Deck 11: Crankshaft, Bearings, and Engine Balancing

Question 1

Why do 90-degree V6 engines use soft engine mounts?

Answer 1

Ninety-degree V6 engines use soft engine mounts that allow the engine to move from side to side. This is an effective way of smoothing out engine vibrations for rear-wheel-drive vehicles.

Question 2

How do forged crankshafts compare to cast crankshafts in terms of strength and cost?

Answer 2

Forged crankshafts are stronger but more costly than cast crankshafts.

Question 3

How is dynamic imbalance corrected?

Answer 3

Dynamic imbalance is corrected by adding or removing metal at two different places on the crankshaft.

Question 4

All of the below are causes of thrust bearing failure, EXCEPT _____.

A)missing or poor electrical grounds
B)excessive torque convertor pressure
C)poor thrust bearing surface finish
D)a correctly installed rope seal

Question 5

Technician A says the rotating end of the connecting rod is the big end. Technician B says the reciprocating end of the connecting rod is the big end. Who is correct?

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

Question 6

Undersize bearings have a thinner bearing back.

Question 7

Cast nodular iron crankshafts require extra care in grinding.

Question 8

Damaging the tone ring on a crankshaft can result in computer problems.

Question 9

Technician A says excessive drive belt tension can cause wear on the upper, front main bearing. Technician B says maintaining proper oil clearance and a lower viscosity oil will increase the fatigue life of a bearing. Who is right?

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

Question 10

At the factory, what part does the reciprocating weight of the pistons and rods play?

Question 11

To clean minor rust from a crankshaft journal, use a 300-grit sandpaper.

Question 12

A copper-lead bearing can carry loads as high as _____ psi.

A)7,000
B)8,000
C)10,000
D)12,000

Question 13

Technician A says that bearing clearance can be reduced by as much as 40% with aluminum bearings. Technician B says excessive crush will allow a bearing to move back and forth in the bore. Who is correct?

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

Question 14

Engine balance is being discussed. Technician A says balance in an in-line engine is not as important as in a V-type engine. Technician B says some steel crankshafts must not be replaced with a cast crankshaft or balance problems may occur. Who is right?

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

Question 15

Technician A says a typical V8 can be balanced in about 30 minutes. Technician B says in-line engines do not use bob weights. Who is correct?

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

Question 16

What are engines called that are balanced with part of the counterweight on the flywheel or damper?

Question 17

Thrust bearings are being discussed. Technician A says the thrust bearing surface facing the front of the engine shows the most wear. Technician B says the most common cause of thrust bearing failure is too little clearance. Who is correct?

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

Question 18

Every other rod journal has a counterweight.

Question 19

Technician A says the outer ring of the vibration damper can slip out of position. Technician B says the most vibration occurs at the rear of the crankshaft. Who is right?

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

Question 20

Technician A says many balance shafts are supported by needle bearings. Technician B says as the piston approaches TDC, its force pulls the engine up. Who is correct?

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

Question 21

How much thicker than standard would a 0.020" undersized bearing insert be?

Question 22

When there is less clearance, will a Plastigage reading be wider or narrower?

Question 23

Normal main bearing wear is on the _____.
A. top B. bottom

Question 24

What is another name for the rod journal?

Question 25

What are three properties of a bearing?
A.
B.
C.

Question 26

What are the names of two types of hardening?
A.
B.

Question 27

Technician A says that bearings have a soft surface that flows away from high spots in case of a nick in the crankshaft. Technician B says that dirt can be absorbed into the crankshaft journal surface. Who is right?

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

Question 28

What part of the crankshaft can be rolled with a hydraulic roller to increase crankshaft strength?

Question 29

Technician A says that stretched connecting rods often need resizing when the bearing clearance at the bearing parting line becomes excessive. Technician B says that normal connecting bearing wear is on the cap end. Who is right?

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

Question 30

What is the name of the rounded area at the edge of each bearing journal?

Question 31

Which crankshaft is stronger, cast or forged?

Question 32

Name three types of scales used in engine balancing.
A.
B.
C.

Question 33

What is the term that describes the crankshaft being pushed forward by the clutch or torque converter?

Question 34

When a rod journal is tapered, what should be checked as a possible cause?

Question 35

List (in inches) the different undersizes to which a crankshaft can be reground.

Question 36

The hardness specification is usually given on the _____ "C" scale.

Question 37

What is the difference in appearance between an in-line engine rod journal and a V8 rod journal?

Question 38

Technician A says that normal main bearing wear is on the top. Technician B says that worn lower main bearings can be caused by lugging the engine. Who is right?

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

Question 39

An engine has a burned thrust main bearing. Technician A says that this can be caused by a driver who "rides" the clutch. Technician B says that this can be caused by insufficient clutch pedal-free travel. Who is right?

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

Question 40

A crankshaft has been ground to 0.010"-0.020". Technician A says that 0.010" traditionally represents the rod journal undersize. Technician B says that 0.020" represents the main bearing undersize. Who is right?

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

Question 41

Technician A says that cast crankshafts have larger counterweights than forged crankshafts. Technician B says that forged crankshafts are usually externally balanced with weights on the damper and torque converter. Who is right?

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

Question 42

Metal is being ground from the surface of a crankshaft. Technician A says that 0.010" of metal is removed from the surface of a 0.010" crankshaft. Technician B says that 0.015" of metal is removed from the surface of a 0.030" crankshaft. Who is right?

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

Question 43

Technician A says that many four cylinder engines do not use a damper. Technician B says that a loose or damaged damper can break the crankshaft. 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 spread is when the bearing insert extends above the parting surface. Technician B says that crush is what keeps the bearing from spinning in the bearing bore. Who is right?

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

Question 45

Technician A says that engine vibration problems can sometimes be resolved by installing the correct engine mounts. Technician B says that counterweights that are too light are drilled and filled with heavier metal. Who is right?

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