Deck 8: Engine Feedback Assembly

Question 1

Which of the following is NOT a diesel engine feedback assembly component?

A) timing gear train
B) camshaft
C) valve train
D) connecting rod

Answer 1

connecting rod

Question 2

A four-stroke cycle diesel engine has a crankshaft gear with 45 teeth. How many teeth should the camshaft gear have if it is direct-driven?

A) 22
B) 45
C) 90
D) 180

Answer 2

90

Question 3

Which type of engine timing gear tooth design has the advantage of low thrust loads?

A) spur
B) helical
C) amboid
D) hypoid

Answer 3

spur

Question 4

To what temperature should a camshaft gear usually be heated prior to installation on a camshaft?

A) 100 degrees Fahrenheit
B) 200 degrees Fahrenheit
C) 300 degrees Fahrenheit
D) 400 degrees Fahrenheit

Question 5

Technician A says that camshaft rotation must be in the same direction as crankshaft rotation. Technician B says that camshaft rotation may be opposite to crankshaft rotation. Who is right?

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

Question 6

Which of the following specifications for engine timing gear train backlash would be typical?

A) 100 mm
B) 200 mm
C) 400 mm
D) 800 mm

Question 7

Technician A says that a pre-2010 Cummins ISX uses a dual OHC design. Technician B says that a post-2010 Cummins ISX uses a single OHC design. Who is correct?

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

Question 8

Which of the following terms is used to describe the shortest radial dimension of a cam profile?

A) inner base circle
B) outer base circle
C) lift flank
D) unload flank

Question 9

Which of the following terms is used to describe the largest radial dimension of a cam profile?

A) inner base circle
B) outer base circle
C) lift flank
D) unload flank

Question 10

What should be used to check an out-of-engine camshaft for bend?

A) inside micrometer
B) outside micrometer
C) dial bore gauge
D) dial indicator and V-blocks

Question 11

The injector cam profile on a camshaft shows visible deterioration of the hard surfacing. What should be done?

A) polish with an emery cloth
B) machine smooth
C) replace camshaft
D) repair by metalizing

Question 12

Which of the following could be used to measure cam bushing bore in a cylinder block?

A) deck micrometer
B) outside micrometer
C) dial bore gauge
D) Plastigage^tm

Question 13

If a cam profile is described as being mostly outer base circle, what would be true of the train it actuates?

A) actuated twice per revolution
B) actuated every other revolution
C) loaded for most of the cycle
D) unloaded for most of the cycle

Question 14

Which of the following would provide the correct cam lift dimension?

A) OBC minus IBC
B) shaft centerline to toe dimension
C) IBC minus OBC
D) lift flank minus unload flank dimension

Question 15

Which of the following is NOT found in medium and heavy duty truck diesel engines?

A) cast iron solid lifters
B) middle alloy steel solid lifters
C) roller type cam followers
D) hydraulic lifters

Question 16

Which of the following is a required test for a push tube before returning it to service?

A) measure diameter with a micrometer
B) measure length with a shop ruler
C) roll on a true flat surface
D) magnetic flux test

Question 17

When a valve cam ramps from base circle to outer base circle, what is happening to the valve it actuates?

A) it is stationary
B) it is opening
C) it is closing
D) it is fully open

Question 18

Which of the following operates at the highest temperatures?

A) exhaust valves
B) intake valves
C) solid lifters
D) rockers

Question 19

When is valve float more likely to occur?

A) high engine speeds
B) low engine speeds
C) engine rated speeds
D) engine lugdown

Question 20

What is a major advantage of a valve rotator?

A) sharper interference angle may be used
B) reduce carbon buildup on seat
C) lower tension valve springs can be used
D) exhaust valves run cooler

Question 21

When testing valve spring tension, within what percentage of the original tension specification should the measurement be?

A) 5 percent
B) 10 percent
C) 15 percent
D) 20 percent

Question 22

Which of the following tools should be used to check the operation of an installed valve rotator?

A) light nylon hammer
B) dial bore gauge
C) outside micrometer
D) stethoscope

Question 23

When machine grinding valves, which of the following specifications requires close observation?

A) fillet
B) valve protrusion
C) valve recession
D) margin

Question 24

What part of a rocker contacts either the valve stem or valve bridge?

A) adjusting screw
B) boss
C) pallet
D) yoke

Question 25

What is the reason that OEMs specify greater valve lash for exhaust valves?

A) they run hotter and expand more
B) they run cooler and contract less
C) they are shorter than intake valves
D) they are longer than intake valves

Question 26

Valve setting specifications are provided by the OEM for performing overhead adjustment when engine temperature is:

A) at operating temperature
B) above 150 degrees Fahrenheit
C) 120 degrees Fahrenheit
D) below 100 degrees Fahrenheit

Question 27

On a typical in-line 6 cylinder, 4-stroke cycle diesel engine, when piston #5 is at TDC on it's compression stroke, which valves can be adjusted?

A) #5
B) #2
C) #4
D) #6

Question 28

In an in-line 6 cylinder, 4-stroke cycle diesel engine, what is the spacing between power strokes?

A) 60 degrees
B) 90 degrees
C) 120 degrees
D) 180 degrees

Question 29

Which of the following would provide higher valve seating force?

A) 30 degree cut valve
B) 45 degree cut valve
C) solid lifter valve trains
D) roller type cam followers

Question 30

What is the recommended tool used to check valve lash dimension?

A) thickness gauges
B) dial indicator
C) inside micrometer
D) snap gauge

Question 31

When performing a valve lash adjustment on a diesel engine, which of the following is recommended?

A) engine stationary and at operating temperature
B) engine running and at operating temperature
C) engine stationary and cold
D) engine running and cold

Question 32

What is commonly used to position a camshaft gear on a camshaft?

A) key and keyway
B) loctite
C) interference fit
D) staking

Question 33

What is the reason most manufacturers suggest that a valve bridge be removed from the engine before backing off the adjusting screw?

A) adjusting screw is easily damaged
B) bridge may be deformed
C) bridge guide is easily bent
D) rocker may be damaged

Question 34

If cylinder valves are set loose, which of the following performance-altering conditions will result?

A) advanced valve timing
B) hotter valve operating temperatures
C) noisier valve operation
D) retarded valve timing

Question 35

When a valve interference angle is used, which of the following would be a typical specification?

A) one degree
B) two degrees
C) five degrees
D) ten degrees

Question 36

When a camshaft has three profiles per engine cylinder, what is the center cam profile used for?

A) intake valve actuation
B) exhaust valve actuation
C) unit injector actuation
D) fuel pump actuation

Question 37

What is used to define camshaft endplay?

A) captured thrust springs
B) free thrust washers
C) either free or captured thrust washers
D) nothing

Question 38

What is the recommended method of measuring camshaft endplay?

A) dial indicator
B) depth micrometer
C) thickness gauges
D) calipers

Question 39

Which of the following is the odd one out?

A) tappets
B) lifters
C) push tubes
D) followers

Question 40

What is the rocker ratio of a rocker that converts 1 inch of cam lift into 1.5 inches of travel?

A) 1 : 3
B) 1 : 2
C) 1 : 1.5
D) 1 : 1

Question 41

What does the left side camshaft actuate in a pre-2010 Cummins ISX engine?

A) engine brake
B) exhaust valves
C) mechanical fuel injectors
D) intake valves

Question 42

What term is used to describe a gear that permits zero lash between intermeshing gears and also eliminates the risk of gears radially loading each other when at operating temperature?

A) concept gear
B) helical gear
C) amboid gear
D) spur gear

Question 43

When timing the overhead camshafts used on a pre-2010 Cummins ISX engine geartrain, which of the following tools must be used?

A) dial indicator
B) timing wedges
C) Plastigage^tm
D) calibration indices

Question 44

Technician A says that camshafts are used to convert linear motion into rotary force. Technician B says that a valve rocker can be considered to be part of the valve train actuated by cam profile. Who is correct?

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

Question 45

When a cylinder valve is manufactured with a stem and head of different alloys, what is commonly used to join each part?

A) threads
B) adhesive
C) hard-surfacing
D) inertial weld

Question 46

Which of the following is another way of describing valve keepers?

A) margins
B) split locks
C) fillet radius
D) headers

Question 47

How many keepers are required to retain one cylinder valve?

A) one
B) two
C) four
D) eight

Question 48

When variable valve timing (VVT) is used on a Caterpillar diesel engine, which of the following becomes variable?

A) valve overlap
B) valve lift dimension
C) moment of intake valve closure
D) moment of intake valve opening

Question 49

When variable valve timing (VVT) is used, what controls the VVT actuator?

A) manifold boost
B) engine rpm
C) ECM
D) exhaust back pressure

Question 50

Technician A says that a common cause of top end clatter in a diesel engine is loose set cylinder valves. Technician B says that loose set valves are subject to lower shock loads on opening and closing because they travel less distance. Who is correct?

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