Pivot plate

gap between bushing flange and axleend is no more than 1mm (0.04 in.).

During assembly, tighten the tie rodretaining nut to 61 N·m (45 ft.-lb.). Lu-bricate the steering spindles by inject-ing EP grease into the grease fittings.

AXLE MAIN MEMBEROVERHAUL

To remove the front axle assembly,raise and support the front of the trac-tor. Remove the front wheels. On4-wheel-steer models, disconnect therear steering rod from the steeringplate (20—Fig. JD7-1). Detach thesteering cylinder from the steeringplate and axle.

NOTE: Steering cylinder may beremoved without disconnectingthe hydraulic hoses. The cylin-der end studs are tapered and aforked tool or soft-faced ham-mer may be required to dislodgethe end stud.

Support the axle, unscrew the pivotbolt (14—Fig. JD7-1), and remove theaxle (12).

Inspect the axle pivot bolt and bush-ings (10) for wear and replace whennecessary. Install the bushings flushwith the outer end of the axle bore.

To reinstall the axle, reverse the re-moval procedure. Be sure the guideplate on the frame fits behind the guidebolt (16) flange on each side. Tightenthe pivot bolt to 68 N·m (50 ft.-lb.).When installing the steering cylinder,be sure the guide pin in the cylinder fitsin the hole in the axle. On 4-wheel-steermodels, tighten the rear steering rodretaining nut to 170 N·m (125 ft.-lb.).

TIE RODS AND TOE-IN

Unscrew retaining nuts to removethe tie rods (18—Fig. JD7-1). The tierod ball joint ends (17 and 19) are re-placeable. Tighten the tie rod retainingnuts to 61 N·m (45 ft.-lb.).

The initial length of the tie rodshould be 292 mm (11.5 in.) on2-wheel-steering models or 313 mm(12.3 in.) on 4-wheel-steering models.Measure the tie rod length between thecenters of the rod end studs.

Accurate toe-in measurement is onlypossible with the front end of tractorunsupported and on level ground. Ro-tate the steering wheel so an 8 mmscrew can be inserted through thesteering plate hole (H—Fig. JD7-1) intothe hole in the front axle (12). Measurethe distance between the front wheelsat the front and rear of the wheels atthe hub height. The front distance mustbe 1-6 mm (0.04-0.24 in.) less than the

rear distance. To adjust toe-in, loosenthe tie rod end jam nuts and turn the tierods to adjust the tie rod length untilthe toe-in is 1-6 mm (0.04-0.24 in.). Thetie rods must be adjusted equally toprovide the correct turning radius ineach direction.

For proper steering operation on4-wheel-steer models, rear wheel toe-inshould be checked as described in theREAR-WHEEL STEERING SYSTEM.

FRONT

STEERING SYSTEM

All models may be equipped with a2-wheel-steering system, while Model425 may be equipped with a4-wheel-steering system. The frontwheel steering mechanism is similarfor all models. On the 4-wheel-steersystem, a rod attached to the frontsteering plate (20—Fig. JD7-1) trans-fers steering motion to the rear wheelsteering mechanism. Refer to theREAR STEERING SYSTEM section forrelated service information.

On all models, the hydrostatic driveunit supplies pressurized oil to a steer-ing control valve and cylinder to pro-vide power steering. Refer to theHYDROSTATIC TRANSMISSION sec-tion for maintenance and service infor-mation for the hydrostatic drive unit.

STEERING LEAKAGE TEST

The following test procedure willhelp identify and isolate internal leak-age in the steering control valve andcylinder.

Operate the tractor until hydraulicoil temperature is 110° F (43° C). Oper-ate all hydraulic components(transaxle, lift, etc.) so all hydraulic oilreaches the desired temperature. Turnthe wheels fully to the right. Stop theengine. Disconnect the outer return hy-draulic hose from the steering cylinderand cap the hose end. Start and run theengine at fast idle. Remove the steeringwheel cap. Using a torque wrench, ro-tate the steering wheel retaining nutclockwise at a constant torque of 6.8N·m (60 in.-lb.). Count the number ofturns in one minute while also checkingfor fluid leaking from the open cylinderport.

In one minute, no more than fourturns should be possible at the specifiedtorque. If excessive fluid exits the cylin-der port and more than four turns ispossible, then the cylinder is leaking in-ternally and should be replaced. If theexcessive cylinder leakage is not appar-ent, but more than four turns of thesteering wheel are possible, the control

valve is leaking internally and shouldbe repaired or replaced.

STEERING CYLINDEROVERHAUL

Mark the hydraulic hose locationsand disconnect the hoses. Disconnectthe steering cylinder at each end. Thecylinder end studs are tapered and aforked tool or soft-faced hammer maybe required to dislodge the end stud.

The steering cylinder is a welded as-sembly and must be replaced as an en-tire unit.

When installing the steering cylin-der, be sure the guide pin in the cylin-der fits in the hole in the axle. If thehoses are unmarked, connect the outerhose to the L-port on the steering con-trol valve and the inner hose to theR-port.

STEERING PLATE

Lubrication

Lubricate the steering plate after ev-ery 50 hours of operation. Inject EPgrease into grease fitting at the front ofthe axle.

Overhaul

To remove the steering plate(20—Fig. JD7-1), detach the tie rods(18) from the steering plate. On the4-wheel-steer models, detach the rearsteering rod from the steering plate. Onall models, remove the steering cylin-der without disconnecting the hydrau-lic hoses. Detach the cotter pin, removethe washer and unscrew the retainingnut (11). Remove the steering plate.

Inspect the bushings (15) and pivotstud. Install the bushings flush withthe outer surface of the axle bore. Re-verse disassembly to install the steer-ing plate. Tighten the retaining nutsecurely, but the plate should not bindwhen rotated. Install washers as re-quired to fill the gap between the nut(11) and cotter pin. Tighten tie rod re-taining nuts to 61 N·m (45 ft.-lb.). On4-wheel-steer models, tighten rearsteering rod retaining nut to 170 N·m(125 ft.-lb.).

STEERING COLUMNOVERHAUL

Remove the steering wheel cap(1—Fig. JD7-2), unscrew the retainingnut (2) and withdraw the steeringwheel (3). Raise the hood and removethe side panels. Remove the radiatorscreen. Remove the dash panel instru-ment module. Remove the choke con-trol knob, if so equipped, and thethrottle control knob, then remove the

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SERVICE MANUAL John Deere


boot. Disconnect the PTO switch wiringconnector.

To gain access to the lower dashpanel fasteners, remove the footrest.Remove the knobs on the hydraulic con-trol levers and remove the boot. Detachthe parking brake control rod. Discon-nect the light switch. On models soequipped, disconnect the cruise controllever. Unscrew the ignition switch re-taining nut. Unscrew the dash panelfasteners and remove the dash panel.Unscrew the steering column fastenersand remove the steering column (8) andshaft (12).

Inspect bushings (7) and replace ifexcessively worn. The steering shaft isavailable only as a unit assembly.

Reinstall the steering column andshaft by reversing the disassembly pro-cedure. Lightly lubricate the splinedend of the steering shaft with multipur-pose grease. Make certain the foamwasher (13) contacts the steering con-trol valve. Tighten the steering wheelnut to 38 N·m (28 ft.-lb.).

STEERING CONTROL VALVE

Removal and Installation

Raise the hood and remove the sidepanels. Drain coolant from the radiator.Disconnect the hydraulic lines to theradiator and drain the hydraulic fluidfrom the radiator. Disconnect the cool-ant hoses. Remove the radiator screenand coolant reservoir. Unscrew the fanshroud and move out of the way. Dis-connect the choke control cable, if soequipped, and throttle control cable.

Remove radiator mounting fastenersand remove the radiator. Mark the hy-draulic lines and hoses so they can bereinstalled in the proper position. Un-screw the retaining plate securing thelines and hoses to the control valve.Disconnect the lines and hoses from thecontrol valve. Unscrew the mountingscrew and remove the control valve.

Install the steering control valve byreversing the removal procedure.

Overhaul

An exploded view of the steering con-trol valve is shown in Fig. JD7-3. Priorto disassembly, thoroughly clean theoutside of the valve. Scribe a matchmark on the steering valve componentparts and valve body so that they can beinstalled in their original locations.

NOTE: The valve componentsare machined to extremely closetolerances. Use caution whendisassembling and reassem-bling to avoid scratching or nick-ing the valve components.

Thoroughly clean all parts priorto assembly.

To disassemble the control valve, re-move screws (24—Fig. JD7-3) and re-move components (15-23) from thevalve housing (2). Withdraw the spool(11) and sleeve (13) assembly from the

valve housing. Remove the thrust bear-ing assembly (7 and 8), and carefullyextract the seals (1 and 6) from thevalve housing.

NOTE: Springs (12) are undertension.

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Fig. JD7-2–Exploded view ofsteering column assembly.

1. Cap2. Nut3. Steering wheel4. Spring5. Snap ring6. Washer7. Bushing8. Steering column9. Spring

10. Tilt lever11. Cotter pin12. Steering shaft assy.13. Foam washer

Fig. JD7-3–Exploded view of power steering control valve.

1. Dust seal2. Housing3. Check ball4. O-ring5. Plug6. Quad seal

7. Thrust bearing8. Thrust race9. Collar

10. Snap ring11. Spool12. Leaf springs

13. Sleeve14. Pin15. O-ring16. Wear plate17. Drive shaft18. Spacer

19. Outer gear20. Inner gear21. O-ring22. Seal ring23. End cover24. Screw

Remove the pin (14) and separatesleeve (13) and spool (11). Carefully re-move the collar (9), which will releasethe spring leaves (12).

Inspect components for damage, in-cluding scratches, burrs and nicks. Aseal kit is available, otherwise, the con-trol valve must be serviced as a unit as-sembly.

Install a quad seal (6) using the fol-lowing procedure: Place one bearingrace (7) in the valve housing, then in-sert the sleeve (13) into the housing andhold the race tightly in the bore asshown in Fig. JD7-4. Install the quadseal (6) in the groove as shown. Removethe bearing race and sleeve.

Install the snap ring (10—Fig. JD7-3)on the spool (11). Insert two flat spring

leaves (12) in the spool slot. Then in-stall the remaining curved leaves, threeat a time, between the flat leaves. Posi-tion the collar (6) around the springs.Lubricate the spool with clean hydrau-lic oil and insert the spool in the sleeve(13). Position the springs into thenotches in the sleeve. Insert pin (14).

Install the dust seal (1) with the openside out. Lubricate the lips of the dustseal and quad seal with petroleum jelly.Lubricate and install the thrust bear-ing (7 and 8). Lubricate the spool as-sembly and carefully insert it into thehousing and through the seals.

Position the housing with the openside up in a vise. Only use sufficientclamping force to hold the housing ordamage may occur. Install the O-rings

(15) and wear plate (16). The holes inthe wear plate must match the holes inthe housing. Insert the drive shaft (17)so the notch engages the pin (14). In-stall the gerotor (19 and 20) so the holesmatch the wear plate holes. Install theremainder of components. Tighten theend cover retaining screws to 17 N·m(150 in.-lb.) in a crossing pattern.Tighten plug (5) to 17 N·m (150 in.-lb.).

REAR-WHEEL

STEERING SYSTEM

Models 425 and 455 may be equippedwith a 4-wheel steer system (see Fig.JD7-5). The front pivot plate (11) steer-ing motion provides directional forcefor the rear steering system. Linkagetransfers steering motion to the rearpivot plate (8). Tie rods connected be-tween the rear steering plate and steer-ing arms force the steering knuckles toturn in the desired direction.

When the front pivot plate is rotatedclockwise, the linkage moves the rearpivot plate counterclockwise. Thus, in aturn, the front and rear wheels pivot inopposite directions. This allows ashorter turning radius than can be ac-complished with front wheel steeringonly.

Refer to the FINAL DRIVE sectionfor service information concerningsteering knuckle and bearing assem-blies.

TIE RODS AND TOE-IN

Unscrew the retaining nuts to re-move the rear tie rods (23—Fig. JD7-5).Tighten the tie rod retaining nuts to45-57 N·m (33-42 ft.-lb.).

To check and adjust the rear wheeltoe-in, first adjust the toe-in of the frontwheels as previously outlined and leavethe 8 mm screw in the alignment holes(H—Fig. JD7-1) of the front pivot plateand front axle.

Insert a 10-mm screw through thealignment holes (H—Fig. JD7-5) of rearthe pivot plate (28) and mounting plate.It may be necessary to adjust the lengthof the middle link (4) by turning the ad-juster at the rear end of the link so thescrew can be inserted through thealignment hole (H) and mounting platehole. The alignment screws installed inthe front and rear pivot plates coordi-nates the front and rear wheel align-ment.

NOTE: The alignment screwmust be perpendicular to thepivot plate and mounting platewhen installed for proper toe-inalignment.

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Fig. JD7-4–Cross sectionalview showing assembly ofsleeve (13), quad seal (6)and bearing race (7). Seetext.

Fig. JD7-5–Drawing of 4-wheel steering components.

1. Steering wheel2. Tilt steering assy.3. Steering column4. Drag link5. Front pivot housing6. Front steering arm7. Front steering link8. Tie rod9. Front axle

10. Steering cylinder11. Front pivot plate

12. Tie rod13. Front spindle14. Left turn hose15. Right turn hose16. Return port17. Left turn port18. Right turn port19. Inlet port20. Steering valve21. Rear pivot arm

22. Rear link23. Rear tie rod24. Rear spindle housing25. Rear hub26. Rear spindle plate27. Rear axle28. Rear pivot plate29. Rear tie rod30. Rear spindle plate31. Rear pivot housing

Toe-in of rear wheels should be zero(front distance equal to rear distance).Adjust toe-in by loosening the jam nutsand rotating the adjusting nut on eachtie rod (23—Fig. JD7-5). Note the innerjam nut has left-hand threads. Be surethe tie rods are adjusted equally tomaintain the proper wheel alignment.

STEERING ARMPIVOTS AND LINKS

Refer to Fig. JD7-5 for the diagramshowing the location of front and rearsteering arm pivot assemblies (5 and31) and connecting links (7 and 22).

NOTE: Do not attempt to rotaterod ends on intermediate links (7and 22). The rod ends arepeened to lock them in place.Link length is not adjustable.

Exploded views of pivot assembliesare shown in Figs. JD7-6 and JD7-7.Unscrew retaining nut and detach thesnap ring to remove the steering armfrom the pivot housing.

Inspect components for wear and re-place when necessary. During assem-bly, tighten the retaining nut to 108N·m (80 ft.-lb.). Tighten pivot housingmounting bolts to 84 N·m (62 ft.-lb.).

REAR PIVOT ASSEMBLY

Refer to Figs. JD7-8 and JD7-9 for anexploded view and cross-section of therear pivot assembly. To remove thepivot assembly, disconnect tie rods andsteering arm link from the pivot plate(4). Remove the cap screws attachingthe pivot bracket (1) to the frame andlower the assembly from the tractor.

Working through the access holes(A—Fig. JD7-9) in pivot plate, pry thecap (12) from the bottom of pivot plate(4). Use a punch through the accessholes to drive the spring pin (11) out ofthe retaining nut (10). Remove the nutand withdraw the pivot plate assemblyfrom the pivot bracket stub shaft. Prythe seal (2) from the pivot plate.

Inspect components for wear and re-place when necessary. When assem-bling the rear pivot assembly, installthe seal (2) so the open side is up andthe seal is flush with the top of the bore.Pack bearings with EP grease prior toinstallation. While tightening the nut(10) to 67-83 N·m (49-61 ft.-lb.), alignthe slot in the nut with the pin hole inthe pivot stud. Insert the spring pin(11). Install the cap (12), then fill thecavity with EP grease through thegrease fitting.

ENGINE

MAINTENANCE

Lubrication

Models 425 and 445

The engine oil level should bechecked prior to operating the engine.Check the oil level with the oil cap notscrewed in, but just touching the firstthreads.

The recommended oil is any pre-mium grade oil meeting the latest APIservice classification. Use oil viscositybased on the expected ambient temper-ature range during the period betweenoil changes as indicated in the chartshown in Fig. JD7-10.

Change the oil after the first fivehours of operation and then after every50 hours of operation, or more fre-quently when operation is severe.Change the oil filter, on engines soequipped, after the first five hours ofoperation and then after every 100hours of operation.

An oil pressure switch on the engineactivates the dash panel warning light.

Model 455

Engine oil level should be checkedprior to operating engine. Maintain theoil level between the F (full) mark andthe L (low) mark on the dipstick.

The recommended engine lubricanthas the API classification CD. Select oil

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Fig. JD7-6–Exploded view of rear steeringpivot.

1. Pivot arm2. Pivot housing3. Bearing

4. Spacer5. Snap ring6. Nut

Fig. JD7-7–Exploded view of front steeringpivot.

1. Nut2. Snap ring3. Bearings

4. Spacer5. Pivot housing6. Pivot arm

Fig. JD7-8–Exploded view of rear steeringpivot plate assembly.

1. Pivot support2. Seal3. Bearing4. Pivot plate5. Grease fitting6. Tie rod

7. Washer8. Snap ring9. Washer

10. Nut11. Roll pin12. Cap

Fig. JD7-9–Cross-sectional drawing of rearpivot plate assembly. Small holes (A) arelocated in the pivot plate hub to provide ac-cess for removal of cap (12) and roll pin(11). Refer to Fig. JD7-8 for parts identifica-tion.

viscosity based on the expected ambi-ent temperature range as shown ontemperature chart in Fig. JD7-10.

The recommended oil change inter-val is after every 200 hours of use. Theoil filter is a spin-on paper element car-tridge. On new and reconditioned en-gines, lubricating oil and filter shouldbe changed after the first 50 hours ofoperation.

Air Filter

Models 425 and 445

The engine is equipped with a dry airfilter. Clean or change the filter whenthe air restriction indicator’s yellowplunger reaches the red line.

Remove foam and paper air filter ele-ments from the air filter housing. Thefoam element should be washed in amild detergent and water solution,rinsed in clean water and allowed to air

dry. Soak the foam element in clean en-gine oil. Squeeze out excess oil.

The paper element cannot be cleanedand must be replaced when dirty. Rein-stall filter elements.

Model 455

The tractor is equipped with an outerprimary filter element and an innersafety element. The primary filter ele-ment should be removed and cleanedafter every 200 hours of operation ormore frequently when operating in ex-tremely dusty conditions. Remove dustfrom the filter element by tappinglightly with your hand, not on a hardsurface. Compressed air at pressureunder 30 psi (210 kPa) may also be di-rected inside the filter element, but becareful not to damage the element. Donot wash the air filter element. Replacethe filter once a year or more often ifdamaged or extremely dirty.

The inner filter element should notbe cleaned. If contaminants are evidenton the inner filter, the outer filter hasfailed and both filters should be re-placed.

Cooling System

Periodically clean debris from the ra-diator screen and check the radiator’scoolant level.

WARNING: The cooling systemis pressurized. Remove the radi-ator cap only when the engine iscold.

Periodically inspect the coolanthoses. Replace damaged or deterio-rated hoses.

Coolant system capacity is approxi-mately 2.8 liters (3.0 qt.). The recom-mended coolant is a 50/50 mixture ofclean water and permanent antifreeze.The antifreeze must be suitable for usein aluminum engines.

Flush the cooling system after every12 months.

A thermostat maintains cooling sys-tem temperature. On Models 425 and445, the thermostat should begin toopen at 63-66°C (145-150°F) and openfully at 80°C (176°F). On Model 455, thethermostat should begin to open at71°C (160°F) and be fully open at 82°C(180°F). A coolant temperature sensoron the engine controls the dash panelgauge.

Spark Plug(Models 425 and 445)

The recommended spark plug is NGKBMR4A for Model 425 and NGKBMR6A for Model 445. The spark pluggap should be 0.76 mm (0.030 in.).Tighten the spark plug to 20 N·m (177in.-lb.).

Fuel Filter

Model 425

The fuel filter (2—Fig. JD7-11)should be replaced after every 250hours or operation or annually, which-ever comes first. Stop the engine and letit cool before removing the filter.

Close the fuel shut-off valve (3).Squeeze the hose clamps and discon-nect fuel hoses from the filter. Installthe new filter with the arrow on the fil-ter housing pointing in the direction ofthe fuel flow.

Model 445

The fuel filter should be replaced af-ter every 500 hours of operation.

NOTE: Fuel system pressuremust be relieved before perform-ing any service to the fuel injec-tion system.

To relieve fuel pressure, first stop theengine and let it cool. Open the fueltank cap to relieve pressure in the fueltank. Raise the hood and remove theside panel from right side. Loosen thefuel pressure relief screw (2—Fig.JD7-12) one-half turn counterclockwiseto relieve the fuel pressure in system.

The fuel filter (1) is located under theplatform on right side of tractor.Squeeze the two clips to disconnect fuelhoses from the filter. Remove thescrews attaching the filter to the frameand remove the filter. Install the newfilter so the arrow on the filter housingis pointing in the direction of the fuelflow. Tighten the fuel pressure reliefscrew.

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Fig. JD7-10–Chart showing recommendedoil viscosity for ambient temperature.

Fig. JD7-11–Drawing of Model 425 fuel sys-tem showing carburetor (1), fuel filter (2)and fuel shut-off valve (3). The carburetorvent solenoid (4) stops fuel flow to the en-gine when de-energized.

Fig. JD7-12–Drawing of Model 445 fuel sys-tem showing location of fuel filter (1) andfuel pressure relief screw (2).

Model 455

A replaceable paper element fuel fil-ter (7—Fig. JD7-13) is located betweenthe fuel feed pump and fuel injectionpump. Water and sediment should bedrained from the filter bowl (11) afterevery 50 hours of operation or whennecessary. To drain water, unscrew theretaining ring (12) and remove the bowland filter assembly. If an unusualamount of water or sediment is evident,locate the source of contamination andcorrect it. Clean the filter bowl and in-stall filter assembly.

The filter element should be replacedannually or sooner if the loss of enginepower is evident. Air must be bled fromthe system after installing the filter.

Bleed Fuel System. Air must bebled from the diesel fuel system any-time the fuel lines are disconnected ora fuel system component is removed.To bleed air from fuel system, firstloosen the bleed screw (1—Fig.JD7-13) on the filter housing. Turn thekey switch ON to activate the fuel feedpump. When air-free fuel flows fromthe bleed screw, tighten the screw.Loosen the bleed screw on the fuel in-jection pump fuel inlet fitting. Whenair-free fuel flows from the bleed screw,tighten the screw and turn the keyswitch OFF. If the engine will notstart, loosen the fuel injector line fit-tings at the injectors and crank the en-gine until the fuel flows from all lines.Tighten the injector line fittings andstart the engine.

Engine Control Cables(Models 425 and 445)

Adjust the throttle control cable asfollows: Loosen the throttle cable clamp(1—Fig. JD7-14) at the engine end.Move the throttle lever on the instru-ment panel towards the fast idle untilthe throttle lever arm at the cable endis 2-3 mm (0.08-0.12 in.) from the ped-estal opening edge. Pull the throttle ca-ble housing so the control lever (3) atthe engine end is against the end of theslot (4) in the plate. Retighten theclamp. Check the throttle for a fullrange of movement without binding.

On Model 425, loosen the choke cablehousing clamp (2—Fig. JD7-14) and ad-just the position of the cable housing sothe choke carburetor plate operatesthrough the full range.

To adjust the maximum unloadedengine speed (fast idle), run the enginewith the throttle control lever in themaximum speed position. Using an ac-curate tachometer, check the enginerpm. The engine speed should be3450-3650 rpm. Loosen the controlplate retaining screws (5—Fig.

JD7-14) and move the control plate (6)to adjust the fast idle speed. Retightenscrews.

Throttle Control Cable(Model 455)

The throttle hand lever should movesmoothly, but have enough tension tomaintain throttle setting. To adjustthrottle friction, turn the adjusting nutlocated on the hand lever quadrantclockwise to increase tension or coun-

terclockwise to decrease the tensionsetting.

Throttle cable should be adjusted sothe governor lever on injection pumpmoves fully to the slow and fast idle po-sitions. To adjust, loosen the throttlecable clamp (C—Fig. JD7-15) locatedadjacent to the injection pump. Movethe hand lever towards the fast idle po-sition until the cable end of the lever is2-3 mm (0.080-0.120 in.) away from theend of the slot in the frame. While hold-ing the throttle control lever against

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Fig. JD7-13–Exploded view of fuel filter forModel 455.

1. Bleed screw2. Filter housing3. Shutoff valve4. O-ring5. Spring6. Knob7. Filter element8. O-ring9. Spring

10. Gasket11. Fuel bowl12. Retaining ring

Fig. JD7-14–Adjust throttleand choke control wires asdescribed in text.

1. Throttle cable clamp2. Choke cable clmap3. Throttle control lever4. Slot5. Cap screws6. Control plate

Fig. JD7-15–View of fuelshutoff used on Model 455.

A. LocknutB. LinkC. Cable linkD. Pump shutoff leverE. Rod endF. Solenoid plunger

the fast idle stop, pull the throttle cabletight and tighten the cable clamp. Movethe throttle lever through the full rangeand make sure the governor control le-ver moves fully to the slow and fast idlepositions.

Fuel Shutoff Solenoid(Model 455)

The fuel shutoff solenoid holds thefuel injection pump linkage in a closed

position until the battery voltage ener-gizes the solenoid. The solenoid thenmoves the pump linkage so the fuelpump delivers fuel to the engine. Alsorefer to the ELECTRICAL SYSTEMsection.

Adjustment

The shutoff solenoid must be ad-justed so the plunger retracts fullywhile also providing full rack travel onthe fuel injection pump.

To adjust, loosen the locknut (A—Fig.JD7-15) and detach the link (B) fromthe rod end (E). Push the solenoidplunger (F) in until bottomed. Push theinjection pump shutoff lever (D) as faras possible toward the solenoid. Rotatethe rod end (E) so it aligns with the holein link (B), then turn the rod end (E)two turns counterclockwise. Reattachthe link to the rod end. Check for freemovement. Linkage must return to thestop position when the key switch is ro-tated to the OFF position.

Fuel Transfer Pump(Model 455)

The fuel transfer pump is located inthe fuel tank. To test the pump for thecorrect operation, connect a suitablepressure gauge to the fuel tank outputfitting. Turn the ignition switch on, butdon’t start the engine. The minimumallowable fuel pump pressure is 172kPa (25 psi) at a fuel temperature of59-77°F (15-25°C).

Direct a hose from the fuel line into acontainer. The fuel pump volumeshould be at least 450 mL (15 oz.) dur-ing 15 seconds of operation.

Carburetor(Model 425)

Model 425 is equipped with a floatcarburetor.

The initial setting of the idle mixturescrew (1—Fig. JD7-16) is 13

8 turns outfrom a lightly seated position. Start andrun the engine until the normal operat-ing temperature is reached. Turn theidle mixture screw to obtain the highestidle speed (lean mixture), then turn thescrew out counterclockwise an addi-tional 1

4 turn. Adjust the idle stop screw(2) so the engine idles at 1450 rpm. Re-check the throttle cable adjustment.

A fixed jet controls the main fuel mix-ture. The main jet is not adjustable, butdifferent size main jets are available forhigh altitude operation.

The carburetor uses a vent solenoid(4—Fig. JD7-11) in conjunction with anignition delay module to prevent back-fire when the ignition switch is turnedoff. The vent solenoid equalizes thepressure on the upper and lower sidesof the carburetor venturi whende-energized. With the pressure equal-ized, no vacuum is present at theventuri to draw fuel out of the mainnozzle, and fuel flow to the engine isstopped immediately.

Fuel Injection(Model 445)

Model 445 is equipped with an elec-tronically controlled, throttle body fuelinjection system. Fuel mixture settingsare not adjustable.

Slow idle speed is adjusted by turn-ing the slow idle stop screw (S—Fig.JD7-17) while holding the throttle lever(T) in the slow speed position. The slowidle speed should be 1350-1550 rpm.

To adjust maximum unloaded enginespeed (fast idle), run the engine withthe throttle control lever in the maxi-mum speed position. Using an accuratetachometer, check the engine rpm. En-gine speed should be 3450-3650 rpm.Loosen the throttle control plate retain-ing screws (5—Fig. JD7-14) and movethe control plate (6) to adjust the fastidle speed. Retighten screws.

Refer to the REPAIRS section for fuelinjection service information.

Governor(Models 425 and 445)

To adjust the governor linkage,loosen the governor lever clamp nut(N—Fig. JD7-18). Pull the governor le-

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Fig. JD7-16–View showinglocation of idle mixturescrew (1), idle speed stopscrew (2) and throttle lever(3) on Model 425 carburetor.

Fig. JD7-17–To adjust idlespeed on Model 445, holdthrottle lever (T) against idlespeed screw (S) and turnscrew to obtain desiredspeed. Idle speed should beapproximately 1450 rpm.

Fig. JD7-18–To adjust governor linkage onModels 425 and 445, loosen governor leverclamp (N). Pull governor lever (L) counter-clockwise as far as possible and hold lever.Rotate governor shaft (S) as far as possiblecounterclockwise.

ver (L) counterclockwise as far as possi-ble and hold the lever. Insert a smalldiameter rod (R) though the hole in thegovernor shaft (S) and rotate the gover-nor shaft as far as possible counter-clockwise. Retighten nut.

Ignition System(Models 425 and 445)

A breakerless, solid-state ignitionsystem is used. Ignition timing is notadjustable. If a malfunction is sus-pected, refer to the REPAIRS sectionfor the service procedure.

Valve Adjustment

Models 425 and 445

The engine must be cold when check-ing the valve stem end clearance. Re-move the rocker arm cover and unscrewthe spark plugs. Rotate the crankshaftso the piston for the cylinder beingchecked is at top dead center on thecompression stroke. Both the intakeand exhaust valves should be seatedand the rocker arms loose. If not, thepiston is not on the compression strokeand the crankshaft must be turned onecomplete revolution. Piston is at TDCwhen “1" or ”2" mark with the triangleon the flywheel is aligned with the em-bossed triangle on the top side of thecrankcase.

Use a feeler gauge to measure theclearance (A—Fig. JD7-19) betweenthe valve stem and rocker arm. Thespecified clearance is 0.25 mm (0.010in.). To adjust, loosen the jam nut (B)and turn the adjusting screw (C) to ob-tain the desired clearance. Tighten thejam nut to 9 N·m (79 in.-lb.) and re-check the clearance. Tighten spark plugto 25 N·m (221 in.-lb.).

Model 455

Adjust the valve clearance with theengine cold. The specified clearance is0.2 mm (0.008 in.) for both the intakeand exhaust valves.

To adjust the valves, remove therocker arm cover. The number 1 cylin-der is at the flywheel end of the engine.Turn the crankshaft in the normal di-rection of rotation (clockwise facing theflywheel) so the number 1 piston is attop dead center on the compressionstroke. Adjust the intake and exhaustvalves on the number 1 cylinder. Adjustthe valve clearance (A—Fig. JD7-19) byloosening the locknut (B) and turningthe adjusting screw (C) at the push rodend of the rocker arm until a 0.2 mm(0.008 in.) thick feeler gauge is a tightslip fit between the end of valve stemand rocker arm pad.

Continue to turn the crankshaft untilthe next piston in the firing order(1-3-2) is at top dead center on the com-pression stroke and adjust the valvesfor that cylinder in the same manner.Repeat the procedure for each cylinderin order.

Oil Pressure

To check oil pressure, remove the oilpressure sender and connect a suitablegauge to the port. On Model 455, re-move the fuel filter to gain access to theoil pressure sender.

Run the engine until the normal op-erating temperature is reached, thenrecord the oil pressure reading. Theminimum allowable oil pressure withthe engine running at fast idle is 276kPa (40 psi) for Models 425 and 445.The specified oil pressure for Model 455is 294-440 kPa (43-64 psi).

If the oil pressure is below specifica-tion, stop the engine and determine thecause.

Compression Pressure

When checking compression pres-sure, make sure the battery is fullycharged. Minimum cranking speed is250 rpm.

For Models 425 and 445, the mini-mum allowable compression pressureis 1171 kPa (170 psi). Maximum allow-able difference between cylinders is 97kPa (14 psi).

For Model 455, the minimum allow-able compression pressure is 2448 kPa(355 psi). Maximum allowable differ-ence between cylinders is 490 kPa (71psi).

ENGINE REMOVALAND INSTALLATION

Models 425 and 445

Disconnect the negative battery ca-ble. Disconnect the tube to the air re-striction indicator. Remove the frontgrille panel. Unscrew the fasteners se-curing the muffler shield to the front

support. The front support is secured tothe frame by carriage bolts on bothsides. Remove the upper carriage bolton each side, then loosen the lower car-riage bolts and tilt the front supportforward. Unscrew and remove the muf-fler with the shield. Reinstall the en-gine lift bracket after removing themuffler. Disconnect the drive shaftfrom the engine pulley. Drain the cool-ant and disconnect radiator hoses. Dis-connect the choke and throttle cablesfrom the engine.

NOTE: On Model 445, turn thefuel pressure relief screw(C—Fig. JD7-20) one-half turncounterclockwise to relieve thefuel pressure in the fuel injectionsystem before disconnectingfuel lines or hoses.

Disconnect all cables, wires andhoses that will interfere with engine re-moval. Unscrew the engine mountingbolts (D). Attach a suitable hoist to theengine lifting bracket. Carefully lift outthe engine toward the front of the trac-tor to prevent damage to the radiator.

Reverse the removal procedure to in-stall the engine. Be sure there is suffi-cient slack in the ground cable afterattachment. Refer to the COOLINGSYSTEM when refilling the cooling sys-tem. Bleed air from the fuel system aspreviously outlined in the FUEL FIL-TER section.

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Fig. JD7-19–Loosen jam nut (B) and turnadjusting screw (C) to obtain desired clear-ance (A) between valve stem and rockerarm. Refer to text.

Fig. JD7-20–On Model 445, turn fuel pres-sure relief screw (C) one-half turn counter-clockwise to relieve fuel pressure beforedisconnecting fuel lines.

A. Fuel supply hoseB. Throttle control cableC. Fuel system relief

screw

D. Engine mountingbolts

E. Ground cable

Model 455

Disconnect the negative battery ca-ble. Remove the air cleaner assembly.Remove the front grille panel. The frontsupport is secured to the frame by car-riage bolts on both sides. Remove theupper carriage bolt on each side.Loosen the lower carriage bolts and tiltthe front support forward. Remove themuffler assembly.

Disconnect the drive shaft from theengine pulley. Drain the coolant anddisconnect the radiator hoses. Removethe coolant reservoir and the fanshroud. Disconnect all cables, wiresand hoses that will interfere with en-gine removal. Identify wiring as it isdisconnected so it can be correctly re-connected. Plug all fuel hoses to pre-vent dirt from entering the fuel system.

Reposition the lift eye on the leftfront side of the engine so the loop is upfor lifting. Attach a suitable hoist to theengine lift brackets. Unscrew the en-gine mounting bolts. Carefully lift out

the engine toward the front of the trac-tor to prevent damage to the radiator.

Reverse the removal procedure to in-stall the engine. Be sure there is suffi-cient slack in the ground cable afterattachment.

REPAIRS

The following engine repair sectioncovers Models 425 and 445. For Model455, refer to the YANMAR section inthe ENGINE REPAIR section of thismanual for repair procedures.

Tightening Torque

The recommended special tighteningtorque specifications are as follows:

Carburetor . . . . . . . . . . . . . . . . . . . . . 17 N·m(12 in.-lb.)

Connecting rod . . . . . . . . . . . . . . . . . 21 N·m(186 in.-lb.)

Crankcase cover. . . . . . . . . . . . . . . . 21 N·m(186 in.-lb.)

Cylinder head . . . . . . . . . . . . . . . . . . 21 N·m(186 in.-lb.)

Flywheel. . . . . . . . . . . . . . . . . . . . . . 110 N·m(80 ft.-lb.)

Intake manifold . . . . . . . . . . . . . . . . . . 6 N·m(52 in.-lb.)

Muffler . . . . . . . . . . . . . . . . . . . . . . . . . 7 N·m(62 in.-lb.)

Rocker arm nut . . . . . . . . . . . . . . . . . . 9 N·m(79 in.-lb.)

Spark plug . . . . . . . . . . . . . . . . . . . . . 20 N·m(180 in.-lb.)

IGNITION SYSTEM

The ignition system consists of an ig-nition module, two pulser coils (Model445 uses one pulser coil) and two igni-tion coils. On Model 445, the ignitionmodule is a part of the fuel injectionmodule. The 12-volt battery suppliescurrent to the ignition system. A safetyswitch operated by weight on the trac-tor seat disconnects current to the igni-tion system if the operator leaves theseat while the engine is running.

Refer to wiring diagrams at the endof this section for the ignition systemcomponents. Before testing the ignitionsystem, be sure the safety circuit com-ponents are functioning correctly andnot affecting the performance of the ig-nition system.

To check the pulser coil, turn the keyswitch OFF and disconnect the 4-pinpulser coil connector (Fig. JD7-21).Measure the resistance between thewhite/blue wire (A) and pink wire (B),then between the green/white wire (C)and yellow wire (D) at the pulser side ofthe connector. Resistance should be85-270 ohms on Model 425 and 190-290ohms on Model 445.

To test the ignition coil, disconnectthe spark plug cable, positive wire(wide terminal) and negative wire (nar-row terminal). To check the primarycoil resistance, connect the ohmmetertest leads between the positive and neg-ative wire terminals. The primary coilresistance should be 3.4-4.6 ohms. Tomeasure the secondary coil resistance,remove the spark plug cap from thespark plug wire. Connect the ohmmeterleads to the spark plug wire and posi-tive terminal. Secondary coil resistanceshould be 10.4k-15.5k ohms. Measureresistance between the spark plug wireand coil core. Reading should be infin-ity. If readings vary significantly fromthe specifications, replace the ignitioncoil.

Satisfactory tests are not available tocheck the ignition module other thanreplacing the ignition module with agood unit and checking performance.

CARBURETOR(Model 425)

Model 425 is equipped with the floatcarburetor shown in Fig. JD7-22. The

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Fig. JD7-21–Disconnect 4-pinpulser connector to test pulsercoil windings. Refer to text.

Fig. JD7-22–Exploded view ofcarburetor used on Model 425.

1. Air jet2. Gasket3. Choke plate4. Air jet5. Choke shaft6. Seal7. Bushing8. Air horn9.

10. Fuel inlet vlave11. Spring12. Pin13. Float14. Gasket15. Pilot jet16. Seal17. Retainer18. Throttle shaft19. Throttle plate20. Idle speed screw21. Idle mixture screw22. Drain screw23. Main jet24. Body

initial setting of the idle mixture screw(21) is 13

8 turns out from lightly seated.Main fuel mixture is controlled by afixed jet (23). Different size main jetsare available for high altitude opera-tion.

To disassemble carburetor, removeattaching screws and separate the airhorn (8—Fig. JD7-22) from the carbu-retor body (24). Remove the float (13)and fuel inlet valve assembly (9, 10 and11). Remove idle jet (15), idle mixturescrew (21) and main jet (23). It is notnecessary to remove the choke or throt-tle shafts unless wear or damage is evi-dent.

Clean carburetor parts (except plas-tic components) using carburetorcleaner. Do not clean jets or passageswith drill bits or wire as enlargement ofpassages could affect the carburetor’scalibration. Rinse parts in warm waterto neutralize the carburetor cleaner’scorrosive action and dry with com-pressed air.

When assembling the carburetor,note the following. Install choke plate(2) with metering hole toward the fuelinlet side of the carburetor. To check thefloat level, invert air horn and positionfloat so tab (T—Fig. JD7-23) just con-tacts the fuel inlet valve pin. Don’t al-low the float to compress the spring infuel inlet valve. The float should be par-allel with the air horn when inverted asshown in Fig. JD7-23. Bend tab (T) toadjust float position.

FUEL INJECTION SYSTEM(Model 445)

The engine is equipped with a throt-tle body fuel injection system. Refer toFig. JD7-24 for a diagram indicatingthe location of the fuel injection compo-nents. Refer to Fig. JD7-25 for the fuelinjection electrical circuit wiring dia-gram.

Operation

The fuel injection system is an elec-tronically controlled, throttle body sys-tem. The system is divided into twosubsystems, fuel delivery and control.

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FloatT

Needle

Fig. JD7-23–Float should be parallel withair horn surface. Adjust float level by bend-ing float tab (T).

Fig. JD7-24–Drawing showing fuel system components on Model 445.

1. Tank relief/check valve2. Fuel tank cap3. Fuel gauge sensor4. Fuel pump5. Screen6. Fuel filter7. Fuel return hose8. Fuel delivery hose

9. Throttle control plate10. Throttle control lever11. Governor lever12. Fuel pressure relief screw13. Fuel injector14. Fuel return hose15. Fuel pressure regulator

16. Throttle body17. Air restriction indicator18. Sensor19. Throttle cable20. Slow idle stop screw21. Secondary filter element22. Primary filter element

Fig. JD7-25–Wiring schematic for Model 445 fuel circuit.

The fuel delivery system consists ofthe fuel pump (4—Fig. JD7-24)mounted inside the fuel tank, fuel filter(6), fuel injector (13) and pressure regu-lator (15). The fuel pump forces fuelfrom the fuel tank through the filter tothe fuel injector. The fuel injector is lo-cated in the throttle body, which is at-tached to the intake manifold. Excessfuel is routed from the injector to thepressure regulator, which maintainssystem pressure. See the FUEL PRES-SURE REGULATOR section. Leak-offfuel from the regulator is directed backto the fuel tank.

A relief/check valve (1) opens to allowair to enter the fuel tank to prevent avacuum, but closes to prevent gasfumes from escaping into the atmo-sphere. The relief valve opens and al-lows air to escape from the tank if tankpressure exceeds 3 kPa (0.4 psi). Thefuel tank cap is not vented.

The control system consists of thefuel injection control module, fuel injec-tion relay, fuel pump relay and severalsensors. The sensors provide the con-trol module with voltage readings re-lated to air pressure, coolanttemperature and air temperature. Thecontrol module also senses enginespeed through pulses from the ignitionpulser coil.

The fuel injection relay directs cur-rent to the control module when the ig-nition key switch is ON. The controlmodule energizes the fuel pump relaywhen output from the fuel pump is re-quired. The control module controls thetime and duration of fuel injector out-put. Activation of the injector by thecontrol module is determined by inputfrom sensors and related circuits. Note

the two fusible links are located in thesystem to protect system components.

Troubleshooting

If the fuel injection module recog-nizes a problem during operation, anLED on the instrument panel will flasha trouble code identifying the malfunc-tioning circuit. Note that the troublecodes only identify problem areas, notspecific components. A problem may liewith a sensor, faulty wiring, bad con-nection or internal module circuit. Themodule only identifies problems tiedelectrically to the ECU. Other prob-lems, such as fuel delivery problems,will not trigger a trouble code. Troublecodes and related problem areas are:

Long, short, short Air temperaturesensor circuit

Long, short, Coolant sensorshort, short circuitLong, long, short Air pressure sensor

circuitLong, long, short, short Air pressure

sensor circuit*Short, long continuously Multiple sensor

malfunction*Turning key switch to start position beforelight is off will also trigger this code.

Refer to fuel system wiring diagramshown in Fig. JD7-25, and use normaltroubleshooting techniques to isolatethe faulty component. Voltage readingsspecified in the following paragraphsare taken with connectors connected.Be sure the battery is fully charged andall ground connections are good.

The following fuel system circuitsmay prevent the engine from starting ifa malfunction occurs (including starterand ignition circuits):

• Fuel injection module.• Fuel pump circuit.• Fuel injector circuit.• Engine speed circuit.• Starter sensing circuit.A rough running engine may be

caused by a malfunction in the follow-ing:

• Air temperature sensor circuit.• Air pressure sensor circuit.• Coolant temperature sensor circuit.• Engine speed circuit.Note the following when performing

voltage checks:The fuel injection module must pro-

vide 5 V to sensors for the proper opera-tion. Less voltage may be due to a faultymodule.

FUEL PUMP CIRCUIT: When theignition key switch is turned to theRUN position there should be 0.1-0.2 Vfor 2 seconds at thhe fuel injection mod-ule terminal 12 (Fig. JD7-25). Replacethe module if voltage exceeds 0.2 V.With the key held in the start position,there should be 0.1-0.2 V at the fuel in-jection module terminal 12. Replace themodule if voltage exceeds 0.2 V.

With the transmission in NEUTRAL,the PTO switch off, the park brake en-gaged, the seat switch depressed andthe key switch in the RUN position,battery voltage should be read at thefollowing locations: Fuel pump for twoseconds, brake switch, seat switch,PTO switch, fuel injection module ter-minal 10, fuel pump relay terminals 85and 87, safety relay terminal 86, andfuel injection relay terminals 30, 85 and87.

THROTTLE BODY. An explodedview of the throttle body and associatedcomponents is shown in Fig. JD7-26.Note the following when servicing thethrottle body. Loosen fuel pressure re-lief plug (13) before removing any fuellines or components. To remove the in-jector (2—Fig. JD7-26), remove thecover (1) and unplug wire connector.Twist and pull the injector from thethrottle body (3). It is not necessary toremove the throttle shaft (7) unless ex-cessive wear is evident. If throttle shaftbore in throttle body is worn, throttlebody must be replaced.

If removed, install the throttle shaftseal (6) with the lip out. If the throttleshaft was removed, apply a suitablethread-locking compound to the throt-tle plate screws when installing. Thethrottle plate (8) plate must be centeredin the throttle body bore when closedand it must move freely when shaft re-tainer (5) screw is tightened. Tightenthe pressure relief plug (13) to 15 N·m(133 in.-lb.).

FUEL INJECTION MODULE. Ig-nition module is a part of the fuel injec-

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Fig. JD7-26–Exploded viewof throttle body used onModel 445.

1. Retainer2. Fuel injector3. Throttle body4. Gasket5. Retainer6. Seal7. Throttle shaft8. Throttle plate9. Idle speed screw

10. Fuel pressureregulator

11. O-ring12. O-ring13. Fuel pressure

relief plug14. Intake manifold

tion module. Satisfactory tests are notavailable to check the fuel injectionmodule other than replacing modulewith a good unit and checking perfor-mance.

AIR PRESSURE SENSOR. Thesensor monitors air pressure in thethrottle body and adjusts voltage out-put to fuel injection module. Disconnectthe connector to the sensor, then look-ing at the sensor with the air tubepointing down, measure the resistancebetween all connectors. Refer to the fol-lowing:

Left to center terminal . . . 2986-3034 ohmsRight to center terminal . . 3774-3798 ohmsLeft to right terminal. . . . . . . 773-787 ohms

Reconnect the sensor wire connector.Disconnect the air hose from the throt-tle body. Connect the voltmeter positivelead to the red/blue wire and negativevoltmeter lead to black wire. With thekey switch in the ON position, the volt-meter should read approximately 5 V.Connect the voltmeter positive lead tothe white/brown wire. The voltmetershould read less than less than 5 V. Ap-ply a slight vacuum to the air hose andthe voltage should decrease.

AIR TEMPERATURE SENSOR.The air temperature sensor is locatedin the base of the air cleaner. To test thesensor, the key switch must be in theOFF position. Detach the air tempera-ture sensor connector. The resistancereading between the sensor connectorterminals at 68° F (20° C) should be2.21k-2.69k ohms. At a temperaturerange of 32-86° F (0-30° C) resistancereadings should be in range of5.88k-1.65k ohms. Resistance shoulddecrease as temperature increases.

COOLANT TEMPERATURESENSOR. The specified temperaturesand resistance readings are the sameas for air temperature sensor.

FUEL INJECTOR. To test the injec-tor, detach the injector wire connector.The resistance between the injectorpins should be 13.8 ohms at a tempera-ture of 68° F (20° C). Apply negativebattery voltage to one injector pin andtap a wire from the positive battery ter-minal to the other injector pin. The in-jector should “click” each time aconnection is made. If not, replace theinjector.

FUEL PRESSURE REGULATOR(Model 445)

A vacuum-controlled fuel pressureregulator (10—Fig. JD7-26) is locatedon the throttle body of fuel injected en-gines. The regulator varies the fuelpressure according to the air pressurein the intake manifold. A vacuum hoseconnects the regulator to the intake

manifold. This allows the air pressurein the regulator spring chamber and in-take manifold to be equal. When themanifold pressure decreases, the fuelpressure is increased, and vice versawhen the manifold pressure increases.The fuel pressure regulator must beserviced as a unit assembly.

FUEL PUMP(Model 445)

The fuel pump is located in the fueltank. The fuel injection module actu-ates the electric fuel pump electroni-cally. The fuel pressure regulator(10—Fig. JD7-26) controls the fuelpressure.

Testing

This test checks the fuel pressure,which indicates the condition of the fuelpump, fuel pressure regulator, fuel fil-ters and hoses. Before testing the fuelpressure be sure the fuel filter and fuelline are in good condition and the fuelflow to the pump is unimpeded.

NOTE: Turn the fuel pressure re-lief screw (13—Fig. JD7-26)counterclockwise one-half turnand loosen the fuel tank cap torelieve the fuel system pressurebefore disconnecting the fuellines.

Disconnect the fuel return hose(A—Fig. JD7-27) from the throttle bodyfitting (F) and plug the hose. Connect asuitable pressure gauge (B) to the re-turn fitting. Loosen fuel pressure relief

screw one-half turn. Turn ignitionswitch on, but don’t start the engine,and observe the pressure gauge read-ing. Note the fuel pump will only oper-ate for 2 seconds. The minimumallowable fuel pump pressure is172-186 kPa (25-27 psi). Close the fuelpressure relief screw, and reconnect thefuel return hose.

If the fuel pressure is low, check thefuel pump screen (5—Fig. JD7-24), fuelfilter (6) and hoses for restrictions. If noproblem is found, replace the fuel pres-sure regulator or fuel pump.

If the fuel pressure is above specifica-tions, check the fuel tank return line forrestrictions and check fuel pressureregulator vacuum hose for leaks. If noproblem is found, replace the pressureregulator.

CYLINDER HEAD

To remove the cylinder head, firstdrain the cooling system. Remove theair cleaner assembly, carburetor orthrottle body assembly, intake manifoldand muffler.

NOTE: Loosen intake manifoldbolts and cylinder head bolts 1

4

turn at a time in the sequenceshown in Fig. JD7-28 and Fig.JD7-29 to prevent distortion ofthe manifold or cylinder head.

Rotate crankshaft so the piston is attop dead center on the compressionstroke. Remove the rocker arm cover

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Fig. JD7-27–Connect pressure gauge (B) tofuel return fitting (F) to check fuel pumppressure. Refer to text.

Fig. JD7-28–Loosen and tighten intakemanifold bolts in sequence shown to helpavoid distortion of manifold.

Special bolt

Fig. JD7-29–Loosen and tighten cylinderhead bolts in sequence shown to helpavoid distorting the cylinder head. Note lo-cation of special cylinder head bolt.

(2—Fig. JD7-30) Unscrew the cylinderhead screws and remove the cylinderhead.

Mark the position of all valve traincomponents so they can be installed intheir original position. Detach the snaprings (10—Fig. JD7-30) on the rockershaft, withdraw the rocker shaft (11)and remove the rocker arms (12). Com-press the valve springs (5) and disen-gage the spring retainers (4) from thevalve stems. Remove the valve springs,

spring seats (6), seals (7) and valvesfrom the cylinder head. Identify allparts during disassembly so they can bereturned to their original positions. In-stall new valve seals (7) when reassem-bling.

Remove the cylinder head gasket andthoroughly clean the cylinder head sur-face and combustion chamber. Be care-ful not to scratch or damage thecylinder head. Inspect the head fordamage. Check the head for distortion

using a straightedge and feeler gauge.Repair or replace the cylinder head if a0.05 mm (0.002 in.) feeler gauge can beinserted between the straightedge andgasket surface of the head.

Install the cylinder head using a newhead gasket. The new head gasket istreated with a sealing compound andshould be installed dry. No additionalsealant should be applied. Note the po-sition of the special bolt in Fig. JD7-29.Follow the sequence shown in Fig.JD7-29 when tightening the cylinderhead screws. Tighten the screws insteps of 3 N·m (27 in.-lb.) until a finaltorque of 21 N·m (186 in.-lb.) is at-tained. Follow the sequence shown inFig. JD7-28 when tightening the intakemanifold bolts. Tighten the intakemanifold screws in steps of 3 N·m (27in.-lb.) until a final torque of 6 N·m (52in.-lb.) is attained.

Valve System

The valves (14 and 15—Fig. JD7-30)are located in the cylinder head. Cleancarbon from the valve face and stem.Inspect valves for damage and replacewhen necessary.

Valve seats and guides are not re-placeable. Valve face and seat anglesshould be 45º. The valve seat widthshould be 0.80 mm (0.031 in.). The min-imum valve margin is 0.60 mm (0.024in.).

Minimum valve stem diameter is5.94 mm (0.234 in.) for intake and 5.92mm (0.233 in.) for exhaust. Maximumallowable valve guide inside diameteris 6.05 mm (0.238 in.). Maximum valvestem runout measured with valve sup-ported at ends is 0.03 mm (0.001 in.).

Maximum push rod runout measuredwith the push rod supported at the endsis 0.30 mm (0.012 in.). Minimumrocker shaft diameter is 11.95 mm(0.470 in.). Maximum rocker arm innerdiameter is 12.07 mm (0.475 in.).

Inspect the valve springs for damageor evidence of overheating and replacewhen necessary. Minimum valve springfree length is 29.70 mm (1.170 in.).

Piston, Pin, Rings and Rod

Drain the engine coolant, and removethe cylinder heads (8—Fig. JD7-31) aspreviously described. Drain the engineoil. Remove the crankshaft pulley, wa-ter pump and crankcase cover (3) for ac-cess to the piston and rod assemblies.Mark the connecting rods and caps (15)so they can be installed in their originalposition. Remove carbon or ridge fromthe top of the cylinder before removingthe piston to prevent damage to thering lands. Unscrew the connecting rodcap screws, detach the rod cap and re-

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Fig. JD7-30–Exploded view of cylinder head and valve system components for Model 425and 445.

1. Spacer2. Rocker cover3. Gasket4. Valve spring retainer5. Valve spring6. Valve spring seat

7. Seal8. Nut9. Adjusting screw

10. Snap ring11. Rocker shaft12. Rocker arms

13. Cylinder head14. Exhaust valve15. Intake valve16. Dowel pin17. Head gasket

Fig. JD7-31–Exploded viewof crankshaft, piston and rodassemblies used on Models425 and 445.

1. Oil drain valve2. Oil seal3. Crankcase cover4. Cylinder block5. Breather6. Head gasket7. Rocker cover8. Cylinder head9. Oil seal

10. Main bearing11. Snap ring12. Piston pin13. Piston rings14. Piston15. Connecting rod

& cap16. Crankshaft17. Pin18. Crankshaft gear

move piston and rod assembly throughthe top of the cylinder bore.

Clean deposits from the top of the pis-ton and piston ring grooves. Be sure theoil return passages in the ring grooveare open. Inspect the piston for damageand replace when necessary.

Specified piston clearance in cylinderbore is 0.030-0.170 mm (0.0012-0.0067in.). The standard piston diameter is75.935-75.950 mm (2.9896-2.9902 in.).Measure the piston diameter 11 mm(0.43 in.) from the bottom of the pistonperpendicular to the piston pin. Maxi-mum allowable pin bore in piston is17.04 mm (0.671 in.). Minimum allow-able piston pin diameter is 16.98 mm(0.668 in.).

Install each piston ring squarely inthe cylinder bore and measure ring endgap with a feeler gauge. Maximum al-lowable piston ring end gap is 1.20 mm(0.050 in.). If the end gap is excessive,check cylinder for wear.

Insert new compression rings in thering grooves and measure the sideclearance between the ring and ringland with a feeler gauge. Maximum al-lowable piston ring side clearance is0.14 mm (0.006 in.) for top compressionring and 0.12 mm (0.005 in.) for the sec-ond compression ring. Pistons andrings are available in standard size and0.5 mm (0.020 in.) oversize. Refer to theCYLINDER BLOCK section if oversizepistons are required.

The connecting rod rides directly onthe crankpin. Maximum allowable in-side diameter at big end of rod is 34.06mm (1.341 in.). Minimum allowablecrankpin journal diameter is 33.93 mm(1.336 in.). Maximum allowable insidediameter at pin end of rod is 17.05 mm(0.671 in.). The connecting rod is avail-able with the standard size big end di-ameter as well as with 0.50 mm (0.020in.) undersize big end diameter.

Assemble the piston and connectingrod as follows: On the number one pis-ton and rod assembly, align the arrowmatch mark on the piston crown (Fig.JD7-32) with the “MADE IN JAPAN”marking on the connecting rod. Onnumber two piston and rod assembly,align arrow match mark on pistoncrown opposite the “MADE IN JAPAN”marking on the connecting rod.

NOTE: Do not reuse piston pinretainers (11—Fig. JD7-31). In-stall new retainers if removedfrom the piston.

Install piston rings with the letteredside towards the piston crown. See Fig.JD7-33. Position piston rings so ringgaps are 180º apart. Lubricate the pis-

ton and rings with engine oil prior toinstalling in the cylinder bore.

Install piston and rod assemblies oncrankshaft so the arrow mark on bothpistons is pointing toward the flywheelas shown in Fig. JD7-32. Note the“MADE IN JAPAN” side of the connect-ing rods should be facing away fromeach other and the large chamfer side ofeach rod big end is next to the crank-shaft web. Make sure the rod capmatches the connecting rod. Tightenrod cap screws to 21 N·m (186 in.-lb.).Tighten crankcase cover screws to 21N·m (186 in.-lb.) in the sequence shownin Fig. JD7-34. Install cylinder head aspreviously outlined.

Camshaft

The camshaft is accessible after re-moving the crankcase cover. Rotate thecrankshaft to align the timing marks(M—Fig. JD7-35) on camshaft andcrankshaft gears prior to removing thecamshaft.

The camshaft rides innonreplaceable bushings in the cylin-der block and crankcase cover. Replace

the cylinder block or cover if the bush-ing diameter is greater than 16.07 mm(0.633 in.).

Minimum allowable camshaft bear-ing journal diameter is 15.91 mm(0.626 in.). Minimum allowable cam-shaft lobe height is 25.21 mm (0.992 in.)for intake lobe and 25.46 mm (1.002 in.)for exhaust lobe. Minimum fuel pumplobe height is 19.50 mm (0.768 in.).

When installing camshaft, be sure toalign the timing marks (M—Fig.JD7-35) on the camshaft and crank-shaft gears. Tighten the crankcasecover screws to 21 N·m (186 in.-lb.) inthe sequence shown in Fig. JD7-34.Note the cap screw located at top centerof the water pump attaches the crank-case cover to the crankcase and shouldbe tightened to 21 N·m (186 in.-lb.). Theremainder of the water pump mountingscrews should be tightened to 8 N·m (70in.-lb.).

Crankshaft and Main Bearings

To remove the crankshaft, first drainthe coolant and engine oil. Remove the

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Raised letters(Made in Japan)

Flywheelside

Match marks

Raised letters(Made in Japan)

Fig. JD7-32–On Models 425 and 445, notethe location of arrow marks on top of pis-tons in relation to “MADE IN JAPAN” onconnecting rods. No. 1 piston is oppositethat of No. 2 piston. Refer to text.

Firstcompression

ring

Secondcompression

ring

Side rails

Spacer

Fig. JD7-33–Cross section of piston andrings showing correct installation onModels 425 and 445. Be sure that “R” or“NPR” mark on end of top ring and secondring faces up. Oil ring can be installed ei-ther way.

Fig. JD7-34–On Models 425 and 445,tighten oil pan screws in sequence shownabove.

Fig. JD7-35–On Models 425 and 445, aligntiming marks (M) on crankshaft and cam-shaft gears when installing camshaft.

engine from the tractor. Remove theflywheel, crankshaft pulley, waterpump and crankcase cover. Rotate thecrankshaft to align the timing markson the camshaft and crankshaft gear,then remove the camshaft. Remove theconnecting rod cap screws and push pis-tons to top of the cylinders. Withdrawthe crankshaft.

The crankshaft rides in a replaceablebushing (10—Fig. JD7-31) in the cylin-der block and a nonreplaceable bushingin the crankcase cover (3). Maximum al-lowable bushing diameter in block is34.11 mm (1.343 in.). Maximum allow-

able bushing diameter in crankcasecover is 34.07 mm (1.341 in.). Minimumallowable crankshaft main bearing jour-nal diameter is 33.91 mm (1.335 in.).

Minimum allowable crankpin diame-ter is 33.93 mm (1.336 in.). Thecrankpin may be reground to accept aconnecting rod with a 0.50 mm under-size big end. Maximum allowablecrankshaft runout is 0.05 mm (0.002in.) measured at the main bearing jour-nals with the crankshaft supported atends.

When installing the crankshaft, besure timing marks (M—Fig. JD7-35) oncrankshaft and camshaft gears arealigned. Tighten the crankcase coverscrews to 21 N·m (186 in.-lb.) in the se-quence shown in Fig. JD7-34. Installnew crankshaft oil seals with the lipfacing inward.

Cylinder Block

The cylinders may be bored to acceptoversize pistons. The standard bore di-ameter is 75.98-76.00 mm (2.994-2.995in.) and the maximum wear limit is 76.07mm (2.997 in.). Be sure to check the borediameter when the cylinder is cold.

After honing the cylinder bore, cleanthe cylinder thoroughly using soap andwarm water. Do not use gasoline, kero-sene or other commercial solvents toclean the cylinder bores. Solvents willnot remove all the abrasives from thecylinder wall.

Governor

A flyweight governor (2—Fig.JD7-36) is located in the crankcase

cover. The governor gear is driven bythe camshaft gear. Remove the crank-case cover for access to the governor as-sembly. The governor componentsmust move freely without binding.

The governor is serviced as an assem-bly. Remove the governor assembly byprying or pulling off the shaft. The shaftmust protrude above the boss 32.2-32.8mm (1.27-1.29 in.). Install the governorby pushing down until it snaps onto thelocating groove. Tighten the crankcasecover screws to 21 N·m (186 in.-lb.) inthe sequence shown in Fig. JD7-34.

To adjust the governor linkage,loosen the clamp bolt (5—Fig. JD7-36)Pull the governor lever (6) counter-clockwise as far as possible and holdthe lever. Rotate the governor arm (4)as far as possible counterclockwise andtighten the clamp bolt.

Oil Pump

A gerotor oil pump (Fig. JD7-37) is lo-cated in the crankcase cover. The pumpprovides pressurized oil that is directedto the crankshaft main bearing journalsand crankpin. Drilled passages in theconnecting rods squirt oil on the under-side of the pistons. A screen preventsforeign matter from entering the pump.

To check oil pressure, remove the oilpressure switch in the side of the cylin-der block adjacent to the oil filter andconnect an oil pressure gauge. With theengine at its operating temperatureand running at the fast throttle setting,the oil pressure should be no less than276 kPa (40 psi).

Remove the crankcase cover for accessto the pump. Note the oil pump cover(7—Fig. JD7-37) holds the relief valveball (1) and spring (2) in place. Removeand clean the oil pick-up screen (10).

Replace the relief valve spring (2) ifthe length is less than 19.50 mm (0.768in.). Maximum inner rotor-to-outer ro-tor clearance is 0.3 mm (0.012 in.). Min-imum allowable rotor shaft diameter is10.92 mm (0.430 in.). Rotors (3 and 4)and rotor shaft (5) are renewed as a kit.Maximum allowable bore diameter inoil pan and pump cover is 11.07 mm(0.436 in.). Maximum rotor bore diame-ter in crankcase cover is 40.80 mm(1.606 in.). Replace the crankcase coverif wear is excessive.

When assembling the oil pump, fillthe rotor housing with engine oil to pro-vide initial lubrication. Be sure the holein the cover (7) is centered over the re-lief valve.

COOLING SYSTEM

Radiator

Radiator cap pressure rating is 90kPa (13 psi).

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Fig. JD7-36–Exploded viewof governor linkage used onModels 425 and 445.

1. Thrust washer2. Governor gear3. Sleeve4. Governor arm5. Clamp bolt6. Governor lever7. Control plate8. Throttle link9. Governor link

& spring

Fig. JD7-37–Exploded view of engine oilpump used on Models 425 and 445.

1. Oil pressurerelief ball

2. Spring3. Outer rotor4. Inner rotor5. Shaft

6. Pins7. Cover8. Oil pump

gear9. Screen retainer

10. Screen

WARNING: The coolant in the ra-diator is pressurized. Removeradiator cap only when the en-gine is cold.

To remove the radiator, drain thecoolant. Disconnect the hydraulic linesto the radiator and drain the hydraulicfluid from the radiator. Disconnect thecoolant hoses. Remove the radiatorscreen and coolant reservoir. Unscrewthe fan shroud and move it out of theway. Disconnect the choke control ca-ble, if so equipped, and throttle controlcable. Remove the radiator mountingfasteners and remove radiator.

Coolant system capacity is approxi-mately 2.8 liters (3.0 qt.). The recom-mended coolant is a 50/50 mixture ofclean water and permanent antifreeze.Antifreeze must be suitable for use inaluminum engines.

Water Pump(Models 425 and 445)

To remove the water pump, firstdrain the coolant. Disconnect the hosesfrom the pump. Unbolt and remove thepump assembly, noting the position andlength of the cap screws.

Refer to Fig. JD7-38 for an explodedview of the water pump. Use a suitablepuller to remove the pump drive gear(13). The impeller (3), shaft (7) and pin(6) are available as a unit assemblyonly. The minimum allowable diameterof shaft is 9.94 mm (0.391 in.). The max-imum allowable diameter of housingbore is 10.09 mm (0.397 in.). Install theseal (4) using the driver provided in theseal kit.

When assembling the pump, coat theimpeller (3) and seal (4) mating sur-faces with clean water to provide lubri-cation. Install the pump. Tighten the 6mm mounting screws to 8 N·m (71in.-lb.) and 8 mm mounting screw to 21N·m (186 in.-lb.).

BRAKES

All models are equipped with a discbrake contained in a compartment onthe transaxle. Brake discs are locatedon the transaxle reduction shaft. Whenthe brake pedal is depressed, brakelinkage also actuates the differentiallock mechanism so the axles are lockedtogether to provide braking to both rearwheels.

ADJUSTMENT

Adjust differential lock linkage as fol-lows: Disconnect the link (5—Fig.JD7-39) from the brake lever (4).Loosen jam nut on the turnbuckle (2).

Pull the lower leg of the brake lever (4)to the front so the brake is engaged. Ro-tate the turnbuckle (3) so the differen-tial lock arm (1) just contacts thedifferential lock shaft. Lengthen theturnbuckle by rotating 21

2 turns, thentighten the jam nut. Connect the link(5) to the brake lever (4). If the brake le-ver has two holes, place the link end inthe higher hole.

Adjust brake linkage as follows:There should be no free play in thebrake linkage with the pedal released.To adjust, disconnect the brake rodclevis (12) from the brake cross shaft.

Rotate the clevis to remove free play inthe linkage, but do not preload thebrakes or excessive wear will result.

OVERHAUL

To gain access to the brake assembly,remove the transaxle as described inthe TRANSAXLE section. An explodedview of the brake assembly is shown inFig. JD7-40.

NOTE: Be prepared to catchloose balls (8) when removingcover (3).

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Fig. JD7-38–Exploded view of water pump used on Models 425 and 445.

1. Cover2. Gasket3. Impeller4. Seal5. O-ring

6. Pin7. Shaft8. Pin9. Seal

10. Housing11. Gasket12. Washer13. Gear

Fig. JD7-39–Drawing of brake linkage. Refer to text for brake adjustment.

1. Differential lock arm2. Turnbuckle3. Link4. Brake arm

5. Brake link6. Park brake rod7. Brake spring8. Brake pedal

9. Return spring10. Park brake rod11. Brake rod12. Turnbuckle

Disconnect the brake linkage (1 or 2).Unscrew the fasteners and remove thebrake cover (3). Remove the actuator(4), brake discs (6) and plates (5). De-tach the snap ring (7) and remove thebrake lever (10) from the cover.

Inspect brake components for dam-age. Replace the brake discs (6) if theradial grooves are worn away.

Reassemble the brake by reversingthe disassembly procedure. Lubricatethe seal (9) before installing the brakelever. Use petroleum jelly to hold theballs (8) in the cover. Apply gas-ket-forming sealer to the mating sur-faces of cover and transaxle. Tightenthe cover screws to 25 N·m (221 in.-lb.)on a used transaxle case or to 30 N·m(22 ft.-lb.) on a new transaxle case.

HYDROSTATIC

TRANSMISSION

MAINTENANCE

Periodically inspect the transmissionfor leakage. Oil for the transmission isrouted from the oil sump in the finaldrive housing. A spin-on filter mountedon the final drive housing protects thehydrostatic transmission and other hy-draulic components.

Refer to the FINAL DRIVE sectionfor the oil change procedure. Change oilfilter after first 50 hours of operationand every 200 hours thereafter.

SYSTEM OPERATION

The charge pump (6—Fig. JD7-41)mounted on the front of the hydrostatictransmission provides pressurized oilfor the transmission, PTO, hydrauliclift and power steering systems. Thehydraulic system uses oil contained inthe final drive housing (1).

Oil from the housing sump passesthrough a filter (3), then to the chargepump. Pressurized oil in the chargepump passes through a flow controlvalve (7) blocking the outlet flow if thepressure falls below 1965 kPa (285 psi).When the flow control valve closes, oilmust flow to the lube reduction valve(12) to insure lubricating oil will flow tothe transmission. The lube reductionvalve maintains the lubrication pres-sure at 586 kPa (85 psi) as well as di-recting oil to the PTO circuit (19). Theimplement relief valve (16) protects thesystem from the pressure exceeding6371-7350 kPa (923-1065 psi).

Outlet oil from the charge pump trav-els to the power steering control valveand hydraulic lift circuits. Also refer tothe POWER STEERING and HY-DRAULIC LIFT sections.

139



Fig. JD7-40–Exploded viewof brake assembly.

1. Interlock linkage2. Link3. Brake cover4. Actuator plate5. Steel plate6. Friction plates7. Snap ring8. Ball (3)9. O-ring

10. Brake cam lever11. Interlock arm

1. Transaxle case2. Inlet from case3. Filter4. To charge pump5. Hydrostatic motor6. Charge pump7. Charge pressure

control valve8. Outlet to steering9. Lube passage.

10. Return from cooler

11. PTO flow orifice12. Lube reduction valve13. Charge pressure

test port14. Center section15. Reverse directional valve16. Implement relief valve17. Forward directional valve18. Passage to solenoid19. PTO pressure

control valve

20. PTO solenoid21. Clutch & brake

pressure testport

22. PTO brake23. Brake spring24. Brake piston25. Brake shoe26. Clutch piston27. Clutch lube

passage

Fig. JD7-41–Drawing of hydrostatic drive showing fluid flow and location of components.

Directional valves (15 and 17—Fig.JD7-41) in the valve block are checkvalves that open to allow pressurizedoil from the charge pump to enter thehydrostatic transmission. Depressingthe freewheeling pins on the directionalvalves unseats the check valves to ventoil pressure, thereby allowing the trac-tor to be pushed when the engine isstopped.

Anti-cavitation valves are located inthe internal fluid passages of the trans-mission. The valves prevent motor cavi-tation by allowing the sump oil into thecircuit when the motor is the driving el-ement, such as when the freewheelingor traveling downhill.

ADJUSTMENTS

Neutral Adjustment

Raise and block up the rear of thetractor so the wheels clear the ground.Start the engine and run at idle speed.With the transmission foot controls re-leased, the rear wheels should not ro-tate.

NOTE: A cutout section of theframe on the tractor’s right sideprovides access to the neutraladjustment screw.

If the wheels rotate, loosen the nut(N—Fig. JD7-42). Start the engine andrun at idle speed. Rotate the eccentricscrew (S) in one direction until thewheels just begin to turn, then rotatescrew in the opposite direction until thewheels just begin to turn again. Positionthe screw at the midpoint, then tightenthe nut (N). Run the engine at idlespeed, and depress and release both theforward and reverse pedals. If thewheels rotate with the pedals released,repeat adjustment.

NOTE: If the eccentric screw (S)will not hold the adjustment, ro-tate the eccentric screw 180º andrepeat adjustment.

If neutral adjustment is not possible,check for a faulty linkage, and if neces-sary, perform the adjustment with thelinkage disconnected.

Control Linkage Adjustment

The transmission control linkageshould be adjusted so the transmissionreturns to NEUTRAL and the controlpedals are locked in NEUTRAL whenthe parking brake is set.

To adjust, first perform the trans-mission neutral adjustment as previ-ously described. Loosen nuts (N—Fig.JD7-43) on the swash plate control rod.

Fully depress the brake pedal. Lookingfrom the inside right frame, measurethe gap (G) between the hook (H) andpin (P). Rotate the control rod (R) sothe gap is 1-2 mm (0.04-0.08 in.).Loosen the nut (T). With the brakepedal fully depressed, adjust the screw(S) so it just contacts the ramp on theneutral return linkage. Retighten thenuts.

Pedal Height Adjustment

The forward pedal height should beadjusted to insure the full travel speedcan be attained. The pedal is threadedonto the top of the control rod. Loosenthe jam nut and rotate the pedal on therod so the pedal contacts the footrestpanel when the control rod reaches thefull down position.

TESTING

Flow Test

Attach a suitable thermometer to thespin-on filter to monitor the oil temper-ature. It may be necessary to block theairflow through the radiator to raisethe oil temperature.

Remove the rear deck and move, butdo not disconnect the fuel lines or fueltank. Disconnect hydraulic lines fromthe charge pump and connect aflowmeter to the charge pump ports.Connect the flowmeter inlet to thecharge pump outlet port (5—Fig.JD7-44) and the flowmeter outlet to thecharge pump inlet (3). Check the oilflow with the engine running at fullthrottle and the oil temperature at 110°F (43° C). Normal oil flow is 17.0 L/m

140



Fig. JD7-42–When adjustingtransmission neutral posi-tion, loosen nut (N) and turneccentric screw (S).

Fig. JD7-43–Refer to text for control linkage adjustment.

G. GapH. HookN. Nuts

P. PinR. Control rod

S. ScrewT. Nut

(4.5 gpm). The minimum allowable oilflow is 13.0 L/m (3.5 gpm).

NOTE: The flow test may be per-formed at the hydraulic couplers(see HYDRAULIC SYSTEM), butthe results will not isolate theproblems.

If the oil flow is nonexistent, checkthe following: the input shaft not turn-ing; the charge pump drive keysheared; the charge pressure controlvalve stuck closed; plugged lube reduc-tion valve modulation orifice.

If the oil flow is below specification,erratic or foamy, check the following:

hydraulic oil level; restricted oil filter;plugged transaxle vent; leaking filterseal; oil ring at charge pump inlet; leak-age between filter and charge pump inhousing; loose dipstick or damagedO-ring; damaged or stuck open imple-ment relief valve; faulty pump.

Pressure Test

Pressure may be tested either using aflowmeter connected as described in aprevious flow test or with a pressuregauge. To check pressure with a pres-sure gauge, unscrew the plug (1—Fig.JD7-44) on top of the transmission andconnect a suitable gauge to the port. Analternate method for checking the sys-

tem pressure is described in theHYDRAULIC SYSTEM section.

Run the engine at full throttle. If us-ing a pressure gauge, move the hydrau-lic lift control lever to the raise or lowerposition so the relief valve operates.Maximum pressure should be6371-7350 kPa (924-1065 psi).

Inadequate pressure may indicate amaladjusted relief valve, faulty chargepump, plugged modulation orifice inthe lube reduction valve, or excessiveleakage in transmission pump.

CHARGE PUMP

Removal and Installation

The charge pump (2—Fig. JD7-44)may be removed without removing thetransmission. Drain oil from the finaldrive housing. Remove the fuel tank.Thoroughly clean the charge pump andsurrounding area to prevent dirt fromentering the hydraulic system. Loosenthe clamp screws at the rear of thedrive shaft (4). Unscrew the retainingscrews at the drive shaft’s front end.Remove the drive shaft. Disconnect hy-draulic lines from the charge pump.

NOTE: When removing thecharge pump, be careful not todrop the pump components asthey are easily damaged.

Unscrew the charge pump retainingscrews and remove the pump from thetransmission.

Install the charge pump by reversingthe removal procedure. Be careful notto damage the oil seal or disturb theO-rings during installation. Tightenthe short lower retaining screws to 25N·m (221 in.-lb.) and the long upper re-taining screw to 39 N·m (29 ft.-lb.).

Overhaul

Refer to Fig. JD7-45 for an explodedcharge pump view. Remove the plug (1)and withdraw the pressure reducingvalve spool (5), spring (4) and shim (3).Remove plug (13), spring (11) andcharge pressure relief valve (10).

Inspect components for damage, in-cluding scratches, burrs and nicks. Re-place the valve block if the block surfaceis scored. Be sure the small orifice in thelube reduction valve spool (5) is open.Lube reduction valve components areavailable only as a unit assembly. Pumprotors (20 and 21) and pump body (14)are available only as a unit assembly.

If the bushing (9) is removed, drivethe bushing into the pump body untilbottomed. Install the seal (8) into thebore with closed side out. Push the sealin until bottomed in the bore. Lubricate

141



Fig. JD7-44–Drawing show-ing location of charge pumpinlet port (3), outlet port (5)and test port (1).

Fig. JD7-45–Exploded view of charge pump.

1. Lube reductionvalve plug

2. Packing3. Shim4. Spring5. Spool6. Plug7. O-ring

8. Seal9. Bushing

10. Poppet valve11. Spring12. O-ring13. Charge pressure

control valve plug14. Pump housing

15. Packing16. Packing17. Packing18. Packing19. Plug20. Outer rotor21. Inner rotor22. Woodruff key

bushing and seal with clean hydraulicoil. Replace all O-rings (15-19).

MOTOR AND VALVE BLOCK

Overhaul

Remove the final drive from the trac-tor as described in a following section.

NOTE: When removing thecharge pump, be careful not todrop pump components.

Unscrew the charge pump retainingscrews and remove the pump from thetransmission. Unscrew the three screwsretaining the valve block, and removethe motor and valve block as a unit fromthe final drive case. Detach the snapring and slide the pinion gear off the out-put shaft. Unscrew the motor retainingscrews and separate motor from thevalve block while being careful not todrop the valve plate (26—Fig. JD7-46).

Valve Block

Remove the directional check valves (1and 3—Fig. JD7-46). The plunger pinand internal valve must move freelywhen the directional valves are shaken.Be sure the orifice (G) in the reversecheck valve is open. Remove the imple-ment relief valve components (12-19) andanticavitation valve assembly (27-34).

Thoroughly clean and inspect allcomponents. Check the suction screen(27) for blockage. Note that the screenmay be located in a bore in thetransaxle housing. Inspect the surfacesof valve block (14) and valve plates (20and 26) for scoring or scratches. Whenscratches can be detected by feel usinga lead pencil or fingernail, the partmust be replaced.

Directional check valves are similarbut not identical. The reverse checkvalve (1) is identified by a small orifice(G) located in a land between the twovalve passageways. The reverse checkvalve must be installed in the left port(marked “R”) on the valve block.

Install needle bearings (21 and 24)with the stamped end out. The bearingmust protrude 3 mm (0.12 in.) abovethe surface of the valve block.

Valve plates (20 and 26) are similarbut not identical. The slotted ports onthe pump valve plate (20) have feather-ing grooves into two ports. Featheringgrooves are absent on motor valveplate. Replace either valve plate if dam-aged. When assembling, use petroleumjelly to hold the valve plate in position.Be sure the bronze surface faces awayfrom the valve block and the locatingpin in valve block engages the notch invalve plate.

Motor

Refer to Fig. JD7-47 when disassem-bling and reassembling the motor com-ponents. Mark the pistons (11) so theycan be reinstalled in their original cyl-inder bores. Use care when removingthe seal cap (24) to prevent damage tothe bearing (22). Remove the snap ring(23) and withdraw the motor shaft (12).

Thoroughly clean and inspect thecomponents. Check the machined sur-face of the cylinder block for scratchesor grooves. The cylinder block must bereplaced if scratches or grooves can bedetected by feel. Check pistons for scor-ing or discoloration indicating over-heating. The pistons must move freelyin the cylinder bores.

NOTE: If any pistons (11) slideout of the cylinder, return themto their original bores.

Motor components (6-11) are avail-able only as an assembly. Bushing (15),thrust washer (16) and housing (19) areavailable only as an assembly.

Reassemble ValveBlock and Motor

When assembling the valve block andmotor, note the following: Thoroughlylubricate components with clean trans-mission oil. Tighten direction checkvalves (1 and 3—Fig. JD7-46) to 35 N·m(26 ft.-lb.). Tighten bottom suction plug(36) to 50 N·m (37 ft.-lb.). Tighten imple-ment relief valve plug (12) to 25 N·m(221 in.-lb.). Install the valve plates (20and 26) on valve block using petroleumjelly to hold each in place. Position platewith bronze face out. The notch in theplate must fit around the pin on thevalve block.

Apply gasket-forming sealer to thecap (24—Fig. JD7-47) and push the capin until it is 4 mm (0.16 in.) below the

142



Fig. JD7-46–Exploded view of hydrostatic transmission valve block.

1. Directional valve(reverse)

2. Nut3. Directional valve

(forward)4. O-ring5. Backup ring6. O-ring7. Packing8. Spool

9. Ball10. Spring11. Seat12. Implement relief

valve plug13. O-ring14. O-ring15. Washer16. Shims17. Washer

18. Spring19. Plunger20. Valve plate21. Bearing22. Dowel pin23. Valve block24. Bearing25. Dowel pin26. Valve plate27. Strainer

28. Anti-cavitationvalve body

29. Backup ring30. O-ring31. Ball32. Seat33. Spring34. Retainer35. O-ring36. Plug

housing surface. Tighten the mo-tor-to-valve block retaining screws to39 N·m (29 ft.-lb.).

PUMP

Overhaul

The transmission pump is containedin a compartment in the final drivehousing and rides on the input shaft.To remove the pump, remove the motorand valve block as described in the pre-vious section. Remove the pump from

the input shaft while being careful notto drop the pistons from the cylinder.

NOTE: If any pistons (4—Fig.JD7-48) slide out of the cylinder,return them to their originalbores.

Refer to the FINAL DRIVE section toremove the swashplate and input shaft.Refer to Fig. JD7-48 when disassem-bling and reassembling pump compo-

nents. Mark pistons so they can be rein-stalled in their original cylinder bores.

Thoroughly clean and inspect compo-nents. Replace the pump assembly ifscratches can be detected by feel on themachined surface of motor block. Pis-tons must move freely in cylinder blockbores.

Pump components (4-9) are availableonly as an assembly.

FINAL DRIVE

AND REAR AXLES

MAINTENANCE

The recommended oil is John DeereLow Viscosity Hy-Gard (J20D) trans-mission oil. Using other oils may causechattering in the PTO or brake units.Oil capacity is 5.6 liter (6 qt.) for2-wheel steering tractors and 6.6 liters(7 qt.) for 4-wheel steering tractors.

DRIVE SHAFTOVERHAUL

To remove the drive shaft, remove thefuel tank. Loosen clamp screws at therear of the drive shaft. Unscrew the re-taining screws at the front end of thedrive shaft. Remove drive shaft.

Inspect for damage. The drive shaftand joint are available only as a unit as-sembly.

Reverse the removal procedure to re-install the drive shaft. Install the frontisolator plate so the bosses are towardthe drive shaft.

REMOVAL AND INSTALLATION

To remove the final drive housingwith axles, drain the transmission oil.Remove the rear fender and fuel tank.Disconnect the hydraulic lines from thecharge pump. Loosen clamp screws atthe rear of the drive shaft. Unscrew theretaining screws at the front end of thedrive shaft. Remove drive shaft.

Remove the rear PTO shield and dis-connect the rear PTO control rod. Dis-connect the interfering electricalconnectors. Remove the rear hitchplate. Disconnect the brake linkage anddifferential lock linkage. On 4-wheelsteering models, disconnect the inter-mediate link connecting the rear steer-ing arm to the rear pivot plate.Disconnect transmission control rod.

Support the rear of the tractor withsuitable stands and remove the rearwheels. Disconnect the lift cylinderfrom the rockshaft. Remove the snaprings and bushings at each end of therockshaft and remove the rockshaft.Support the final drive unit with a suit-able hoist, unscrew the retaining

143



Fig. JD7-47–Exploded view of hydrostatic transmission motor.

1. Snap ring2. Bevel pinion gear3. Bearing4. Valve block5. Snap ring6. Washers7. Spring8. Cylinder block

9. Spring10. Shim11. Piston12. Shaft13. Thrust plate (thick)14. Thrust bearing15. Bushing16. Thrust plate (thin)

17. Gasket18. Dowel pins19. Motor housing20. Snap ring21. Washer22. Bearing23. Snap ring24. Cap

Fig. JD7-48–Exploded view of hydrostatic transmission pump.

1. Swashplate shaft2. Thrust bearing3. Thrust plate (thick)4. Piston

5. Shim6. Spring7. Cylinder block

8. Washers9. Spring

10. Snap ring

screws at the axle housings and removethe unit.

Reinstall by reversing the removalprocedure. Tighten the retainingscrews to 88 N·m (65 ft.-lb.). Refill withtransmission oil.

REAR AXLES OVERHAUL

2-Wheel-Steering Models

Remove the final drive housing andaxles as previously described. Unscrewthe axle housing retaining screws andseparate the axle housing assemblyfrom the final drive housing.

To remove the axle from the axlehousing, detach the snap ring (2—Fig.JD7-49) from the axle housing. Pressthe axle assembly out of the axle hous-ing. Detach the snap ring (8) and re-move the bearings and spacers from theaxle shaft.

To assemble the axle, install thebearing (6), seal (5) and snap ring (A) inthe axle housing. Be sure the seal (5) isinstalled with the open side in. Applypetroleum jelly to the inside diametersof the seal and sleeve (4). Use a piece ofpipe with the inside diameter that willfit over the axle shaft to push thewasher (3) and sleeve (4) against shoul-der on the shaft.

NOTE: Care must be used whenpressing the axle into the hous-ing to prevent damage to thehousing.

Press the axle shaft into the housing.Install washer (7) and snap ring (8) onthe axle shaft, using a piece of pipe topush them into place.

Apply gasket-forming sealer to theaxle housing mating surface. Installthe axle housing and tighten the retain-ing screws to 54 N·m (40 ft.-lb.).

4-Wheel-Steering Models

Remove the final drive housing andaxles as previously described. Unscrewthe steering pivot plate (2—Fig.JD7-50) from the axle housing. Discon-nect the tie rod (3) from the steeringarm (4). Unscrew the axle housing re-taining screws and separate the axlehousing assembly from the final drivehousing.

Detach the steering arm (24—Fig.JD7-51) from the steering knuckle (18).Remove the upper kingpin (17) and sep-arate the knuckle, hub and U-joint as-sembly from the axle. Inspect thebushing (3), bearing (4) and seal (5) fordamage and replace when necessary.

To remove the axle (6) from the hous-ing, remove the seal (10) and snap ring(8). Press the axle with the bearing out

144



Fig. JD7-49–Exploded viewof rear axle assembly usedon 2-wheel-steering trac-tors.

1. Axle2. Snap ring3. Washer4. Sleeve5. Seal6. Bearing7. Washer8. Snap ring9. Axle housing

Fig. JD7-50–Drawing of steer-ing linkage used for rear-wheel steering models

1. Axle housing2. Rear steering

pivot3. Tie rod4. Steering arm

1. Dowel pins2. Axle housing3. Bushing4. Bearing5. Seal6. Axle

7. Bearing8. Snap ring9. Snap ring

10. Seal11. Universal joint12. Seal

13. Bearing14. Washer15. Snap ring16. Grease fitting17. King pin18. Steering knuckle

19. Seal20. Hub21. Washer22. Snap ring23. Cap24. Steering arm

Fig. JD7-51–Exploded view of right rear axle assembly used on 4-wheel steering tractors.Left rear axle assembly is similar

of the housing. Reverse the procedureto install the axle in the housing. In-stall the seal (10) with the open side to-ward the bearing (7).

To disassemble the hub and knuckleassembly, remove the seal cap (23—Fig.JD7-51). Detach the snap ring (22) andremove the universal joint (11). Removethe outer seal (19). Remove the innerseal (12), bearing (13), snap ring (15)and bearing (13).

Thoroughly clean all parts and in-spect for damage.

To assemble, push the bearing (4)into its bore until bottomed. Install theseal (5) with the open side out. Push thebushing (3) into the bore until flushwith the surface. Lubricate the bushingwith multipurpose grease.

When assembling the knuckle andhub, push the outer bearing (13) in un-til bottomed in the knuckle. Fill thebearing cavity with multipurposegrease. Force the spacer (14) and innerbearing (13) against the outer bearing.Install seals (12 and 19) with the openside in. Push the seal (19) in until flushwith the surface. Push the seal (12) inuntil bottomed. Install the wheel hub(20) in the knuckle housing. Applygrease to the splines on the universaljoint shaft, then slide it into theknuckle housing. Install the washer(21), snap ring (22) and seal cap (23).

Apply Loctite to the kingpin (17) andsteering arm (24) retaining screws.Tighten screws to 54 N·m (40 ft.-lb.). In-

ject multipurpose grease into the king-pin fitting until grease appears at theupper joint.

Reverse the removal procedure to in-stall the axle housing. Apply gas-ket-forming sealer to the axle housingmating surface. Note that three loweraxle housing retaining screws are lon-ger than the upper screws. Tighten axlehousing retaining screws to 54 N·m (40ft.-lb.).

FINAL DRIVEOVERHAUL

Remove the final drive and axles aspreviously described. Remove thebrake, axle housings, PTO brake, PTOclutch, PTO gears and hydrostatictransmission as described in relatedsections. Remove the control damper(20—Fig. JD7-52).

Remove the snap ring (17—Fig.JD7-53), then remove the input shaft(14) and bearing (18). Position the finaldrive housing on its left side, then re-move the right cover (10—Fig. JD7-52)assembly. Lift the differential assembly(42-49—Fig. JD7-53) and differentiallock shaft (37) as an assembly from thehousing (7). Remove the bevel pinionshaft (29) and gear (26).

NOTE: Carefully disassemblethe differential fork shaft assem-bly. Spring (35) is compressed.

Use a suitable puller to remove thebearing (42) from the differential case(44). Unscrew the differential case capscrews and remove the case, differen-tial gears (46 and 49) and pinion gears(47).

Inspect components for damage. Theswashplate (2—Fig. JD7-52), washer(3) and bushing (4) are available only asan assembly. The bevel gears (26 and28—Fig. JD7-53) are available only as aset. Gear shaft (29) and ring gear (45)are available only as a set.

Note the following during assembly:The shallow side of the ring gear (45)must contact the differential case (44).The notched side gear (46) fits in thedifferential case. Install the differentiallock fork (33) so the long end of the hubpoints toward the spring (35). Installbushing (11—Fig. JD7-52) so the end isflush with the inside cover surface. Po-sition the spring (8) on the swashplateshaft so the spring ends are crossed andthe spring ends fit the grooves on theeccentric stud (7). Install the seal(12—Fig. JD7-53) with the open sidefacing in.

Apply gasket-forming sealer to thecover and housing mating surfaces. Besure all components remain in placewhen positioning the cover on the hous-ing. Tighten the cover screws to 25 N·m(221 in.-lb.) on a used housing or to 30N·m (22 ft.-lb.) on a new housing.

POWER

TAKE-OFF (PTO)

All models are equipped with apower-take-off that uses a multipledisc, hydraulically actuated clutch toengage the PTO drive train. The PTOshaft extends forward on the final drivehousing underside to connect with themower drive. The PTO clutch transferspower from the hydrostatic transmis-sion input shaft to the PTO drive train.A hydraulically actuated brake pre-vents PTO movement when the PTO isdisengaged.

All models may be equipped with a540 rpm PTO in addition to the stan-dard PTO. The 540 rpm PTO couplerpoints to the rear of the tractor and de-rives power from the standard PTOdrive train. A selector fork directspower to the standard PTO, 540 rpmPTO or both.

HYDRAULIC CIRCUIT

Operation

A small orifice in the hydrostatictransmission lube reduction valveroutes oil to the PTO hydraulic circuit.A pressure control valve maintains cir-

145



Fig. JD7-52–Exploded view of final drive right cover assembly.

1. Washer2. Swashplate3. Thrust plate4. Bushing5. Eccentric adjust

fulcrum

6. O-ring7. Fulcrum screw8. Spring9. Dowel pin

10. Cover11. Bushing

12. O-rings13. Snap ring14. Control arm15. Washer16. Screw17. Washer

18. Nut19. Stud20. Damper21. Washer22. Cotter pin

cuit pressure. An electrically controlledsolenoid controls oil flow to the PTOclutch and PTO brake. Oil pressure en-gages the PTO clutch while simulta-neously releasing the PTO brake. Adrop in oil pressure disengages theclutch and allows the brake spring toactuate the brake.

Testing

To check pto circuit pressure, un-screw plug (6A—Fig. JD7-54) from theupper right-hand port on the transaxlecase and connect a suitable gauge to theport. With the brake engaged and theoperator sitting on the seat, run the en-

gine at wide-open throttle and actuatethe PTO switch. The gauge should read1420-1517 kPa (206-220 psi).

If the gauge indicates the specifiedpressure, but the clutch malfunctions,check the clutch assembly.

If the gauge indicates no pressure orlow pressure, remove the plug(6B—Fig. JD7-54) and check the pres-sure at that port. If the pressure ishigher at the port (B), check the opera-tion of the solenoid control valve. If thepressure is low at both ports, check thepressure control valve. Also check thecharge pump pressure and flow as de-scribed in the HYDROSTATIC TRANS-MISSION section.

ELECTRICAL CIRCUIT

Hydraulic power to the PTO clutch iscontrolled by an electrical solenoid. Theelectrical circuit includes the seatswitch, ignition relay and PTO relay,which interrupt the current flow to thePTO switch and stop the PTO if the op-erator leaves the seat while the PTO isengaged. The circuit also includes abrake switch that will disconnect thecircuit and stop the PTO when thebrake pedal is depressed.

Prior to engaging the PTO, the opera-tor must be in the seat, the PTO switchmust be OFF and the brake pedal mustbe released. To engage the PTO, turn

146



Fig. JD7-53–Exploded view of final drive.

1. Dipstick2. O-ring3. Tube4. O-ring5. Cap6. Vent7. Housing8. Cotter pin9. Washer

10. Lever11. Bracket12. Seal13. Dowel pin14. Input shaft15. Snap ring16. Washer17. Snap ring18. Bearing

19. Snap ring20. Washer21. Snap ring22. Packing23. Bushing24. Oil filter adapter25. Bearing26. Bevel gear27. Snap ring

28. Bevel pinion gear29. Pinion shaft30. Bearing31. Snap ring32. Sleeve33. Differential

lock fork34. Snap ring35. Spring

36. Washer37. Shaft38. Roll pin39. Dowel pin40. Drain plug41. O-ring42. Bearing43. Differential

lock collar

44. Differentialcase

45. Ring gear46. Notched side

gear47. Pinion gear48. Pinion shaft49. Side gear

the key switch to RUN, then turn thePTO switch ON.

When current is available to the PTOrelay, an LED lights on the control/fusemodule (see the ELECTRICAL SYS-TEM section).

Also refer to the wiring schematic atthe end of this section.

PTO Solenoid

To test the solenoid, detach the elec-trical connector (7—Fig. JD7-55). Con-

nect an ohmmeter to the solenoid con-nector. The ohmmeter should indicate amaximum resistance of 0.1 ohms.

To remove the solenoid, disconnect thewiring connector (7) and unscrew thenut (1). Remove the solenoid cover (3)and coil (5). Be careful not to bend, twistor damage the solenoid armature (6),sleeve (10) or spool (11). A special sockettool JDG757A (T) is available for remov-ing the solenoid armature assembly.

Clean and inspect parts for damage.The PTO may not function or function

erratically if the spool, sleeve or arma-ture is damaged. The solenoid coil (5)and armature (6) and the solenoid valve(10 and 11) are available only as assem-blies.

When assembling, be sure the wavewasher (13—Fig. JD7-55) is installed inthe bottom of the bore in the PTO cover.Insert the spool (11) into the sleeve (10)so the end of the spool with the smallhole (H) is toward the large land (L) onthe sleeve. Install the sleeve (10) withthe spool and spring (12) into the coverso the end of the sleeve with the smallerlands goes in first. Use a JDG757Asocket tool to tighten the solenoid ar-mature (6) to 22 N·m (195 in.-lb.). Posi-tion the solenoid coil onto the armatureso the coil leads are facing towards theright side of the transaxle case cover.

NOTE: Tighten the plastic nut (1)to EXACTLY 4.9 N·m (43 in.-lb.).Overtightening the nut will dam-age the armature and/or coil.

PTO Relay

The PTO relay is part of the con-trol/fuse module (see ELECTRICALSYSTEM section). If the voltage checks

147



Fig. JD7-54–Exploded view of PTO brake and drive train. Refer to Fig. JD7-56 for exploded view of PTO clutch.

1. Relief valve2. Gasket3. Spring4. Plunger5. Cover

6A. Plug6B. Plug

7. O-ring10. Clutch assy.11. Brake shoe12. Bearing

13. Washer14. Snap ring15. Washer16. Drive hub17. Bearing18. Snap ring19. Gear20. Shaft21. Washer22. Screw

23. Dowel pin24. Snap ring25. Gear26. Bearing27. PTO shaft28. Screw29. Washer30. Bearing31. Seal32. Bushing

33. O-ring34. Shaft35. Piston36. O-ring37. Snap ring38. Spring39. Spring40. Spring41. Cover42. Screw

Fig. JD7-55–Exploded viewof PTO solenoid valve. As-semble spool and sleevewith small hole (H) in spooltoward large land (L) end ofsleeve.

1. Nut2. O-ring3. Cover4. O-ring5. Solenoid coil6. Solenoid armature7. Electrical connector8. O-ring9. Gasket

10. Sleeve11. Valve spool12. Spring13. Wave washer

indicate the PTO relay is faulty, thecontrol/fuse module must be replaced.

PTO BRAKEOVERHAUL

Both the brake and the PTO clutchmust be removed due to engagement ofthe brake shoe with the PTO clutch.Drain oil from the final drive housing.Remove the rear fender and fuel tank.Remove the rear hitch plate. Discon-nect the electrical connector from thePTO solenoid on the rear cover. Onmodels with 540 rpm PTO, remove therear PTO assembly as described in the540 RPM PTO section. On models with-out a 540 rpm PTO, remove the rearcover (5—Fig. JD7-54).

NOTE: The cover (41) isspring-loaded by brake springs.

Unscrew the brake cover (41) screwsevenly to release spring tension on thecover. Remove brake components(32-40). Remove the PTO clutch (10)with the brake shoe (11). Be careful notto lose the needle bearing and washeron the input shaft.

Inspect components for damage.Check the piston (35) and rod (34) forscoring and burrs. Replace the brakeshoe if the grooves on the contact sur-face are worn smooth. Piston, rod andsprings are available only as a unit.

Reverse the disassembly procedureto reassemble the brake. Apply gas-ket-forming sealer to the cover andhousing mating surfaces. Before tight-ening the screws, be sure the brakecover is properly aligned. Tighten thecover screws evenly to prevent cocking.Tighten brake cover screws to 25 N·m(18 ft.-lb.) on a used housing or to 30N·m (22 ft.-lb.) on a new housing.

PTO CLUTCH AND GEARSOVERHAUL

Models Without 540 rpm PTO

Both the brake and PTO clutch mustbe removed due to engagement of thebrake shoe with the PTO clutch. Re-move the PTO brake, as well as thePTO clutch (10—Fig. JD7-54), as de-scribed in the PTO BRAKE section. Re-move the PTO idler gear assembly(17-21) and PTO gear (25).

NOTE: Left axle passes over thenecked section of the PTO out-put shaft (27). Remove the leftaxle before withdrawing the out-put shaft from the housing.

Inspect components for damage. Theidler (19) and shaft (20) are availableonly as a unit.

Push against the lettered end of thebearing (30) during installation. Installthe seal (31) with the open side towardthe inside of the housing. Install thegear (25) with the wide side of the hubtoward the bearing (26).

Refer to Fig. JD7-56 for an explodedview of the clutch assembly. To disas-semble the clutch, detach the snap ring(17), then remove the clutch plates. Usea suitable compressor to compress thespring (9), then detach the snap ring (11)and remove the remainder of the clutchcomponents. To measure the clutchplate wear, place the clutch discs (14, 15and 16) and snap ring (17) in the clutchhousing (5). Position the clutch housingon a flat surface so the gear end is up.Measure the gap between the top clutchplate and closed end of the slot in theside of the housing as shown in Fig.JD7-57. Replace the clutch plates if thegap is 2.7 mm (0.10 in.) or more. Theclutch plate components (12-16—Fig.JD7-56) are only available as a set.

Apply gasket-forming sealer to thecover and housing mating surfaces. Besure all components fit properly in thehousing and rear cover before tighten-ing the cover retaining screws. Tightenthe rear cover screws to 25 N·m (18ft.-lb.) on a used housing or to 30 N·m(22 ft.-lb.) on a new housing.

Models With 540 rpm PTO

The tractor may be equipped with amanually operated 540 rpm PTO

mounted on the final drive housing rearcover. A shift collar selects the powerflow to the front PTO, 540 rpm PTO orboth.

Drain oil from the final drive hous-ing. Remove the rear fender and fueltank. Disconnect the PTO manual con-trol rod. Remove the rear hitch plate.Disconnect the electrical connectorsfrom PTO solenoid and switches. Re-move the final drive rear cover(47—Fig. JD7-58), on which the 540PTO unit is mounted.

NOTE: Four long screws aroundthe 540 PTO cover (30) also se-cure the rear cover to the finaldrive housing.

Remove the PTO cover (30). Refer toFig. JD7-58 and disassemble as needed.Note the detent ball (39) isspring-loaded and will be free when theshift fork (41) is removed from the shift

148



Fig. JD7-56–Exploded view of PTO clutch.

1. Seal ring2. Bearing3. Washer4. Snap ring5. Clutch housing6. Shaft

7. O-ring8. Piston9. Spring

10. Washer11. Snap ring12. Pin (3)

13. Spring (9)14. Steel plates15. Friction plates16. Steel plate

(thick)17. Snap ring

Fig. JD7-57–Measure gap between topclutch and closed end of slot in side of PTOhousing. Replace clutch plates if gap is 2.7mm (0.10 in.) or more.

shaft (44). The PTO clutch and remain-ing PTO drive components are thesame as used on units not equippedwith a 540 rpm PTO. Refer to the previ-ous section.

Inspect components for damage. Therear PTO input gear (36), shift collar(38) and PTO idler gear (50) are ser-

viced as a set. The rear PTO gear (21)and PTO idler pinion (52) are availableonly as a set.

Install the shift collar (38) so the endwith the outer groove will be toward thecover (30). Be sure the detent ball (39)properly engages the grooves on theshift shaft (44). Install the seal (14)

with the open side toward the inside ofthe cover (30). Push the bearings (32and 34) against the shoulder on theshaft (33). Install the gear (21) so thewide side of the hub is toward the bear-ing (22).

Apply gasket-forming sealer to themating surfaces of the PTO cover (30)

149



1. Snap ring2. Splined sleeve3. Bearing4. Gear5. Bearing6. Spacer7. Snap ring8. Snap ring9. Bearing

10. Front PTOshaft

11. Screw12. Washer13. Bearing14. Seal15. Coupler16. Cap17. Snap ring

18. Washer19. Ball bearing20. Snap ring21. Gear22. Bearing23. Snap ring24. Washer25. Balls (3)26. Bushing

27. Spring28. Washer29. Switches30. Cover31. Bushing32. Bearing33. Shaft34. Bearing35. Snap ring

36. Gear37. Snap ring38. Shift collar39. Detent ball40. Spring41. Shift fork42. O-ring43. Shift lever44. Shaft

45. Screw46. Plate47. Housing48. Bearing49. Washer50. Gear51. Shaft52. Gear

Fig. JD7-58–Exploded view of 540-rpm PTO assembly.

and the final drive housing cover (47).Be sure all components fit properly inthe housing and cover before tighteningthe cover retaining screws. Tighten therear cover screws to 25 N·m (18 ft.-lb.)on a used housing or to 30 N·m (22ft.-lb.) on a new housing.

Apply gasket-forming sealer to the fi-nal drive housing and housing cover(47) mating surfaces. Be sure all com-ponents fit properly in the housing andcover before tightening cover retainingscrews. Tighten screws to 25 N·m (221in.-lb.) on a used housing or to 30 N·m(22 ft.-lb.) on a new housing.

HYDRAULIC SYSTEM

SYSTEM OPERATION

All models are equipped with a hy-draulic system shown in Fig. JD7-59.The charge pump mounted on the frontof the hydrostatic transmission pro-vides pressurized oil for the transmis-sion, PTO, hydraulic lift and powersteering systems. The hydraulic systemuses oil contained in the final drivehousing. Oil from the housing sumppasses through a filter, then to thecharge pump. Pressurized oil from thecharge pump travels internally to thetransmission and PTO. An implementrelief valve on top of the transmissionvalve block protects the system fromexcessive pressure.

Outlet oil from the charge pump trav-els to the power steering control valveand hydraulic lift circuits. Hydraulic oilat the control valve may be directed tooperate the hydraulic lift cylinder or topower accessories through hydrauliccouplers. Return oil from the steeringvalve and hydraulic control valvepasses through an oil cooler in the radi-ator. Some models are equipped with ashutoff valve isolating the lift cylindercircuit for more positive action from ac-cessories connected to hydraulic cou-plers.

Also refer to the POWER STEERINGand TRANSMISSION sections.

TESTING

Pressure Testing

To check system pressure, connect apressure gauge to a hydraulic coupler.Run the engine at full throttle. Movethe hydraulic lift control lever to raiseor lower the position so the relief valveoperates. Maximum pressure should be6371-7350 kPa (924-1065 psi).

Inadequate pressure may indicate amaladjusted relief valve, faulty chargepump, plugged modulation orifice inlube reduction valve, or excessive leak-age in transmission pump. Refer to the

TRANSMISSION section and performcharge pump tests.

Flow Test

Attach a suitable thermometer to thespin-on filter to monitor oil tempera-ture. It may be necessary to block theairflow through the radiator to raise oiltemperature.

Connect a flowmeter to the hydrauliccouplers. Check the oil flow with the en-gine running at full throttle and oiltemperature at 110° F (43° C). Move thehydraulic control lever to raise or lowerposition to obtain proper oil flow direc-tion on gauge. Normal oil flow is 17.0L/m (4.5 gpm). The minimum allowableoil flow is 13.0 L/m (3.5 gpm).

Note the test does not isolate the spe-cific problem, which may be in thecharge pump, power steering or hy-draulic lift circuit.

HYDRAULIC CONTROL VALVE

Leak Test

To check the control valve for leak-age, operate unit until oil reaches nor-mal temperature. Operate thehydraulic control lever to fully extendthe piston rod (raise position), then stopthe engine. Disconnect the return hy-draulic line from the control valve. Holdthe lift control valve in raise positionand start engine.

NOTE: Do not move the hydrau-lic control lever to neutral withthe engine running because fullhydraulic flow will dischargefrom control valve port.

There should be no more than a dripfrom the control valve port. Reconnectthe return line.

Operate the hydraulic control leverto fully retract the piston rod (lower po-sition), then stop engine. Disconnectthe return hydraulic line from the con-trol valve. Hold the lift control valve inthe lower position and start engine.

NOTE: Do not move the hydrau-lic control lever to NEUTRALwith the engine running becausethe full hydraulic flow will dis-charge from the control valveport.

There should be no more than a dripfrom the control valve port. Reconnectreturn line.

Replace the control valve if leakage isexcessive in either test.

Overhaul

Remove the radiator as previouslydescribed. Remove the footrest/consolepanel. Detach and remove the controlvalve (8—Fig. JD7-59). Rotate thevalve as necessary to disconnect the

150



Fig. JD7-59–Diagram showing hydraulic system components and hydraulic oil flow.

6. Radiator/oil cooler7. Hydraulic couplers8. Lift control valve9. Power steering

cylinder

1. Lift cylinder2. Charge pump3. Auxiliary control lever4. Lift control lever5. Shutoff valve

10. Final drive11. Oil filer12. Hydrostatic transmission13. Power steering

control valve

links. Plug or cap the openings to pre-vent contamination.

To disassemble, remove the loadcheck valves (5-8—Fig. JD7-60). Theload check valves are serviced as an as-sembly kit. Remove the detent springs(26) and balls (27) before removing theend cap (24). Spools (1 and 2) are

matched to the bores in the valve bodyand must be used in the original bores.Spools and valve body are availableonly as a unit assembly.

Apply multipurpose grease to detentsprings and balls during assembly. Ap-ply multipurpose grease to springs (12and 20) during assembly. Apply Loctite

to the end cap retaining screws andtighten screws to 4 N·m (36 in.-lb.).Tighten spool detent (22) to 4 N·m (36in.-lb.).

Reinstall control valve by reversingthe removal procedure.

HYDRAULIC CYLINDER

To check cylinder seals for internalleakage, first fully extend the pistonrod (raise position), then stop the en-gine. Disconnect the hydraulic line atcontrol valve connecting to the rod endof the cylinder. Hold the lift controlvalve in the raised position and startengine.

NOTE: Do not move hydrauliccontrol lever to NEUTRAL whilethe engine is running becausethe full hydraulic flow will dis-charge from the control valveport.

There may be an initial flow of oil outthe open hydraulic line, then the oilflow should stop. If oil continues to flow,the cylinder piston seal is faulty.

Hydraulic cylinder is a welded as-sembly and no service parts are avail-able. Replace the cylinder if internal orexternal leakage is apparent.

ELECTRICAL SYSTEM

Some engine electrical componentsare covered in the engine service sec-tion. If service information is not foundin this section, refer to the appropriateengine service section.

BATTERY

The tractor is equipped with a 12volt, group U1 battery. On Models 425and 445, the cold cranking amp ratingis 342 amps with a reserve capacity of44 minutes. On Model 455, the coldcranking amp rating is 470 amps with areserve capacity of 76 minutes.

ELECTRIC STARTER

Models 425 and 445

An exploded view of electric starter isshown in Fig. JD7-61. Place alignmentmarks on the pinion housing (1), fieldcoil frame (9) and end cover (13) beforedisassembly so they can be reinstalledin its original position. Remove the so-lenoid (3). Unscrew the through-bolts(14) and separate drive housing, endcover and brush holder (10) from thefield coil frame (9).

Replace the brushes (11) if the lengthis less than 6 mm (0.24 in.). The starterno-load current draw should be 50

151



Fig. JD7-60–Exploded view of selective control valve.

1. Lift spool2. Auxiliary spool3. Plug4. O-ring5. Check valve cap6. O-ring7. Spring8. Poppet9. Housing

10. O-ring

11. Washer12. Spring13. Retainer14. Screw15. Gasket16. Cap17. Washer18. Screw19. Washers20. Spring

21. Retainer22. Spool detent23. Gasket24. Cap25. Plug26. Spring27. Check ball28. Washer29. Screw

Fig. JD7-61–Exploded view of starter used on Models 425 and 445.

1. Drive housing2. Fork3. Solenoid4. Washer5. Pinion stop

6. Snap ring7. Clutch assy.8. Armature9. Frame

10. Brush plate

11. Brushes12. Springs13. End cap14. Through-bolt

amps at starter speed of 6000 rpm.Starter current draw under load shouldbe 72 amps at starter speed of 500 rpm.

Model 455

Refer to the Yanmar ENGINE SER-VICE section for the starter motor ser-vice instructions.

ALTERNATOR

Models 425 and 445

The alternator stator is located underthe flywheel. To check alternator, dis-connect stator from the regulator/recti-fier (Fig. JD7-62), and check thevoltage reading at the stator leads.With the engine running at full speed,the minimum voltage reading is 26volts AC.

Model 455

Refer to the Yanmar ENGINE SER-VICE section for the alternator serviceinstructions.

REGULATOR/RECTIFIERTESTING

Models 425 and 445

The following tests are performedwith the wire connector attached to theregulator/rectifier. When performingvoltage tests, connect the negative volt-meter lead to the negative battery ter-minal. Insert the voltmeter positivelead into the specified wire connector(do not disconnect wire). Run the en-gine at the fast idle. Battery voltagemust be 11.8-13.2 V. Battery voltagemust be present at the red connectorwire 5—Fig. JD7-62).

Check voltage at the brown/whiteconnector wire (2). The voltmetershould read 26 V AC, if not check the al-ternator.

Check voltage at the black connectorwire (4). The voltage should be greaterthan 0 but less than 0.2 V. If the voltageis greater than 0.2 V, check the groundcircuit. If the voltage is zero, the regula-tor/rectifier is faulty.

Check the current at the red connec-tor wire (5) using an ammeter. If theamperage is less than 13 amps, the reg-ulator/rectifier is faulty.

Model 455

The following tests are performedwith the wire connectors attached.When performing voltage tests, connectthe negative voltmeter lead to the nega-tive battery terminal. Insert the volt-meter positive lead into the specifiedwire connector (do not disconnect wire).Battery voltage must be 11.8-13.2 V.Battery voltage must be present at each

of the number 3 (Fig. JD7-63) termi-nals.

Turn the key switch ON and checkthe voltage at the dash panel moduleterminal 4 (yellow wire). Voltage shouldbe greater than 0 but less than 0.2 V. Ifvoltage is greater than 0.2, check thecharge lamp ground circuit. If voltage iszero, check the charge indicator bulb. Ifthe bulb is not faulty, replace the dashpanel module.

To determine whether the regula-tor/rectifier or alternator is faulty, con-duct the following tests. If the unit failsvoltage test and passes the amperagetest, the regulator/rectifier is faulty. Ifthe unit fails both tests, the alternatoris faulty (regulator/rectifier may befaulty as well).

To check regulated voltage, partiallydischarge the battery. Run the engineat fast idle and monitor the voltage atthe alternator red wire.

NOTE: To prevent damage, donot allow battery voltage to ex-ceed 15.5 V.

Regulated voltage should be12.2-14.7 V. If voltage is less than speci-fied, alternator or regulator is faulty. Ifvoltage exceeds 14.7 V, replace the reg-ulator. Note that the regulator is con-

tained in the alternator housing onModel 455.

To check the alternator unregulatedamperage output, connect the ammeterto the red output wire (A—Fig. JD7-64).The alternator must be properlygrounded and the battery voltage mustpresent at the alternator regulator ter-minal.

NOTE: To prevent damage, donot perform the test longer than10 seconds.

Start the engine. While running en-gine at 3350 rpm, insert a Phillipsscrewdriver through the rear hole (B) inthe alternator rear cover as shown inFig. JD7-64 and ground the regulator.The ammeter should indicate as least35 amps, otherwise the alternator isfaulty. If the voltage is less than speci-fied, either the alternator or regulatoris faulty. If the voltage exceeds 14.7 V,replace the regulator. The regulator iscontained in the alternator housing onModel 455.

CONTROL/FUSE MODULE

All models are equipped with a con-trol/fuse module serving as the mount-ing base for the fuses, relays, LEDs andassociated circuitry. No components are

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Stator

Regulator/rectifier

BLK

BRN/YEL

BRN/WHT

BLK

YEL

RED

BRN

Fig. JD7-62–Refer to text to test regulator/rectifier used on Models 425 and 445.

available separately, except fuses. Ma-jor components mounted on the moduleinclude the following:

An LED (4—Fig. JD7-65) lights whenpower is available to the ignition relay(5) on Models 425 and 445. On Model455, LED (4) indicates power is avail-able to the hold-in relay (5), whichholds the plunger of fuel shutoff sole-noid in operating position.

The LED (3) lights when power isavailable to the PTO relay (8).

NOTE: Unlit LEDs are not an in-dication of a faulty module, onlythat current is not reaching theLED.

The start relay (2) directs current tostarter motor when key switch andsafety switches are closed.

The fuse (6) is rated 15 amps and pro-tects the main power circuit. The fuse(7) is rated 15 amps and protects theheadlight circuit.

Testing

The following tests will help deter-mine if a module component or the as-sociated circuit is causing an electricalproblem.

Before conducting tests, be sureground connections are good (terminalD—Fig. JD7-66 is ground) and the bat-tery is fully charged. The fuses must begood. Turn the key switch OFF, disen-gage the PTO, shift the transmission toNEUTRAL, and engage the parkingbrake. Defeat the seat switch by jump-ing connector wires or by placing aweight on the seat.

Connect the negative voltmeter leadto the negative battery terminal. Con-nect the positive voltmeter lead to theterminals indicated in the following ta-ble. In each test, the voltmeter shouldindicate battery voltage. Conduct thetests with the key switch in the ON po-sition. Refer to Fig. JD7-66.

2 (red wire) Power circuit3 (red wire) Power circuit3 (red/black wire-

Model 455) Power circuit4 (yellow wire) Module (if fuses OK)5 (pink/black wire) Neutral start circuit6 (pink wire) Seat switch circuit7 (pink/black wire) Module8 (yellow/blue wire) Module

Disengage the parking brake for thenext tests.

9 (purple wire) Pto relay engagementcircuit

10 (blue wires) Module

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506YEL

600BRN

505YEL

190BLK

295Red

Fig. JD7-63–Refer to text to test regulator/rectifier used on Model 455.

Fig. JD7-64–Refer to text totest unregulated amperageoutput of alternator used onModel 455.

Fig. JD7-65–Drawing of con-trol/fuse relay.

1. Module2. Start relay3. PTO LED4. Ignition LED

(Models 425-445)4. Hold-in LED

(Model 455)5. Ignition relay

(Models 425-445)5. Hold-in relaty

(Model 455)6. Power circuit fuse

(15 amp)7. Headlight circuit

fuse (15 amp)8. PTO relay9. Power connector

10. Control connector

Engage the parking brake. Discon-nect the starter solenoid wire. Turn thekey switch to the START position. Mea-sure the voltage at terminal 11 (purplewire). If the voltmeter indicates batteryvoltage, replace the module.

DIESEL CONTROL MODULE

In addition to the control/fuse mod-ule, Model 455 is equipped with a dieselcontrol module. Two relays, the fuelshutoff pull-in relay (A—Fig. JD7-67)and the glow plug relay (B), aremounted on the module printed circuitboard.

The pull-in relay energizes the fuelshutoff solenoid pull-in winding for 1second. Refer to the FUEL SHUTOFFSOLENOID section.

The glow plug relay routes current tothe engine glow plugs for 45 seconds.

Diesel control module must be ser-viced as a unit assembly.

Condition of the relays may bechecked by referring to the wiring sche-matic and performing voltage tests, aswell as listening for clicking soundwhen relay operates.

Testing

The following tests will help deter-mine if an electrical problem is causedby a module component or the associ-ated circuit.

Before conducting tests, be sure thegrounds connections are good and thebattery is fully charged. Fuses on con-trol/fuse module must be good. Turn thekey switch OFF, disengage the PTO,shift the transmission to NEUTRALand engage the parking brake. Defeatthe seat switch by jumping the connec-tor wires or by placing a weight on theseat.

Connect the negative voltmeter leadto the negative battery terminal. Con-nect the positive voltmeter lead to theterminals in the following table. Ineach test, the voltmeter should indicatebattery voltage. Conduct the tests withthe key switch ON. Refer to Fig.JD7-67. The letter after the terminalnumber indicates left (L) or right (R)connector.

Terminal Fault

2L (pink and brown wires) Control/fusemodule power circuit3L (pink/blue and blue wires) Fuel shutoffsolenoid relay

hold-in circuit

4R (red wire) Power circuit5R (red wire) Power circuit6R (red/black wire) Power circuit

Turn the key switch OFF and ON re-peatedly while performing the follow-ing tests. At terminals 7 and 8, thevoltmeter should indicate battery volt-age for up to 45 seconds. At terminal 9,the voltmeter should indicate batteryvoltage for up to 1 second.

Terminal Fault

7R (white wire) Module8R (red/white wire) Module9R (white wire) Module

Check voltage at terminal 10 (greyand orange/white wires) while turningkey switch OFF and ON repeatedly.The voltmeter should indicate voltagegreater than zero but less than 1 V forup to 20 seconds. If voltage exceeds 1 V,replace the diesel control module.

FUEL SHUTOFF SOLENOID(MODEL 455)

The fuel shutoff solenoid holds thefuel injection pump linkage in theclosed position until the battery voltageenergizes the solenoid. The solenoidthen moves the pump linkage so thefuel pump delivers fuel to the engine. Apull-in winding moves the solenoidplunger, and a hold-in winding holdsthe plunger in position.

Separate relays control current to so-lenoid windings. Current for hold-inwinding must pass through safetyswitches to the hold-in winding relay

before reaching the solenoid. Currentfrom the hold-in winding relay alsotravels to a pull-in winding relay timer,which sends current for 1 second to thepull-in winding relay. The pull-in relayenergizes the solenoid pull-in windingfor 1 second, the hold-in winding main-tains the plunger position and thepull-in timer stops current to thepull-in relay.

An LED on control/fuse module (Fig.JD7-65) lights when the current isavailable to the hold-in winding relay.

To check the fuel shutoff solenoid andlinkage, measure amperage throughthe wires for the pull-in and hold-inwindings with the solenoid installed.Be sure the voltage reaches the sole-noid. Maximum amperage readings are1 amp continuous for the red hold-inwinding wire and 50 amps for 1

2 secondfor the pull-in winding wire (white). Ex-cessive readings indicate faulty wind-ings or binding.

WIRING DIAGRAMS

Refer to Fig. JD7-68 for Models 425and 445 electrical system componentlocation. Refer to Fig. JD7-69 for Model455 electrical system component loca-tion. The electrical system wiring dia-gram for Models 425 and 445 isillustrated in three sections (Fig.JD7-70A-Fig. JD7-70C). The electricalsystem wiring diagram for Model 455 isillustrated in two sections (Fig.JD7-71A and Fig. JD7-71B).

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10BLU

2RED

11PUR

4YEL

8YEL/BLU

3RED

RED/BLK

7PNK/BLK

BLU

5PNK/BLK

6PNK

9PUR

10BLU

Fig. JD7-66–Refer to text for control/fusemodule test procedure.

1BLK

2PNKBRN

10GRY

ORG/WHT

3PNK/BLU

BLU

4RED

5RED

6RED/BLK

9WHT

7WHT

8RED/WHT

Fig. JD7-67–Refer to text for diesel controltest procedure.

Fig. JD7-68 through JD7-71C are on the following pages.

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Fig. JD7-68–Drawing showing electrical system component location for Model 445. Model 425 is similar except for fuel injection compo-nents.

1. Regulator/rectifier2. Fule pump relay3. Fuel injection relay4. Fuel injection fuse5. Safety relay6. Control/fuse module7. Brake switch8. Air temperature sensor9. Pulser coil

10. Spark plug, R.H.11. Ignition coil, R.H.12. Oil pressure switch

13. Headlight14. Stator15. Positive battery cable16. Engine ground17. Battery18. Negative battery cable19. Starting motor20. Ignition coil, L.H.21. Coolant temperature switch22. Spark plug, L.H.23. Fuel injector24. Air pressure sensor

25. Coolant temperature sensor26. Fuel injection module27. Dash panel connector28. Dash panel module29. PTO switch30. Light switch31. Key switch32. Seat switch33. PTO solenoid34. Tailight35. Fuel gauge sensor36. Fuel pump

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Fig. JD7-69–Drawing showing Model 455 electrical system component location.

1. Fuel pump2. Fuel gauge sender3. Diesel control module4. Fuel pump fuse5. Control/fuse module6. Engine high temperature relay7. Alternator8. Coolant temperature switch9. Fuel shutoff solenoid

10. Starting motor11. Positive battery cable12. Engine ground13. Battery14. Negative battery cable15. Oil pressure switch16. Glow plugs17. Coolant temperature sensor18. Headlight

19. Brake switch20. Dash panel module21. Dash panel connector22. PTO switch23. Light switch24. Key switch25. Seat switch26. Taillight

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Fig. JD7-70A–Partial wiring schematic for Model 445. Model 425 is similar. Refer to Fig. JD7-70B and Fig. JD7-70C.

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Fig. JD7-70B–Partial wiring schematic for Model 445. Model 425 is similar.

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Fig. JD7-70C–Partial wiring diagram for Model 445. Model 425 is similar.

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Fig. JD7-71A–Partial wiring schematic for Model 455. Refer also to Fig. JD7-71B and Fig. JD7-71C.

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Fig. JD7-71B–Partial wiring diagram for Model 455.

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Fig. JD7-71C–Partial wiring schematic for Model 455.

John Deere YARD & GARDEN TRACTORS JOHN DEERE

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