Basics Automotive Repair Technician 2 : Engine

Automotive Repair Technician 2 : EngineBasics

Lesson 2 Overview

You’ll begin this phase of

your learning with an

introduction to both

gasoline and diesel engine

operation, including cooling

and lubrication systems

and intake and exhaust

systems. You'll explain

gasoline engine operation, parts, and specifications. Next, you'll

describe diesel fundamentals, advantages and disadvantages of

diesel power, diesel engine construction, and fuel ratios. Then, you'll

review the purpose, properties, and composition of engine coolant.

You'll learn about how to identify how an engine’s cooling system

operates and describe the role and importance of engine oil. Then,

you'll explain the process, operation, and diagnosis of hydrodynamic

lubrication in an automotive engine. You'll explain the purposes and

functions of the intake air and engine exhaust systems and their

Copyright Penn Foster, Inc. 2019 Course Version: 1

various components, including air filters, manifolds, and mufflers. And

finally, you'll identify how turbochargers and superchargers increase

the density of air and fuel charge to boost an engine’s horsepower.

2.1 Explain gasoline engine operation, parts, andspecificationsGasoline Engines

READING ASSIGNMENT

Read this assignment. Then read Chapter 18 in your textbook.

Gasoline Engine Operation, Parts, and Specifications

Chapter 18 explains how a gasoline-fueled engine operates, including

the four-stroke cycle of engine operation. In addition, you’ll learn the

characteristics used to classify engines, such as cylinder arrangement

(in-line, V-type, horizontally opposed), engine mounting, and camshaft

location (in-block or overhead). The text further describes how engine

displacement or size is established by explaining engine bore and

stroke and how they’re determined. Finally, you’ll learn about

compression ratio and how it’s calculated, along with what determines

engine horsepower and torque.

You need to understand how the four-stroke cycle of an internal

combustion engine works. Click here (jameshalderman.com/links/a1/ht

ml5/4_stroke_cycle.html) to view an animation of this cycle.

Most vehicles you’ll be working on will contain four-stroke engines.

Each of the four processes—(1) the intake stroke, (2) the compression

stroke, (3) the power stroke, and (4) the exhaust stroke—are


http://jameshalderman.com/links/a1/html5/4_stroke_cycle.html

illustrated in Figure 18-5 on page 150 of your textbook. As you read

the following details of these processes, you may find it helpful to refer

to the corresponding drawings on that page.

The intake stroke starts with the piston at top dead center (TDC). The

lobe on the camshaft then opens the intake valve. Crankshaft rotation

brings the piston down in the bore. Downward movement of the piston

creates a low-pressure area above the piston (as volume increases,

pressure decreases). Air rushes in to fill space left by the piston’s

downward movement because atmospheric pressure is greater than

the pressure in the cylinder. As the piston moves down, it pulls outside

air through the air cleaner, into the intake manifold, past the open

intake valve, and into the cylinder. The piston tries to inhale a volume

equal to its own displacement. During the intake stroke, air and fuel

are mixed and pulled into the cylinder in a specific ratio. The throttle

controls the air mass that enters the cylinder. Energy needed to move

the piston from TDC downward comes from either the flywheel or

overlapping power strokes. As the piston nears bottom dead center

(BDC), it slows down nearly to a stop. When the piston reaches BDC,

the intake valve closes, sealing the cylinder.

The compression stroke then begins. The turning crankshaft now

forces the piston upward. Both valves are closed; there’s no way for

air to get out except past the rings. According to Boyle’s law, pressure

is inversely proportional to volume, so as volume decreases in the

cylinder, the air-fuel mixture is compressed. In the compression of a

gas, volume decreases and pressure and temperature rise as external


work is done on the gas. The compression ratio is the ratio of volume

at BDC to the volume at TDC, or the clearance volume. A higher

compression ratio means higher thermal efficiency, or that portion of

heat supplied to the engine that’s turned into work.

The power stroke begins shortly after the fuel-air mixture is ignited by

a spark plug. The air-fuel mixture ignites in the combustion chamber

and the fuel burns, supported by oxygen. The high pressures in the

cylinder push down on the piston. This pressure forces the piston

down in the bore, which causes the crankshaft to rotate. Pressure falls

as volume increases. Temperature also falls as gas does external

work. The burning mixture expands and pushes the piston down

during the power stroke. As the piston continues downward, the

gasses in the cylinder expand and cool as they give up their energy.

The power stroke is the only stroke in which fuel energy is used and

cylinder pressure is at its highest.

As the piston nears the bottom of its travel, the exhaust valve begins

to open. The piston then begins to rise in the cylinder, triggering the

exhaust stroke. Upward movement of the piston forces spent gasses

past the exhaust valve and out of the cylinder. As the piston nears the

top of its movement, the camshaft lobe again opens the intake valve

and the cycle repeats. The exhaust valve is allowed to close by spring

pressure shortly after the piston begins its downward movement. The

exhaust stroke produces no work but expends a quantity of energy to

push exhaust gasses from the cylinder.


CALCULATING DISPLACEMENT

Turn to page 155 of your textbook and look at Chart 18-1. Choose one

displacement amount for each of the three types of engines. Then,

using the conversion formula on page 154 (liters = cubic inches ÷

61.02), calculate the liter values for each displacement and round to

the nearest tenth. Research for any engine manufacturers using an

engine of that size, and note what vehicles they’re used in. If you’re

not able to locate any engines with that displacement, change the

bore or stroke of the engine, calculate the revised displacement, and

search again.

Key Points and Link

READING ASSIGNMENT

Key Points

Most vehicles you’ll be working on will contain four-stroke

engines: the intake stroke, the compression stroke, the power

stroke, and the exhaust stroke.

A higher compression ratio means higher thermal efficiency, or

that portion of heat supplied to the engine that’s turned into work.

The power stroke is the only stroke in which fuel energy is used

and cylinder pressure is at its highest.

The exhaust stroke produces no work but expends a quantity of

energy to push exhaust gasses from the cylinder.

Link


Four-Stroke Cycle (jameshalderman.com/links/a1/html5/4_stroke_cycl

e.html)

Exercise: Gasoline Engines

Based on your reading, answer the following.

1. _______ rotations of the crankshaft are required to complete

each stroke of a four-stroke cycle engine.

2. A rotating force is called _______.

3. Technician A says that a crankshaft determines the stroke of an

engine. Technician B says that the length of the connecting rod

determines the stroke of an engine. Who is correct?

Exercise Answer Key:

Exercise: Gasoline Engines

1. One-half

2. torque

3. Technician A

2.2 Describe diesel fundamentals, advantages anddisadvantages of diesel power, diesel engineconstruction, and fuel ratios


http://jameshalderman.com/links/a1/html5/4_stroke_cycle.html

Diesel Engines

READING ASSIGNMENT


Diesel Engine Operation and Diagnosis

Chapter 19 explains diesel fundamentals, advantages and

disadvantages of diesel power, diesel engine construction, and fuel

ratios. This chapter also covers the diesel fuel system, starting with

how fuel is supplied to the engine. In addition, you’ll learn about the

different types of electronic fuel injection delivery systems and their

components. Pay particular attention to the difference between direct

and indirect injection and the three phases of diesel combustion.

The diesel glow-plug starting system is covered next. Following that

section, you’ll read about various types of exhaust emission control

devices, including exhaust gas recirculation (EGR), diesel particulate

filters (DPF), and selective catalyst reduction (SCR) converters. Diesel

exhaust smoke color can indicate whether or not an engine is healthy.

Knowing how to analyze it is an important skill for any auto repair

technician. Make sure to pay attention to the diesel exhaust smoke

diagnosis section on page 171 of your textbook. Lastly, you’ll read

about several types of diesel-engine testing.

To view the videos for this chapter, click here (www.jameshalderman.c

om/links/book_at/vid/ch19/video_frame.html) .

Click here (jameshalderman.com/links/a9/html5/diesel_4_stroke_cycle


http://www.jameshalderman.com/links/book_at/vid/ch19/video_frame.html

http://jameshalderman.com/links/a9/html5/diesel_4_stroke_cycle_2.html

_2.html) to view an animation of how a diesel engine works and how it

differs from a gasoline engine. Then read the text that describes the

animation.

The four-stroke diesel cycle is virtually the same as the four-stroke

gasoline engine you studied earlier. That being said, there are

differences in combustion, power control, and compression ratio. As in

the gasoline engine, the four-stroke diesel cycle consists of intake,

compression, power, and exhaust. Let’s look at the cycle now in more

detail.

During the intake stroke, the piston moves down, pulling outside air

through the air cleaner, into the manifold, past the open intake valve,

and into the cylinder. Downward movement of the piston creates a

low-pressure area above the piston. Air rushes in to fill the space left

by this downward movement, because atmospheric pressure is

greater than the pressure in the cylinder. Again, the piston tries to

inhale a volume equal to its own displacement. However, this fuel-air

mixture is not entirely pure. During the intake stroke, only air is

inducted. No throttle exists, so the cylinder is completely filled with air

at inlet manifold pressure. Air then mixes with any residual gases in

the cylinder. The energy needed to move the piston from TDC

downward comes from either flywheel or overlapping power strokes

on a multiple-cylinder engine. As the piston nears BDC, it slows down

nearly to a stop. When the piston reaches BDC, the intake valve

closes, sealing the air-filled cylinder.


Then the compression stroke begins. The turning crankshaft now

forces the piston upward. Both valves are closed; there’s no way for

air to get out except past the rings. Volume is decreasing as the piston

rises, so the air is compressed. This causes collisions of air molecules

within the cylinder. For example, if a volume of air is compressed to

1⁄16 of its original volume in a diesel engine, open space among the

molecules is reduced, increasing the number of molecule collisions

and the level of pressure among them. The kinetic energy of these

molecule collisions causes heat.

Remember that a higher compression ratio means higher thermal

efficiency, or that portion of heat supplied to the engine that’s turned

into work. As the compression ratio increases, the expansion ratio

decreases. Thus, thermal efficiency increases. Diesels have

compression ratios ranging from 16∶1 to 22∶1. High heat generated by

this greater compression will cause fuel when injected to atomize, or

break up, into finely divided particles, allowing the fuel to mix easily

with air. In an indirect injection (IDI) engine, mixing is further enhanced

when the spinning action of the spherical-shaped pre-chamber

produces additional heat. Ignition occurs as fuel mixes with air. (The

temperature of compressed air is about 1,000ºF. This temperature is

higher than the spontaneous ignition point of the fuel, which is

approximately 558ºF [292ºC].)

Near the end of the compression stroke, fuel sprays into either the

pre-chamber in an IDI engine or the combustion chamber in a direct


injected (DI) engine. The spherical shape of the IDI’s pre-combustion

chamber mixes air and fuel through the swirling of air, or this assists in

promoting high turbulence. Turbulence is the extreme disturbance of

compressed air; where air molecules to move in all directions, colliding

with each other and causing friction and heat. This increases heat

transfer between the cool liquid-fuel droplets and the hotter air. In a DI

engine, compressed air swirls in a Toroidal piston cavity, which means

that the shape is designed to increase friction between air molecules.

This also promotes the mixture of air and fuel as well as high

turbulence.

The power stroke begins shortly after the fuel injector sprays fuel into

the main combustion chamber or pre-chamber. The fuel begins to

vaporize and mix with hot compressed air. After about 0.001 second,

any air zones that are hot enough and contain the correct fuel-air ratio

ignite. It’s important to note that ignition will take place only where air

meets fuel. This ignition is called a diffusion flame.

First the fuel burns very rapidly, bringing about a sudden rise in

pressure. This causes an audible noise known as diesel knock. High

pressures in the cylinder push down on the piston. This pressure

forces the piston down in the bore, which causes the crankshaft to

rotate. Pressure falls as the volume increases. The combination of

oxygen and fuel burns and the remaining air expands, pushing the

piston down. As the piston continues downward, the gases in the

cylinder expand and cool, giving up their energy.


Now, as the piston nears the bottom of its travel, the exhaust valve

begins to open. The piston then begins to rise in the cylinder,

triggering the exhaust stroke. Upward movement of the piston forces

spent gases past the exhaust valve and out of the cylinder. As the

piston nears the top of its movement, the camshaft lobe again opens

the intake valve and the cycle repeats itself. The exhaust valve is

allowed to close by spring pressure shortly after the piston begins its

downward movement. Again, the exhaust stroke produces no work but

expends a quantity of energy to push exhaust gases from the cylinder.

To enhance your understanding of diesel engine operation, you can

view additional animations via the following links:

Diesel High Pressure Common Rail (www.jameshalderman.com/li

nks/a9/html5/diesel_hi_press_common_rail.html)

Fuel Injector, Electronic-Control (www.jameshalderman.com/links

/a9/html5/fuel-inject_elec_cntrl.html)

Electronic Fuel Injector (www.jameshalderman.com/links/a9/html

5/Electronic_Fuel_Injector.html)

Variable Vane Turbocharger (www.jameshalderman.com/links/a9

/html5/variable_vane_turbo.html)

Diesel Turbocharger and Intercooler Systems (www.jameshalder

man.com/links/a9/html5/Diesel_Turbocharger_and_Intercooler.ht

ml)

Diesel Particulate Filter (www.jameshalderman.com/links/a9/html

5/Diesel_Particulate_Filter.html)

Diesel Exhaust Fluid (www.jameshalderman.com/links/a9/html5/


http://www.jameshalderman.com/links/a9/html5/diesel_hi_press_common_rail.html

http://www.jameshalderman.com/links/a9/html5/fuel-inject_elec_cntrl.html

http://www.jameshalderman.com/links/a9/html5/Electronic_Fuel_Injector.html

http://www.jameshalderman.com/links/a9/html5/variable_vane_turbo.html

http://www.jameshalderman.com/links/a9/html5/Diesel_Turbocharger_and_Intercooler.html

http://www.jameshalderman.com/links/a9/html5/Diesel_Particulate_Filter.html

http://www.jameshalderman.com/links/a9/html5/Diesel_Exhaust_Fluid.html

Diesel_Exhaust_Fluid.html)

Key Points and Links

READING ASSIGNMENT

Key Points

During the intake stroke, the piston moves down, pulling outside air

through the air cleaner, into the manifold, past the open intake valve,

and into the cylinder.

A higher compression ratio means higher thermal efficiency, or that

portion of heat supplied to the engine that’s turned into work. As the

compression ratio increases, the expansion ratio decreases. Thus,

thermal efficiency increases.

Turbulence is the extreme disturbance of compressed air; where air

molecules to move in all directions, colliding with each other and

causing friction and heat.

Ignition will take place only where air meets fuel. This ignition is called

a diffusion flame.

Links

Chapter 19 Animations and Videos (www.jameshalderman.com/li

nks/book_at/vid/ch19/video_frame.html)

Four-Stroke Cycle (jameshalderman.com/links/a1/html5/diesel_4

_stroke_cycle.html)



http://jameshalderman.com/links/a1/html5/diesel_4_stroke_cycle.html

Diesel High Pressure Common Rail (www.jameshalderman.com/li

nks/a9/html5/diesel_hi_press_common_rail.html)

Fuel Injector, Electronic-Control (www.jameshalderman.com/links

/a9/html5/fuel-inject_elec_cntrl.html)

Electronic Fuel Injector (www.jameshalderman.com/links/a9/html

5/Electronic_Fuel_Injector.html)

Variable Vane Turbocharger (www.jameshalderman.com/links/a9

/html5/variable_vane_turbo.html)

Diesel Turbocharger and Intercooler Systems (www.jameshalder

man.com/links/a9/html5/Diesel_Turbocharger_and_Intercooler.ht

ml)

Diesel Particulate Filter (www.jameshalderman.com/links/a9/html

5/Diesel_Particulate_Filter.html)

Diesel Exhaust Fluid (www.jameshalderman.com/links/a9/html5/

Diesel_Exhaust_Fluid.html)

Exercise: Diesel Engines


1. _______ ignites diesel fuel in a warm diesel engine.

2. The _______ should be removed to test cylinder compression on

a diesel engine.


Exercise: Diesel Engines


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http://www.jameshalderman.com/links/a9/html5/fuel-inject_elec_cntrl.html

http://www.jameshalderman.com/links/a9/html5/Electronic_Fuel_Injector.html

http://www.jameshalderman.com/links/a9/html5/variable_vane_turbo.html

http://www.jameshalderman.com/links/a9/html5/Diesel_Turbocharger_and_Intercooler.html

http://www.jameshalderman.com/links/a9/html5/Diesel_Particulate_Filter.html

http://www.jameshalderman.com/links/a9/html5/Diesel_Exhaust_Fluid.html

1. Heat of compression

2. glow plug

2.3 Explain the purpose, properties, and composition ofengine coolantCoolant

READING ASSIGNMENT


Coolant Types

Chapter 20 explains the purpose, properties, and composition of

engine coolant. It also describes the various types of antifreeze

coolants. The most important information you’ll need to know from this

chapter includes how to store, recycle, test, and discard used coolant.

Take careful note when reading about environmental concerns and

replacement issues regarding coolant.

Engines use a 50/50 mixture of antifreeze and water to get the best

freeze protection while maintaining good heat transfer. This mixture

ratio is the best compromise between protection and performance.

Pure water freezes at 32°F (0°C), pure antifreeze (coolant) freezes at

0°F (–18°C), a 50/50 mix of water and coolant freezes at –34 °F (–

37°C), and a 70/30 antifreeze-water mixture freezes at –84°F (–

64°C). While the freezing temperature is lowest in the 70/30 mixture,


such a high concentration of coolant reduces its heat transferability.

For this reason, most manufacturers, like GM, Ford, Chrysler, and

Toyota, have traditionally specified a 50/50 mixture of antifreeze and

water to achieve the best balance between freeze protection and heat

conductivity. Recently, many OEMs like Honda and Toyota began

specifying the use of premixed coolants only. In this way, the water

quality can be maintained as well as the water/coolant ratio.

Coolant Testing

The following procedure will help you learn how to use a hydrometer

to measure coolant density, which indicates the ratio of coolant to

water in a mixture.

Note: The coolant hydrometer generally isn’t a precision measuring

instrument. In other words, you don’t need to try to get exact

temperature values.

Materials:

3 clear plastic cups with lids to prevent spills

1 coolant hydrometer (This can be purchased at an auto parts

store or online. The cost should be about $2.50.)

1⁄2 measuring cup

1⁄2 cup measuring cup

1 gallon pure antifreeze (This can also be purchased at an auto

parts store or online. The cost should be about $9.50.)


2 cups of water

Pencil and paper (to record your results)

An image of the materials needed for the procedure.

Materials Needed for the Procedure (Courtesy of Dr. John Kershaw)

An image of a hydrometer

reading for 100% coolant.

Hydrometer Reading for 100%

Coolant (Courtesy of Dr. John


Kershaw)


reading for 50/50 Water/Coolant

mixture.


reading for 70/30 Water/Coolant

mixture.

Hydrometer Reading for 50/50

Water/Coolant Mixture

(Courtesy of Dr. John Kershaw)


Hydrometer Reading for 70/30

Water/Coolant Mixture

(Courtesy of Dr. John Kershaw)

Procedure:

1. Assemble your materials.

2. Choose a safe working area away from pets or small children.

3. Label each cup as shown in Figure above.

4. Place 1 cup of pure coolant in the 100% container.

5. Place the hydrometer into the cup and draw a sample. Try to

keep the bubbles at a minimum.

6. Read the hydrometer and record the result.

7. Return the coolant to the cup and place a lid on it.

8. Using the 1⁄2 cup measuring cup, place 1⁄2 cup of water and 1⁄2

cup of coolant in the 50/50 container.

9. Using the hydrometer, measure and record the mixture’s freezing


point.

10. Return the mixture to the cup and place a lid on it.

11. Using the 1⁄3 cup measuring cup, place 2⁄3 cup of coolant and 1⁄3

cup of water in the 70/30 container.

12. Using the hydrometer, measure and record the mixture’s freezing

point.

13. Return the mixture to the cup and place a lid on it.

14. Clean up your materials by returning the coolant to the container

and storing it for future use.

The hydrometer shows the freezing point of the mixture, which

translates to freeze protection for the engine. As previously stated,

having the correct ratio is critical because it keeps components like

the radiator and engine block from freezing and overheating and, in

turn, needing repair or replacement.

SAFETY TIP: Never leave open coolant containers where animals

can reach them. Animals enjoy the sweet taste of coolant, but drinking

it can kill them. More information about this hazard can be found on

page 177 of your textbook.

To learn more about coolant, click here (jameshalderman.com/links/bo

ok_at/vid/ch20/video_frame.html) to watch this video.

ACID TECHNOLOGY


http://jameshalderman.com/links/book_at/vid/ch20/video_frame.html

Research to find out which coolants, besides DEX-COOL, are created

with organic-acid technology. Also, find out which states, other than

California and Oregon, require embittered coolant (coolant that isn’t

sweet to the tongue).

Key Points and Link

READING ASSIGNMENT

Key Points

Engines use a 50/50 mixture of antifreeze and water to get the best

freeze protection while maintaining good heat transfer.

Pure water freezes at 32°F (0°C), pure antifreeze (coolant) freezes at

0°F (–18°C), a 50/50 mix of water and coolant freezes at –34 °F (–

37°C), and a 70/30 antifreeze-water mixture freezes at –84°F (–

64°C).

Link

Chapter 20 Animations and Videos (jameshalderman.com/links/book_

at/vid/ch20/video_frame.html)

Exercise: Coolant


1. Coolant is water and _______.

2. As the percentage of antifreeze in the coolant increases, the


http://jameshalderman.com/links/book_at/vid/ch20/video_frame.html

_______.

3. A/an _______ mixture of water and coolant provides the best

combination of freezing protection and heat transfer ability in

coolant.

4. Some of the heavy metals found in used coolant include lead,

aluminum, and _______.


Exercise: Coolant

1. ethylene glycol

2. freeze point decreases (up to a point)

3. 50/50

4. iron

2.4 Identify how an engine’s cooling system operatesCooling System

READING ASSIGNMENT


Cooling System Operation and Diagnosis

Chapter 21 explains how an engine’s cooling system operates. In

particular, it shows how engine coolant flows through the engine, and

further explains the operation of the system’s major components:


Thermostat

Radiator

Pressure cap

Recovery system

Water pump

Cooling fans

Heater cores

The details of cooling-system testing, inspection, and service are also

described.

Cooling System Inspection

Accessory Drive Belt Tensioner

Many tensioners have marks that indicate the normal operating

tension range for the accessory drive belt. An example of this can be

found on page 195 in your textbook in Figure 21-31. If you have an

available car or light truck, check service information to find the

location of the tensioner marks. (You may find this information in the

owner’s manual or on the Internet.) Inspect the marks. Note the

relationship between the stationary mount and the tensioner and

whether they’re aligned as they should be.

Cooling System Hoses

Coolant system hoses are critical to engine cooling. As hoses get old,

they become either soft or brittle, or they sometimes swell in diameter.

Their condition depends on their material and engine service


conditions. If a hose breaks while the engine is running, all coolant will

be lost. Therefore, coolant hoses should be replaced any time they

appear to be abnormal. Inspect the cooling system hoses in your

vehicle, using Figure 21-34 on textbook page 196 as a visual guide.

See if something has chafed (rubbed) any of the hoses and

check for burn marks.

Feel the hoses to determine if they’re spongy and soft, hard,

swollen, or oil soaked.

If you find any of these conditions present in a hose it should be

replaced.

View additional cooling system videos and animations via the links

below:

Animations and Videos (www.jameshalderman.com/links/book_at

/vid/ch21/video_frame.html)

Changing Coolant (www.jameshalderman.com/links/a1/html5/coo

lant_replacement.html)

Cooling System Heat Storage (www.jameshalderman.com/links/a

1/html5/cooling_sys_heat_store_b.html)

Coolant Flow (www.jameshalderman.com/links/a1/html5/coolant_

flow_world_engine.html)


READING ASSIGNMENT

Key Points



http://www.jameshalderman.com/links/a1/html5/coolant_replacement.html

http://www.jameshalderman.com/links/a1/html5/cooling_sys_heat_store_b.html

http://www.jameshalderman.com/links/a1/html5/coolant_flow_world_engine.html

Key Points

The cooling system operation's major components are the thermostat,

radiator, pressure cap, recovery system, water pump, cooling fans,

and heater cores.

Coolant system hoses are critical to engine cooling.

See if something has chafed (rubbed) any of the hoses and check for

burn marks. Feel the hoses to determine if they’re spongy and soft,

hard, swollen, or oil soaked. If you find any of these conditions present

in a hose it should be replaced.

Links



Changing Coolant (www.jameshalderman.com/links/a1/html5/coo

lant_replacement.html)

Cooling System Heat Storage (www.jameshalderman.com/links/a

1/html5/cooling_sys_heat_store_b.html)

Coolant Flow (www.jameshalderman.com/links/a1/html5/coolant_

flow_world_engine.html)

Exercise: Cooling System Operation and Diagnosis


1. What is normal operating coolant temperature?



http://www.jameshalderman.com/links/a1/html5/coolant_replacement.html

http://www.jameshalderman.com/links/a1/html5/cooling_sys_heat_store_b.html

http://www.jameshalderman.com/links/a1/html5/coolant_flow_world_engine.html

2. Explain the flow of coolant through the engine and radiator.

3. Why is a cooling system pressurized?

4. What is the purpose of the coolant system bypass?

5. Describe how to perform a drain, flush, and refill procedure on a

cooling system.

6. Explain the operation of a thermostatic cooling fan.

7. Describe how to diagnose a heater problem.


Exercise: Cooling System Operation and Diagnosis

1. Most engines are equipped with a 195 thermostat and as a result,

will operate between 195 and 215 degrees, which is the opening

point and the fully open temperature of the thermostat.

2. The flow of coolant through the engine and radiator starts when

the thermostat opens. Coolant flows through the thermostat to

the upper radiator hose and then through the radiator. After the

coolant is cooled in the radiator, it is drawn into the water pump.

It is then forced out and through the block and cylinder head(s)

and then back to the thermostat.

3. The cooling system is pressurized because under pressure, the

coolant boiling temperature is increased.

4. The purpose of the bypass is to allow coolant flow through the

engine when the thermostat is closed.

5. To service a cooling system, the coolant should be drained, and

then a water hose or flushing machine is attached and allowed to


operate until all of the old coolant has been removed. New

coolant of the specified type is then added to achieve a 50/50

mixture of antifreeze and water.

6. A thermostatic cooling fan uses a silicone coupling between the

drive and the blades of the fan. When the temperature reaches a

predetermined point, the silicone expands into a chamber, locking

the drive to the fan blades.

7. To diagnose a heater problem, first feel the radiator hoses to see

that the coolant is hot enough. If the thermostat and coolant level

is okay, feel the temperature of the heater hoses; both should be

hot.

2.5 Describe the role and importance of engine oilEngine Oil

READING ASSIGNMENT


Engine Oil Types

Chapter 22 describes the role and importance of engine oil. You’ll

read about various oil specifications, including the different rating

systems, including:

Society of Automotive Engineers (SAE)

American Petroleum Institute (API)


International Lubricant Standardization and Approval Committee

(ILSAC)

European

Japanese

Your textbook also explains engine oil additives, synthetic oils,

vehicle-specific oil specifications, high mileage oils, and oil filters. In

addition, you’ll find a detailed, illustrated description of how to change

engine oil and the filter.

To view helpful videos for this chapter, click here (www.jameshalderm

an.com/links/book_at/vid/ch22/video_frame.html) .

The following statements are important additional facts, related to

Chapter 22, that you should know.

An internal combustion engine (ICE) lubrication system absorbs

one-third of the heat produced by an engine.

Oil ratings are constantly updated. Newer oil is backward

compatible, meaning it can be used in older vehicles.

Synthetic oils were first developed for the US Army Air Forces in

World War II to keep their high-performance turbocharged radial

aircraft engines alive. At the time, this couldn’t be done with

conventional oils.

Research to find out why there are different rating systems for engine

oil. Which one is used most often by OEMs?



Key Points and Link

READING ASSIGNMENT

Key Points

An internal combustion engine (ICE) lubrication system absorbs

one-third of the heat produced by an engine.

Oil ratings are constantly updated. Newer oil is backward

compatible, meaning it can be used in older vehicles.

Synthetic oils were first developed for the US Army Air Forces in

World War II to keep their high-performance turbocharged radial

aircraft engines alive. At the time, this couldn’t be done with

conventional oils.

Link



Exercise: Engine Oil


1. The W in SAE 5W-20 stands for the word _______.

2. Oil change intervals as specified by the vehicle manufacturer are

________ time and mileage intervals.

3. The SAE rating reflects the _______ of the oil.




Exercise: Engine Oil

1. "winter"

2. maximum

3. viscosity

2.6 Explain the process, operation, and diagnosis ofhydrodynamic lubrication in an automotive engineLubrication System

READING ASSIGNMENT


Lubrication System Operation and Diagnosis

Chapter 23 explains the process of hydrodynamic lubrication in an

automotive engine and describes how the different types of oil pumps

operate in the complete process of engine lubrication. The text

describes how oil flows to the valve train components. Oil pump

inspection, wear measurement, service, and dry sump systems are

also explained.

View additional lubrication system videos and animations via the links

below:





External Gear Oil Pump (www.jameshalderman.com/links/a1/html

5/ex_gear_oil_pump.html)

Gerotor Oil Pump Slow (www.jameshalderman.com/links/a1/html

5/gerotor_pump_slow.html)

Gerotor Oil Pump (www.jameshalderman.com/links/a1/html5/gero

tor_type_oil_pump.html)

Internal-External Gear Pump with Crescent (www.jameshalderma

n.com/links/a1/html5/internal_external_cresent.html)

Rotor-type Oil Pump (www.jameshalderman.com/links/a1/html5/r

otor_oil_pump.html)

Vane Phaser (Cam Retard) (www.jameshalderman.com/links/a1/

html5/vane_phaser.html)

Dry Sump Oil System (www.jameshalderman.com/links/a1/html5/

dry_sump_oil_system.html)

Oil Additives

Check in the vehicle owner’s manual before using oil additives. Some

manufacturers will void the engine warranty if unapproved additives

are found in the oil. When an engine fails, many new car and truck

dealers will perform an oil analysis to determine if the proper oil was

used.

CAVITATION

Research for the term cavitation. Try to find out what this does to the


http://www.jameshalderman.com/links/a1/html5/ex_gear_oil_pump.html

http://www.jameshalderman.com/links/a1/html5/gerotor_pump_slow.html

http://www.jameshalderman.com/links/a1/html5/gerotor_type_oil_pump.html

http://www.jameshalderman.com/links/a1/html5/internal_external_cresent.html

http://www.jameshalderman.com/links/a1/html5/rotor_oil_pump.html

http://www.jameshalderman.com/links/a1/html5/vane_phaser.html

http://www.jameshalderman.com/links/a1/html5/dry_sump_oil_system.html

cooling and lubrication system, the signs to look for, and the damage

caused by cavitation erosion. Then do an image search to view

examples.


READING ASSIGNMENT

Key Points

Check the vehicle owner’s manual before using oil additives.

Cavitation is the cooling and lubrication system (like bubbles or

voids).

Links



External Gear Oil Pump (www.jameshalderman.com/links/a1/html

5/ex_gear_oil_pump.html)

Gerotor Oil Pump Slow (www.jameshalderman.com/links/a1/html

5/gerotor_pump_slow.html)

Gerotor Oil Pump (www.jameshalderman.com/links/a1/html5/gero

tor_type_oil_pump.html)

Internal-External Gear Pump with Crescent (www.jameshalderma

n.com/links/a1/html5/internal_external_cresent.html)

Rotor-type Oil Pump (www.jameshalderman.com/links/a1/html5/r

otor_oil_pump.html)

Vane Phaser (Cam Retard) (www.jameshalderman.com/links/a1/



http://www.jameshalderman.com/links/a1/html5/ex_gear_oil_pump.html

http://www.jameshalderman.com/links/a1/html5/gerotor_pump_slow.html

http://www.jameshalderman.com/links/a1/html5/gerotor_type_oil_pump.html

http://www.jameshalderman.com/links/a1/html5/internal_external_cresent.html

http://www.jameshalderman.com/links/a1/html5/rotor_oil_pump.html

http://www.jameshalderman.com/links/a1/html5/vane_phaser.html

html5/vane_phaser.html)

Dry Sump Oil System (www.jameshalderman.com/links/a1/html5/

dry_sump_oil_system.html)

Exercise: Lubrication System


1. Oil clearance between main and rod bearings represents a

limited amount of _______ that the oil pump will normally handle

while still maintaining oil pressure.

2. The formation of an empty space within a solid object or body is

_______.


Exercise: Lubrication System

1. leakage

2. cavitation

2.7 Explain the purposes and functions of the intake airand engine exhaust systems and their variouscomponents, including air filters, manifolds, andmufflersIntake and Exhaust Systems


http://www.jameshalderman.com/links/a1/html5/dry_sump_oil_system.html

READING ASSIGNMENT


Intake and Exhaust

Chapter 24 explains the purposes and functions of the intake air and

engine exhaust systems and their various components, including air

filters, manifolds, and mufflers. This chapter also describes how an

internal combustion engine “breathes in” air and exhausts combustion

gases.

An image of a dirty air filter.

Dirty Air Filter (Courtesy of

James Halderman)

It’s very important to inspect the air filter and the air intake system

carefully during routine service. Debris or objects deposited by

animals can cause airflow restriction and reduce engine performance.

The "Dirty Ait Filter" image shows what an air filter looks like when it’s

time to be replaced.

Air-Filter Check


When completing an air-filter check on an available vehicle. You’ll

need a flashlight for this activity.

1. Following the instructions in the owner’s manual or online,

remove the vehicle’s air filter.

2. Shine the flashlight through the filter in all areas.

3. Study the passage of light through the filter. If the filter is still

passing air sufficiently, you should see light shining through the

filter material across the entire surface area. If light doesn’t seem

to pass through the filter, it needs to be changed.

View helpful videos showing maintenance of the intake and exhaust

systems by clicking here (www.jameshalderman.com/links/book_at/vid

/ch24/video_frame.html) .

The following statements are important additional facts, related to

Chapter 24, that you should know

Reusable air filters that are coated with an oil film can damage

some engine sensors and set off a diagnostic trouble code (DTC).

When this occurs, you need to follow the manufacturer’s

diagnostic process to remove the DTC.

Installing an aftermarket air intake without a resonance tube can

lead to an increase in induction noise.

Plastic manifolds are fragile, and following correct tightening

sequences and torque specifications is important.

EGR (exhaust gas recirculation) coolers are frequently used on

diesel engines.



Many “cold-air” intakes sold through performance companies can

actually draw in engine compartment heat if the air box is

replaced with an open filter element.

Key Points and Link

READING ASSIGNMENT

Key Points

It’s very important to inspect the air filter and the air intake system

carefully during routine service. Debris or objects deposited by

animals can cause airflow restriction and reduce engine

performance.

Reusable air filters that are coated with an oil film can damage

some engine sensors and set off a diagnostic trouble code (DTC).

When this occurs, you need to follow the manufacturer’s

diagnostic process to remove the DTC.

Installing an aftermarket air intake without a resonance tube can

lead to an increase in induction noise.

Plastic manifolds are fragile, and following correct tightening

sequences and torque specifications is important.

EGR (exhaust gas recirculation) coolers are frequently used on

diesel engines.

Many “cold-air” intakes sold through performance companies can

actually draw in engine compartment heat if the air box is

replaced with an open filter element.

Link


Chapter 24 Animations and Videos (www.jameshalderman.com/links/b

ook_at/vid/ch24/video_frame.html)

Exercise: Intake and Exhaust Systems


1. Technician A says that a stuck-open wastegate can cause the

engine to burn oil. Technician B says that a clogged positive

crankcase ventilation (PCV) system can cause the engine to burn

oil. Who is correct?

2. A/an _______ quiets the exhaust by smoothing out the high-

pressure exhaust pulses and allowing them to be released at an

even and constant rate.


Exercise: Intake and Exhaust Systems

1. Technician B

2. muffler

2.8 Identify how turbochargers and superchargersincrease the density of air and fuel charge to boost anengine’s horsepower



An Engine's Horsepower

READING ASSIGNMENT


Turbocharging and Supercharging

Chapter 25 discusses how turbochargers and superchargers increase

the density of air and fuel charge to boost an engine’s horsepower.

The difference between a turbocharger and a supercharger is

explained, along with how boost levels are controlled. This chapter

also describes maintenance procedures for these devices.

Air Density

In this exercise, you’ll find the air density of an inflated balloon, which

is higher than the density of the air around you.

Density = mass (weight) ÷ volume

A higher density of air-fuel mixture in a cylinder means a stronger

charge will be produced when it’s ignited, which leads to a higher-

powered engine.

Materials:

1 bucket, large enough to fully immerse an inflated balloon

1 bucket, large enough to hold the other bucket

1 balloon

1 small scale that reads in grams (such as one used to weigh

letters)


1 measuring cup that reads in liters or cm3

Water

1 towel

1 pin

Procedure:

1. Gather your materials and find a suitable location to work.

2. Place the smaller bucket inside the larger bucket. Fill the smaller

bucket to the brim with water. Be sure to keep any water from

spilling over. If it does, empty the larger bucket before continuing.

3. Inflate the balloon, tie it off, and immerse it in the smaller bucket

until it’s beneath the water’s surface entirely, causing water to

overflow into the larger bucket. Try to keep your hands out of the

water as much as possible.

4. Remove the balloon and set it aside to dry.

5. Remove the smaller bucket, being careful not to spill any

additional water into the larger one.

6. Pour the water from the larger bucket into the measuring cup.

Record how much water you added. This is the volume of the

balloon.

7. Dry the balloon with the towel.

8. Measure the weight of the inflated balloon on the scale. Record

your results.

9. Use the pin to put a hole in the balloon near the neck. This will

cause it to deflate.

10. Measure the weight of the empty balloon on the scale. Record


your results.

11. Subtract the weight of the deflated balloon from the weight of the

inflated balloon. Record your results.

12. Now divide the weight of the air found in step 10 by the volume of

the balloon found in step 6. The result of this calculation is the

density of the air in the balloon. Record your result.

Conclusion:

To compare your results with the density of air outside of the balloon,

click here (www.denysschen.com/denysschen/catalogue/density.aspx)

.

If you calculated correctly, you should have obtained a result that’s

greater than the one calculated there.

Click on the links below to view videos and animations on

turbochargers and superchargers:



Turbocharger (www.jameshalderman.com/links/a1/html5/turboch

arger%20operation.html)

Turbocharger Wastegate (www.jameshalderman.com/links/a1/ht

ml5/turbocharger_wastegate.html)

A supercharger was optional equipment on 1957 Fords. Some muscle

cars used Ram Air scoops to achieve a supercharging effect by


http://www.denysschen.com/denysschen/catalogue/density.aspx


http://www.jameshalderman.com/links/a1/html5/turbocharger operation.html

http://www.jameshalderman.com/links/a1/html5/turbocharger_wastegate.html

capturing high-pressure outside air.


READING ASSIGNMENT

Key Points

Turbochargers and superchargers increase the density of air and

fuel charge to boost an engine’s horsepower.

Some muscle cars used Ram Air scoops to achieve a

supercharging effect by capturing high-pressure outside air.

Links



Turbocharger (www.jameshalderman.com/links/a1/html5/turboch

arger%20operation.html)

Turbocharger Wastegate (www.jameshalderman.com/links/a1/ht

ml5/turbocharger_wastegate.html)

Exercise: An Engine's Horsepower


1. Two technicians are discussing the term turbo lag. Technician A

says that it refers to the delay between exhaust leaving the

cylinder and contacting the turbine blades of the turbocharger.



http://www.jameshalderman.com/links/a1/html5/turbocharger operation.html

http://www.jameshalderman.com/links/a1/html5/turbocharger_wastegate.html

Technician B says that it refers to the delay in boost pressure that

occurs when the throttle is first opened. Who is correct?

2. The most important service operation on an engine with a

turbocharger is _______.


Exercise: An Engine's Horsepower

1. Technician B only

2. regular oil changes

Lesson 2 Review

Self-Check

1. The four process of a four-stroke engine are the intake stroke,

compression stroke, power stroke, and

a. low-pressure stroke.

b. crankshaft stroke.

c. exhaust stroke.

d. piston stroke.

2. Which stroke of a four-stroke engine involves the turning crankshaft

forcing the piston upward?

a. Power

b. Compression stroke


c. Exhaust stroke

d. Intake stroke

3. In a four-stroke engine, the piston rises in the cylinder, which

triggers the _______ stroke.

a. intake

b. compression

c. power

d. exhaust

4. In the power stroke phase of a diesel engine, when air meets fuel

ignition happens. What is this ignition called?

a. Turbulence flame

b. Diffusion flame

c. Cylinder flame

d. Combustion flame

5. When diesel fuel burns rapidly and a sudden rise in pressure

happens, this causes a

a. diffusion flame.

b. piston rotation.

c. diesel knock.

d. pressure explosion.

6. Engines use a _______ mixture of antifreeze and water to get the

best freeze protection while maintaining good heat transfer.

a. 50/50

b. 60/40

c. 30/70

d. 10/90


7. Organic acid technology (OAT) coolant contains ethylene glycol, but

does not contain what?

a. Nitrates

b. Glysantin

c. Borates

d. Silicates or phosphates

8. Which two types of coolant are considered pet friendly?

a. Hybrid organic acid technology (HOAT) and propylene glycol

(PG).

b. Propylene glycol (PG) and ethylene glycol.

c. Propylene glycol (PG) and embittered coolant.

d. Embittered coolant and ethylene glycol.

9. How often should coolant hoses be replaced?

a. Whenever they appear abnormal.

b. Every five years.

c. Every six months.

d. They never need to be replaced.

10. What do most manufacturers offer as an option to help reduce cold

engine problems and to start engines in cold climates?

a. Water jackets

b. Plungers

c. Detonators

d. Block heaters

11. What is the name of the temperature-controlled valve placed at the

engine coolant outlet on most engines?

a. Thermostat


b. Heater core

c. Pressure cap

d. Water pump

12. What is engine oil's pour point?

a. The lowest temperature at which oil will pour

b. The viscosity range in which the oil fits

c. Its ability to mix with other oils

d. The highest temperature at which oil will pour

13. Oils tested at 0 degrees F are rated with a number and

a. the letter S, which indicates SAE.

b. the letter V, which indicates viscosity.

c. the letter W, which indicates winter.

d. the letter M, which indicates multigrade.

14. You are adding oil to an engine. You know that according to most

vehicle manufacturers, you should use SAE 5W-30 or what?

a. SAE 20W-30

b. SAE 5W-50

c. SAE 10W-30

d. SAE 100W-30

15. What is it called when oil leaks out between the shaft and the

bearing and is thick enough to allow contact to occur?

a. Molecular diffusion

b. Hydrodynamic viscosity

c. Boundary lubrication

d. Piston lubrication

16. All oil pumps are called


a. positive displacement pumps.

b. Inlet pumps.

c. Outlet pumps.

d. rotation pumps.

17. What is the most common type of air filter?

a. Plastic

b. Paper

c. Mesh

d. Steel

18. What does an EGR valve do?

a. Opens at speeds below idle on a cold engine.

b. Opens at speeds above idle on a cold engine.

c. Opens at speeds below idle on a warm engine.

d. Opens at speeds above idle on a warm engine.

19. What does volumetric efficiency measure?

a. How hot an engine gets.

b. How efficient an engine is.

c. How well an engine breathes.

d. The speed at which the valves in an engine open.

20. You are repairing an engine-driven air pump that supplies more

than the normal amount of air into the intake manifold, boosting

engine torque and power. What type of pump is this?

a. Roots

b. Supercharger

c. Torque

d. Bypass valve


Self-Check Answer Key

1. exhaust stroke.

Explanation: Most vehicles you’ll be working on will contain four-

stroke engines. The four processes are: (1) the intake stroke, (2)

the compression stroke, (3) the power stroke, and (4) the exhaust

stroke.

Reference: Section 2.1

2. Compression stroke

Explanation: When the compression stroke then begins, the

turning crankshaft forces the piston upward. Both valves are

closed, and there is no way for air to get out except past the

rings.


3. exhaust

Explanation: The exhaust stroke is trigger s the piston nears the

bottom of its travel, and the exhaust valve begins to open. The

piston then begins to rise in the cylinder.


4. Diffusion flame

Explanation: In a diesel power stroke phase, fuel begins to

vaporize and mix with hot compressed air. It is important to note


that ignition will take place only where air meets fuel. This ignition

is called a diffusion flame.


5. diesel knock.

Explanation: In a diesel engine, during the power stroke, the fuel

burns very rapidly, bringing about a sudden rise in pressure. This

causes an audible noise known as diesel knock.


6. 50/50

Explanation: Engines use a 50/50 mixture of antifreeze and water

to get the best freeze protection, while still maintaining good heat

transfer. This ratio is the best compromise between protection

and performance.


7. Silicates or phosphates

Explanation: Organic acid technology (OAT) coolant contains

ethylene glycol, but it does not contain silicates or phosphates.

This coolant is usually orange in color.


8. Propylene glycol (PG) and embittered coolant.

Explanation: Conventional ethylene glycol antifreeze has a sweet

taste, which makes it attractive to animals, including


pets. Propylene glycol (PG) and embittered coolant are

considered more pet-friendly alternatives.


9. Whenever they appear abnormal.

Explanation: As coolant hoses age, they become either soft or

brittle, or they sometimes swell in diameter. If a hose breaks while

the engine is running, all coolant will be lost, so coolant hoses

should be replaced any time they appear to be abnormal.


10. Block heaters

Explanation: Block heaters are often offered by manufacturers to

help combat cold engine problems, and to help engines start in

cold climates. They are plugged into household current, and the

heating element warms the coolant.


11. Thermostat

Explanation: A thermostat is the temperature-controlled valve that

is placed at the engine coolant outlet in most engines. Its purpose

is to control the minimum normal temperature of the engine.


12. The lowest temperature at which oil will pour

Explanation: Oil should not be too thick at low temperatures, to


allow the engine to start. The oil's pour point is the lowest

temperature at which oil will pour.


13. the letter W, which indicates winter.

Explanation: Oils tested at 0 degrees are rated with a number

and the letter W, indicating winter. It indicates the viscosity was

tested at 0 degrees. An example would be SAE 20W.


14. SAE 10W-30

Explanation: Most vehicle manufacturers recommend using SAE

5W-3- or SAE 10W-30. The recommendation is sometimes visibly

printed on the engine oil filler cap.


15. Boundary lubrication

Explanation: Boundary lubrication occurs when oil leaks out

around the oil clearance between the shaft and the bearing and

causes contact.


16. positive displacement pumps.

Explanation: All oil pumps are called positive displacement

pumps. Each pump rotation delivers the same amount of oil.

Everything that enters the pump must also exit it.



17. Paper

Explanation: Paper air filters are the most common type. The

paper is chemically treated, and it contains tiny passages in the

fibers, which form an indirect path for the flow of air to follow.


18. Opens at speeds above idle on a warm engine.

Explanation: Exhaust gas recirculation (EGR) valves are on some

cars in order to reduce emission of oxides of nitrogen. An EGR

valve opens at speeds above idle on a warm engine, in order to

allow a small portion of the exhaust gas enter the intake manifold.


19. How well an engine breathes.

Explanation: Volumetric efficiency is a measure of how well an

engine breathes. It is the comparison of the actual volume of air-

fuel mixture drawn into an engine to the theoretical maximum

value that could be drawn in.


20. Supercharger

Explanation: A supercharter is an engine-driven air pump that

supplies more than the normal amount of air into the intake

manifold, boosting engine torque and power. It provides an


instant increase in power, with no delay.


Flash Cards

1. Term: Intake Stroke

Definition: The first stroke of a four-stroke engine; starts with piston

at top dead center (TDC).

2. Term: Compression Stroke

Definition: The second stroke of a four-stroke engine; the turning

crankshaft forces the piston upward.

3. Term: Power Stroke

Definition: The third stroke of a four-stroke engine; the air-fuel

mixture ignites in the combustion chamber and the fuel burns,

supported by oxygen

4. Term: Exhaust Stroke

Definition: The fourth stroke of a four-stroke engine; upward

movement of the piston forces spent gases past the exhaust valve

and out of the cylinder

5. Term: Compression Ratio

Definition: The ratio of volume at BDC to volume at TDC, or the

clearance volume


6. Term: Direct Injection (DI)

Definition: A diesel engine in which fuel is injected directly into the

cylinder

7. Term: Indirect Injection (IDI)

Definition: A diesel engine in which fuel is injected into a small

prechamber, which is connected to the cylinder by a narrow opening

8. Term: Inorganic Additive Technology (IAT)

Definition: Conventional coolant that has been used for over 50 years

9. Term: Ethylene Glycol Based Coolant

Definition: Type of coolant recommended by all manufacturers, which

contains 47% ethylene glycol, 50% water, and 3% additives

10. Term: Coolant Recovery System

Definition: When a system cools, pressure in the cooling system is

reduced and a vacuum forms, which then pulls the coolant from the

plastic container back into the cooling system, keeping it cool.

11. Term: Reverse Cooling

Definition: A system used by some engines in which the coolant

flows from the radiator to the cylinder head(s) before flowing to the

engine block.


12. Term: Pour Point

Definition: Lowest temperature at which an oil will pour.

13. Term: Viscosity Index (VI)

Definition: Change in viscosity between cold and hot extremes

14. Term: Miscible

Definition: A trait of oil that allows it to mix with other oils without

causing problems, such as sludge.

15. Term: Boundary Lubrication

Definition: Oil leaks out around the oil clearance between the shaft

and the bearing and is thick enough to keep surfaces from seizing, but

allows contact to occur

16. Term: Hydrodynamic Lubrication

Definition: When a wedge-shaped oil film is built up between the

moving block and the surface

17. Term: Exhaust Gas Recirculation (EGR)

Definition: Type of valve in some engines, used to reduce the

emission of oxides in nitrogen; used from 1973 until recently on almost

all vehicles

18. Term: Micron

Definition: A unit of measurement equal to 0.000039 inch.


19. Term: Turbocharger

Definition: Uses the heat of the exhaust to power a turbine wheel and

does not directly reduce engine power

20. Term: Supercharger

Definition: An engine-driven air pump that supplies more than the

normal amount of air into the intake manifold and boosts engine

torque and power


Basics Automotive Repair Technician 2 : Engine

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Transcript of Basics Automotive Repair Technician 2 : Engine