Deck 3: Diagnosing Engine Problems

Question 1

A rich air-fuel mixture could cause a catalytic converter to overheat and melt.

Answer 1

True

Question 2

Technician A says if you remove the PCV valve from the valve cover and plug the end with your finger, the idle will increase if the valve is good. Technician B says that when you block the flow to the PCV valve, it will richen the air-fuel mixture. Which technician is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Answer 2

B

Question 3

List several causes of engine overheating.

Answer 3

Overheating can be caused by a water pump with a loose or corroded impeller. Check the pump flow by holding the top radiator hose with the engine running and the thermostat open at normal operating temperature. The surge of the coolant can be felt when the engine is accelerated. Besides obvious cooling system problems, overheating can be caused by retarded ignition timing, a partially blocked catalytic converter or exhaust system, or even by detonation due to an inoperative EGR valve.

Question 4

Oil leaks are being discussed. Technician A says a blue lamp can be used to locate an oil leak after a dye has been installed in the crankcase. Technician B says it is a black light that is used. Which technician is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 5

When does preignition occur?

Question 6

Highway driving can result in extra fuel and water dilution in the oil.

Question 7

Oil consumption problems are being discussed. Technician A says a lack of regular services can cause the oil control rings to plug. Technician B says worn compression rings can cause oil consumption problems. Who is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 8

Engine operation is being discussed. Technician A says preignition can cause engine damage. Technician B says carbon deposits on the pistons can increase the compression ratio. Who is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 9

Technician A says carbon removal additives can damage the muffler. Technician B says if the rpm rises when shorting a cylinder out, it could indicate a vacuum leak. Which technician is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 10

Technician A says grounding out a plug wire to a cylinder with a cracked piston will can increase the noise. Technician B says a rod knock will become quieter as its cylinder is grounded. Who is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 11

An infrared analyzer can be used to check the radiator for combustion leaks.

Question 12

During a compression test, a cylinder shows lower readings than expected. Technician A squirts a tablespoon of oil into the cylinder and the compression raises. He says this indicates a problem with the rings. Technician B says a running compression test should be about one-quarter of that of a cranking compression test. Which technician is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 13

Technician A says an indication of preignition could be a hole burned in the center of a piston. Technician B says detonation is an explosion inside the cylinder. Which technician is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 14

Technician A says that an air-fuel mixture that is too lean can cause burned internal engine parts. Technician B says an overly rich mixture can cause oil wash from cylinder walls. Which technician is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 15

Comparing premium fuel to regular fuel, the burn time of premium fuel is _____.

A)significantly shorter
B)only slightly shorter
C)longer
D)nearly the same

Question 16

If an engine will not turn over in either direction, it could be due to a broken crankshaft.

Question 17

An engine exhibits a low, steady vacuum reading. This could indicate _____.

A)a stuck valve
B)an improper ignition timing
C)plugged exhaust
D)bad compression rings

Question 18

Excessive clearance at a connecting rod bearing journal will cause a rod knock.

Question 19

Technician A says a faulty head gasket can cause the oil to mix with coolant. Technician B says this is called cross fluid contamination. Which technician is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 20

Technician A says that valvetrain noise will occur at half the speed of engine rpm. Technician B says valvetrain noises coming from inside the timing cover can be caused by a bad timing chain or chain guide. Which technician is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 21

When an engine runs for a long period with an excessively lean air-fuel mixture, what kind of engine damage can result?

Question 22

Carbon has built up in the neck area of a valve. What is the most probable cause?

Question 23

When engine idle rises during a cylinder power balance test, what could be the cause?

Question 24

Vacuum readings will drop approximately 1 inch for each _____ feet above sea level.

Question 25

What two different problems can be pinpointed by looking at the tops of the two pistons shown in Figure here?
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Question 26

Two technicians are discussing compression test results. Technician A says that abnormally low compression in adjacent (neighboring) cylinders most likely indicates a bad head gasket. Technician B says that if the reading on the compression tester goes up after adding oil to the cylinder, the compression rings are probably worn. Who is right?

A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B

Question 27

Technician A says that with a vacuum leak, an engine with an oxygen sensor feedback fuel system can run fine when cold but rough when hot. Technician B says that advanced ignition timing will often cause an engine to run hot. Who is right?

A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B

Question 28

If a spark plug is oil-fouled with carbon on only one side, what could be the cause?

Question 29

An engine has late valve timing. Technician A says that this will cause poor low rpm performance. Technician B says that at higher rpm, engine performance might be acceptable. Who is right?

A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B

Question 30

A noise goes away when the spark plug wire for one cylinder is disabled. What could this noise be?

Question 31

What other engine part failure sometimes results in a cracked piston?

Question 32

A roar will be heard through the engine's air intake when the _____ system is restricted.

Question 33

Technician A says that vacuum readings for an engine with a performance camshaft might be lower at idle. Technician B says that an engine that has worn lower main bearings will have lower oil pressure at freeway speeds. Who is right?

A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B

Question 34

An engine should produce a minimum of _____ inches of vacuum while cranking, but most engines will produce far more.

Question 35

When a spark plug is disabled and the noise becomes louder, what could this be?

Question 36

How many compression strokes (minimum) should the engine crank during a compression test?

Question 37

Technician A says that a compression test can be used to check the condition of the oil control rings. Technician B says that when several cylinders have low compression test readings, this can be due to burned or tight valves. Who is right?

A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B

Question 38

What happens to the outside of an exhaust pipe at the point of an internal restriction?

Question 39

During a compression test, remove all of the _____ _____ so the starter can crank the engine easily.

Question 40

At the end of a spark plug deposit test, what must be done before the engine is accelerated off idle?

Question 41

Technician A says that a cylinder leakage test is better than a compression test for testing the Condition of an engine before installing it in a car. Technician B says that a compression tester is better than a cylinder leakage tester for testing the condition of an engine with a performance camshaft. Who is right?

A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B

Question 42

A noise occurs at 1⁄2 crankshaft rpm. Technician A says that this could be a bad lifter. Technician B says that this could be a valve that needs to be adjusted. Who is right?

A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B

Question 43

An engine has a crack between a water jacket and an oil gallery. Technician A says that oil will go into the cooling system when the engine is running. Technician B says that coolant will go into the oil when the engine is off. Who is right?

A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B

Question 44

Technician A says that an engine that idles rough due to burned valves might run fine at speeds above idle. Technician B says that carbon buildup in a combustion chamber can cause an engine to have higher compression. Who is right?

A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B

Question 45

A car has oil smoke from its exhaust during deceleration. Technician A says that bad valve guide seals could be the cause. Technician B says that worn piston rings could be the cause. Who is right?

A)Technician A only
B)Technician B only
C)Both A and B
D)Neither A nor B