Assambly Procedure for Connecting Rod Big End

Service, Wärtsilä Finland Oy Käyttöohje Driftsinstruktion

Engine section Engine type Ref. Date Issue Document No. Page11 Crank mechanism W20 WFI�S 19.01.2004 01 2011Q002GB 1(3)

Wärtsilä Finland Oy P.O. Box 252 (Tarhaajantie 2) Telecop. +358 10 709 7355 Tel. +358 10 709 0000 Business ID 0773744-3Service, Vaasa FIN-65101 Vaasa, Finland Telecop. +358 6 356 7339 Registered Office: Vaasa

Wärtsilä Finland Oy P.O. Box 50 (Stålarminkatu 45) Telecop. +358 10 709 3279 Tel. +358 10 709 0000Service, Turku FIN-20811 Turku, Finland Telecop. +358 10 709 3410

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Assembly procedure for connecting rod big endEngine type This Operating Instruction concerns all WÄRTSILÄ� 20 engines.

Background It is essential to pay attention to the dismantling and assembly procedure ofthe connecting rod because an incorrect assembly procedure can be adirect reason for a failure at the big end of the connecting rod.

Therefore the Instruction Manual has been revised accordingly. See section11 enclosed.

Revised routines The following assembly routines have been revised:

• Check clearance between the engine block and the distance sleevesafter turning the crankshaft to a crank angle of about 55º from top deadcenter (TDC) towards the operating side for the cylinder concerned. Seesections 11.4.3 and 11.4.5.

• Lubricate the back side and the end faces of the big end bearing shellsto ensure proper bed in of the bearing shells in the bore. See section11.4.5.

Caution: Any use of glue on a bearing shell is prohibited!

Operating side

Check the clearance !


Service, Wärtsilä Finland Oy Operating instruction

Issue Document No. Page01 2011Q002GB 2(3)

• Check the bearing shell alignment in the connecting rod beforetightening to ensure that the bearing shells are mounted straight in thebig end bore. See section 11.4.5.

• Check of the exposed connecting rod screw section which is valid onlyfor the connecting rod screw with an end plug. The referencemeasurement is for guidance only and will reveal the condition of theend plug. See section 11.4.5 and Technical bulletin 2011T004.

Caution:- An end plug may under no circumstances be used with the

270 mm long connecting rod screw.- Check that no plug remains in the threaded holes of the

connecting rod before mounting the screws.

Connecting rod screw Replacement recommendation for the connecting rod screw is at latestevery 24000 hours. See Technical Bulletin 2011T004.

Standard routines Wärtsilä would also like to emphasize a few important routines mentionedunder �Dismantling and Reassembling hydraulically tightened screwconnection�. See chapter 07.3.3 and 07.3.4 in your Engine InstructionManual.

• Expel (return) possible oil from the hydraulic cylinders always back tothe pump before the tools are taken into use at dismantling andreassembling.

• Be aware of the correct turning direction when loosening or tighteningthe screw nut.

� On loosening turn the nut counter-clockwise (CCW)� On tightening turn the nut clockwise (CW)

• To ensure proper hydraulic tightening, raise the pressure in two stepsi.e. pump the pressure to 300 bar and turn the nut in a clockwisedirection until it has a contact with the connecting rod cap. Increase thepressure further to stated pressure. Turn the nut until it has a closecontact with the face again. This time the nut should move just a limitedangle, but approximately the same angle for all nuts of the same kind.

Service, Wärtsilä Finland Oy Operating instruction

Issue Document No. Page01 2011Q002GB 3(3)

50 hrs maintenance Check the tightening of the connecting rod screws after the first 50operating hours on a new engine and after overhaul. See chapter 04.4.

Tool maintenance The hydraulic tool set should be stored in a suitable place and corrosionprotected. The set should be regularly checked and worn or damaged partsreplaced. See chapter 07.3.2. Special attention should be paid to thefollowing components.

• Pressure gauge: Regularly calibration checked.

• Hydraulic couplings and hoses: Condition check

• Hydraulic pump: Condition check.

• Hydraulic cylinder o-ring: Wear and condition check.

Note! If the hydraulic cylinder o-ring has been exposed outside the cylinderthe oil has to be removed from the cylinder before the cylinder with the o-ring can be re-installed. To return the o-ring with the oil in the cylinder willonly damage the o-ring. It is prohibited to use a malfunctioning hydraulictool.

Recommendation Replace the old chapters in the Engine Instruction Manual with the new,implement them in the maintenance schedule and follow the revisedassembly and maintenance routines.

Warranty Unless otherwise expressly set forth, no recommendation contained in thisdocument is to be construed as provided due to a defect in the engine, butmerely as an improvement of the engine and/or the maintenanceprocedures relating thereto. Any actions by the owner/operator as a resultof the recommendations are not covered under any warranty provided byWärtsilä and such actions will thus be at the owners/operators own cost andexpense.

Letter distribution Wärtsilä Service Network and owners/operators of WÄRTSILÄ� 20engines.

Letter validity Until further notice.

Enclosure Chapter 11 of the Instruction Manual.

� 2004 Wärtsilä Finland Oy � All rights reserved

No Part of this publication may be reproduced or copied in any form or by any means (electronic, mechanical, graphic, photocopying,recording, taping or other information retrieval systems) without the prior written permission of the copyright holder. Wärtsilä Finland Oymakes no representation, warranty (express or implied) in this publication and assumes no responsibility for the correctness, errors oromissions for information contained herein. Information in this publication is subject to change without notice.

NO LIABILITY WHETHER DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL, IS ASSUMED WITH RESPECT TOTHE INFORMATION CONTAINED HEREIN. THIS PUBLICATION IS CONFIDENTIAL AND INTENDED FOR INFORMATIONPURPOSES ONLY.

11. Crank Mechanism: Crankshaft, Connecting Rod, Piston

11.1 Crankshaft

11.1.1 Description of crankshaft

Data and dimensions Material: Forged, alloyed

steelWeight: 750 kg (4L20)

770 kg (5L20) 790 kg (6L20)1000 kg (8L20)1110 kg (9L20)

The crankshaft is forged in one piece and provided with twocounter-weights per cylinder. The counter-weights are fastenedwith two screws each. 4L20 has integrated counter-weights. At the driving end of the engine, the crankshaft is equipped witha V-ring for sealing of the crankcase. The axial clearance iscontrolled by a combined flywheel/thrust bearing. A shrink fittedgear wheel for driving of the camshaft is located in the drivingend. The main bearings are described in chapter 10. At the free end, there is a gear for driving of water pumps andthe lubricating oil pump. Usually a vibration damper is alsoinstalled (separate instructions for the vibration damper aresubmitted, if the engine is equipped with such). The crankshaft can be turned by a manual turning deviceoperating the flywheel. The lubricating oil is supplied through the side screw holes inthe engine block to the main bearings. The oil flows further fromthe main bearing through the bores in the crankshaft to theconnecting rod big end bearing and up in the connecting rod andpiston. Due to a special design of the bores in the crankshaft, theflow to the connecting rod is intermittent. The oil is forced to flowin one direction only.

11.1.2 Balancing of crankshaft

Data and dimensionsMaterial: Steel plateWeight: 21 kg

The crankshaft is balanced by means of counterweights on thecrank webs, two weights per cylinder. The counter-weights arefastened to the web with two screws (4L20 has integrated counter-weights).

Note! The counterweight shall always be assembled with the guidepin to make sure the right position, see Fig 11-1

20-200349-02 Crank Mechanism 11

WÄRTSILÄ 20 11 - 1

Positions of counterweights

11.1.3 Crankshaft alignment

1 Turn crank of the first cylinder near BDC (bottom deadcentre) and attach the crankshaft dial indicator to the centremarks in the two crank webs. The distance between the indi-cator and the connecting rod should be as small as possible.

2 Set indicator at zero.

3 Read deflections when turning crank to the rear side,TDC (top dead centre), operating side and BDC. Record read-ings in the form “Crankshaft alignment”.

Note! During the alignment procedure the crankshaft should beturned in the anti-clockwise direction, only.

4 Repeat this procedure with other cylinders.

5 Following limits of misalignment are stated for an enginehaving normal running temperature (within 5 minutes afterrunning at 60 % load or higher for 6 h or more):

a) on the same crankThe difference between two diametrically opposed readings mustnot exceed 0.04 mm after installing or realigning. Realignment isnecessary if this limit is exceeded by more than 0.02 mm.

b) on two adjacent cranksThe difference between two corresponding readings must notexceed 0.04 mm. Realignment is necessary if this limit is ex-ceeded.

Cyl. No. 1 2 3 4 5 6

A

A

SECTION A-A

Guide pin

Fig 11-1 3211599601

11 Crank Mechanism 20-200349-02

11 - 2 WÄRTSILÄ 20

c) when the crank pin of cyl. 1 is at TDC (reading C)The reading should be negative, max. -0.04 mm (-0.08 mm if flex.coupling). Before realigning the engine and the driven machinery, a con-trol measurement of the main bearings should be made.

Note! In an engine having a normal ambient temperature, the cor-responding values must be based on experiences from theparticular installation.

Dial indicator position and reading

11.2 Flywheel

11.2.1 General description of flywheel

Data and dimensionMaterial : Steel plateWeight: about 350 kg

The steel flywheel is fitted to the crankshaft with four fittedscrews and four normal screws. The correct position of the fly-wheel is determined by three smaller screws. A gear rim is fitted to the flywheel. A crank angle scale is stamped on flywheel. The scale startsfrom zero for the TDC for cylinder 1 and is divided in 360° crankangle. The TDC is marked for all cylinders. The flywheel position indicator is marked with a scale forreading of the engine crank angles, at an accuracy of one (1) degreecrank angle, on the graduation of the flywheel.

B

C

D

EAOperatingside

Rear side

As seen fromflywheel end

0+

-

107mm

Punched points

Fig 11-2 2011539601



Reading of flywheel indicator

11.2.2 Replacing the gear rim

If the gear rim is damaged or worn it can be replaced withoutremoving the flywheel as follows:

1 Open the screws which are holding the gear rim andremove the gear rim from the flywheel.

2 Cut the ring in suitable pieces. Ensure that the flywheelis not damaged during this operation.

3 The spare part gear rim is delivered in two pieces, which easily can be mounted on the flywheel. Additional screwholes for the ring half ends are premachined at the factory.

4 Mount the gear rim halves and tighten the fasteningscrews to stated torque, see section 07.1.

5 Check the base tangent lenght over the number of teethspanned, see Fig 11-4.

0CYL1, 6TDC

350

340

54321012345

CLO

CK

WIC

E R

OTA

TIN

G E

NG

INE

A

VIEW A

12

Cyl 1 TDC

Fig 11-3 2011690119



Base tangent lenght over the number of teeth spanned

11.3 Turning device

The crankshaft can be turned by a manual turning device oper-ating on the flywheel. The turning device consists of a gear, whichis operated with a ratchet. The rotational direction for turningcan be reversed by altering the ratch position of the ratchet.

Note! The engine must not be started while the turning gear isengaged.

11.4 Connecting rod and piston

11.4.1 General description of connecting rod

Data and dimensionMaterial: Special steel,

drop forgedWeight: 38 kgBearing type: Bi-metal bearing

The connecting rod is of the drop-forged type with H-section shaft.The big end is of “stepped split line” design and precision serratedat the mating surfaces. This design offers the maximum crankpin diameter but still makes it possible to pull the connecting rodthrough the cylinder liner. The big end bearing shells are, for correct assembling, axiallyguided by lugs. The design of the crankshaft enables the use of anon-grooved upper bearing shell. The two connecting rod screws are hydraulically tightened. The gudgeon pin bearing bush is stepped to give a larger bearingsurface on the more loaded lower side. It is lubricated via boresin the connecting rod. The gudgeon pin is of the full floating design, secured axiallywith retainer rings. The oil flow from the connecting rod is passedthrough the gudgeon pin further up to the piston. The gudgeonpin has shrink fitted plugs in the ends.

W/k = 317.748 -0.320-0.640 / 30

1. Gear rim half 1

Fig 11-4 3211549418



11.4.2 General description of piston

Data and dimensionComposite pistonMaterial skirt: Nodular cast iron

or forged steelMaterial crown: Forged steelScrew: 10.9Weight: 22 kg

The piston is of composite type with a forged steel or a nodularcast iron skirt and a forged steel crown screwed together. Thepiston skirt has a phosphate/graphite overlay. The piston crown is cooled with lubricating oil by means of thecocktail shaker effect. The lubricating oil is led from the mainbearing, through the bores in the crankshaft, to the big endbearing, and further through the bores in the connecting rod,gudgeon pin and piston skirt, up to the cooling space, from whereit is drained back to the oil sump. The pistons are provided with Wärtsilä patented skirt lubricat-ing system. The combustion chamber in the top of the piston is deep,preventing the fuel jets to touch the cylinder liner. The compression ring grooves are hardened for better wearresistance.

Note! Always handle the pistons with care. Do not damage or re-move the phosphate/graphite overlay.

The piston ring set consists of two compression rings and onespring-loaded oil control ring. In this three-ring pack, every ringis specially dimensioned and profiled for the task it has to per-form. The top ring is provided with a special wear resistantcoating. The second compression ring is chrome-plated. The oilcontrol ring is a spring-loaded, chrome-plated oil scraper ring. The side to be upwards of the compression rings is alwaysmarked “TOP”.

11.4.3 Removing and dismantling of piston andconnecting rod

Data and dimensionWeight: 75 kg 1 Remove the cylinder head,see chapter 12 section 12.2.1

Scrape off carbon deposits carefully from the slots of the anti-polishing ring and around the upper part of the cylinder liner.It is advisable to cover the piston top with cloth or paperpressed tightly (by an old piston ring) against the cylinder wallto collect the deposits removed.

2 Remove the anti-polishing ring. Use the tool 836002 toextract the ring and 836003 to keep the liner in place duringthe extracting procedure. By turning the engine, the pistonpushes the anti-polishing ring out.

3 Clean the threaded hole in the piston crown and fastenthe lifting tool 832002.

4 Turn the crankshaft about 55° from TDC towards the op-erating side for the cylinder concerned, see Fig 11-5.

836 003

836 002



5 Lift the distance sleeves 861153 into position on the con-necting rod screws and screw on the hydraulic tools 861159with extension pieces 861157.

Note! Check that there is clearance between the distance sleevesand the engine block, before and after applying the pressureon the hydraulic tool. If necessary turn the crankshaft slightlyto get the clearance for both sleeves.

Dismantling of piston and connecting rod

6 Connect the hoses of the hydraulic pump and proceedto open the connecting rod nuts, see chapter 07., section 07.3

7 Remove the hydraulic tool and the distance sleeve from the connecting rod studs.

8 Open the lower nut and remove the lower stud usingthe stud extracting tool 803011. The locking screw of the toolhas left-hand threads.

9 Repeat the same procedure as above with the uppernut and stud and lift the big end bearing cap together withthe bearing shell out of the engine.

Hydraulic oil

DISMANTLING1. Screw on cylinders by hand2. Connect hoses, open valve. Tighten cylinders by hand.

3. Screw cylinders 180° counter -clockwise.4. Close valve, rise pressure.5. Open the nut about half a turn.6. Open release valve, remove tool.

861 153 Distance sleeve861 157 Extension piece861 159 Hydraulic cylinder832 002 Lifting tool for piston

861 159

861 153

861 159

861 157

Operating side

832 002



Fig 11-5 2011750240



10 Lift the piston a little to remove the upper big endbearing shell. When lifting the piston, take care not to dam-age the crank pin or the cylinder liner wall.

11 Cover crank pin oil holes with tape.

12 Lift the piston together with the connecting rod out of theengine. When lifting the piston, take care not to damage thecylinder liner wall.

13 Remove the retainer ring from the gudgeon pin hole inthe piston, on the side where the gudgeon pin drawing numberis located, by using the pliers for the retainer ring, 843004.

Note! Never compress the retainer ring more than necessary toremove it from the groove.

14 Drive out the gudgeon pin from the opposite side. In lowtemperatures the gudgeon pin may stick but will be easilyremoved after heating the piston to about 30°C, e.g. in oil.

15 If the rings and grooves require cleaning, measuringetc., remove the piston rings by using the pliers 843003.Before removing, note the position of the rings to ensuremounting in the same grooves. The design of the pliers pre-vents overstressing of the rings. Using other means may over-stress the rings.

11.4.4 Maintenance of piston, piston rings and con-necting rod bearings

1 Clean all the parts carefully. Remove the piston rings,and remove burned carbon deposits from the piston and pistonring grooves. Special care should be taken not to damage thepiston material.

Never use emery cloth on the piston skirt.

The cleaning is facilitated if coked parts are soaked in keroseneor fuel oil. An efficient carbon solvent — e.g. ARDROX No. 668 orsimilar — should preferably be used to facilitate cleaning of thepiston crown. When using chemical cleaning agents, take care notto clean piston skirt with such agents because the phos-phate/graphite overlay may be damaged.

2 Measure the height of the piston ring grooves.

3 Dismantle composite piston for inspection of mating sur-faces between piston skirt and piston crown. Inspect and cleanoil spaces. See tightening procedure mentioned in chapter07./ Piston.



When mounting a new cylinder liner, all rings are to be re-placed by new ones.After honing of a liner, all rings are to be replaced by new ones.

4 Check the gudgeon bearing bush and big end bearingbore . When measuring the big end bearing bore the connect-ing rod screws are to be tightened to the stated pressure. Wear of bimetal bearing shells can be settled by measuring thethickness. For this purpose a ball anvil micrometer should beused. The wear limits given in chapter 06.2 should be applied. When replacing a big end bearing both the upper and the lowerbearing shell should be renewed.

Mark new bearings with the bearing number.

11.4.5 Assembling and mounting of piston and connecting rod

1 Lubricate the gudgeon pin, and mount from the sameside from where it was removed, with the end marked with thedrawing number in the same direction. The cylinder numberis stamped on the piston crown and connecting rod. Whenchanging the piston, mark the new piston with the samecylinder number in the same place as on the replaced one. At low temperatures, the gudgeon pin may stick but will beeasily fitted after heating the piston to about 30°C, e.g. in oil.

2 Mount the retainer ring.

Note! Never compress the retainer ring more than necessary to fitinto the groove. If the ring is loose in its groove after mounting,it must be replaced by a new one.

3 Fasten the lifting tool 832002 to the piston crown .

4 Turn the crankshaft about 55° from the TDC towards theoperating side for the cylinder concerned, see Fig 11-5.

5 Mount the piston rings by using the pliers 843003. Ifrings are reused, take care not to turn them upside down.Before new rings are mounted, check the height of the ringgrooves. The height must not exceed the wear limit. The ringsshould be placed with gaps located 120° in relation to eachother. Note the mark “TOP” near the ring gap.

6 Lift the piston and connecting rod.



7 Lubricate the piston and place the clamp device for pistonrings, 843002, around the piston, checking that the pistonrings slide into their grooves.

8 Spread a thin oil film on the upper big end bearing shellrunning surface and on its back side. Both end faces to belubricated with grease or oil. Mount the bearing shell with thelug guiding in its groove into the connecting rod. Check thatthe shell is mounted straight.

Caution! Any use of glue on a bearing shell is prohibited.

9 Take off the protecting tape from the crank pin oil holesand lubricate the crank pin with clean engine oil.

10 Lower the piston/connecting rod carefully into the cyl-inder liner.

11 Lower the piston further until the connecting rod can beplaced on the crank pin.

12 Spread a thin oil film on the lower bearing shell runningsurface and on its back side. Both end faces to be lubricatedwith grease or oil. Mount the bearing shell with the lug guidingin its groove into the bearing cap. Check that the shell ismounted straight.

On a connecting rod screw with an end plug the condition ofthe plug should be checked before assembly.

Connecting rod screws

Caution! An end plug may under no circumstance be used with the270mm long connecting rod screw.

Plug

262

270

With plug

Without plug

Fig 11-6 2011810349



Check that no plug remains in the threaded holes of theconnecting rod before mounting the screws.

13 Lift the bearing cap in place and mount the upper screwtightening it by hand. Mount the nut. The serrations of thebearing cap/connecting rod and bearing shell ends must be inthe right relative position to each other. Tighten the nut byhand.

Check of the bearing shell alignment

14 Mount the lower screw and tighten both screws withthe tool 803011 to torque, see chapter 07 section 07.3. Screwon the lower nut and tighten it by hand.

Caution! Overtightenig of the screws will damage the plug at the endof the screws.

15 Lift the distance sleeves 861153 and the hydraulic tools,861159, together with extension pieces 861157, into position.Check again the alignment of the upper serration and bearingshell ends by hand before proceeding with tightening of con-necting rod nuts. There is no guiding pin for the upper serra-tion. It is recommended that the pressure is applied in two stepsaccording to description in chapter 07., section 07.3.4.Hydraulic oil

REASSEMBLING1. Screw on nuts, attach distance sleeve. Screw on cylinders by hand.2. Connect hoses, open valve. Tighten cylinders by hand.

3. Close the valve and pump pressure to the stated value.4. Screw the nuts until close contact to face.5. Open the valve and remove tool set.

Incorrect Correct

Fig 11-7 2011820349



Note! Check before and during the tightening that distance sleevesdo not touch the engine block.

Note! Check that the connecting rod is movable axially after tight-ening.

16 Check of the exposed section , that is valid only for theconnecting rod screws with end plug according to Fig 11-6. Thereference measurements are only for guidance to reveal thecondition of the end plug. If the length is out of limits, checkthe condition of the plug in the end of the connecting rod screw.

Connecting rod screw check

17 Mount the side covers.

18 Mount the anti-polishing ring.

19 Mount the cylinder head, see chapter 12 section 12.2.3

35.7+1.1-0.9

32.7+1.1-0.9

Fig 11-8 2011579446



Assambly Procedure for Connecting Rod Big End

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