Deck 6: Cylinder Heads and Valve Train Mechanisms

Question 1

Which of the following reasons best explains why diesel engine cylinder heads use more head bolts per cylinder?

A)The engines are larger.
B)Diesel fuel burns at a hotter temperature.
C)Cylinder pressures are higher.
D)The stroke length is longer.

Answer 1

C

Question 2

The purpose of a variable intake swirl mechanism is to __________.

A)meter airflow into the cylinder
B)increase the exhaust temperature
C)reduce particulate emissions
D)reduce intake air noise

Answer 2

C

Question 3

Which of the following cylinder head valve train arrangements can provide the highest injection pressures?

A)Overhead camshaft.
B)L-head.
C)Overhead valves.
D)Roller type.

Answer 3

A

Question 4

Excessively worn valve train components are more commonly found on which valve actuation mechanism?

A)Intake valves.
B)Exhaust valves.
C)Engine brakes.
D)Rocker levers.

Question 5

The most common valve angle for poppet valves is ______.

A)45°
B)30°
C)20°
D)60°

Question 6

While examining a valve spring from an engine that is being overhauled, technician A says that valve springs should be checked for free length and cracks. Technician B says the spring should be checked for compressed spring pressure, nicks, and straightness. Who is correct?

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

Question 7

When adjusting the valve clearances on the engine, technician A says the valves are closed when the valve lifter or follower is on the inner base circle of the camshaft lobe. Technician B says that valves are always adjusted when closed while the lifter or follower is on the camshaft lobe outer base circle. Who is correct?

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

Question 8

Technician A says that before reusing any head bolt, it should be inspected for nicks and pitting. Technician B says the service manual should be consulted before reusing because some bolts can only be used once. Who is correct?

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

Question 9

While discussing variable valve timing in diesel engines, technician A says that only dual overhead camshafts (DOHCs) use variable valve timing. Technician B says variable valve timing is not commonly used in diesel engines. Who is correct?

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

Question 10

Valve overlap occurs during _____________.

A)the beginning of intake stroke and end of compression stroke
B)the beginning of intake stroke and end of exhaust stroke
C)the beginning of compression stroke and end of intake stroke
D)the beginning of intake stroke and end of power stroke

Question 11

A valve failure with a break between the head and stem was likely caused by _______.

A)a defective weld
B)excessive valve guide wear
C)contact between the valve and piston
D)an overheated valve

Question 12

Which valve guide in a turbocharged diesel engine will more likely not have valve stem seals?

A)Intake.
B)Exhaust.
C)Integral.
D)Replaceable.

Question 13

Technician A says that the cam gear rotates two times faster than the crank gear. Technician B says the cam gear rotates at half the engine speed. Who is correct?

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

Question 14

Technician A says that rear geartrains are used on engines because they operate with less noise. Technician B says that rear geartrains are used because they have less wear than a front geartrain mechanism. Who is correct?

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

Question 15

Technician A says that overhead cam engines with unit injectors can provide the greatest actuation force for the highest injection pressures. Technician B says that pushrod engines that use a low-mounted camshaft can provide the same force as an overhead camshaft engine to its unit injectors. Who is correct?

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

Question 16

The maximum allowable warpage for a cylinder head is approximately ___________.

A)0.004-0.006" (0.102-0.152 mm)
B)0.04-0.06" (1.02-1.52 mm)
C)0.001-0.005" (0.025-0.127 mm)
D)0.1-0.2" (2.5-5.1 mm)

Question 17

Which of the following is the most common method for achieving consistent head gasket clamping force on today's diesel engines?

A)Torquing bolts to a fixed value.
B)Using torque-yield head bolts
C)Using the torque-turn method.
D)Using MLS head gaskets.

Question 18

While installing a cylinder head, technician A says the threads in cylinder head bolts must be lubricated before installation. Technician B says that only the underside of the bolt head requires lubrication and that the threads only need be clean. Who is correct?

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

Question 19

Technician A says that fiber gaskets are the best and most commonly used gaskets in modern diesel engines. Technician B says that MLS gaskets are now the most commonly used head gaskets. Who is correct?

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

Question 20

Technician A says that whether combustion gases are leaking into the engine can be detected by measuring whether fuel hydrocarbons are present in the coolant. Technician B says that excessive gas pressure in the cooling system can indicate a head gasket leak. Who is correct?

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

Question 21

Lighter weight designs now have greater durability and lower maintenance requirements while improving:

A)exhaust emissions"
B)engine cooling"
C)fuel economy
D)cab heat"

Question 22

Aluminum's primary advantage is its:

A)tolerance of abrasive dirty oil"
B)greater electrochemical corrosion"
C)higher expansion rate
D)lightweight quality"

Question 23

What is produced from powdered iron alloys squeezed into molds at high pressures and then heated to bond the metal particles together?

A)Cast iron"
B)Steel"
C)Eco-Metal
D)Composite graphite iron (CGI)"

Question 24

What head design places the exhaust ports on the inboard side of the engine?

A)Cross-flow head"
B)Parallel flow head"
C)Reverse-flow head
D)Variable-swirl head"

Question 25

Technician A says to promote improved combustion at low speed and low engine loads, more turbulence is needed to better mix the intake air and fuel. Technician B says that the shape of the intake port is shaped so as to impart a twisting or spinning motion to the air as it enters the cylinder to increase turbulence. Who is right?

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

Question 26

A shorter, stiffer valve train permits unit injectors to be actuated to higher injection pressures of:

A)5,000 to 10,000 PSI
B)2525, 000 to 30, 000 PSI
C)40,000 to 45,000 PSI
D)45000 to 50 000 PSI"

Question 27

The purpose of a variable intake swirl mechanism is to __________.

A)meter airflow into the cylinder"
B)increase the exhaust temperature"
C)reduce particulate emissions
D)reduce intake air noise"

Question 28

What is the most common type of valve used in diesel engines?

A)Tappet"
B)Poppet"
C)Gate
D)Flow"

Question 29

An extra intake valve is used to:

A)decrease intake flow"
B)improve intake flow"
C)increase fuel economy
D)improve boost"

Question 30

Technician A says that integral valve guides cast into the cylinder head are removable. Technician B says that the condition of a valve guide is critical to oil consumption control. Who is right?

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

Question 31

What color is the diesel exhaust when the valve guides are worn?

A)White"
B)Black"
C)Blue
D)Gray"

Question 32

Technician A says that worn guides and missing valve stem seals lead to high oil consumption and blue smoke during acceleration. Technician B says that oil in the guides can carbonize, accelerating stem wear, and lead to more particulate emissions. Who is right?

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

Question 33

The condition where valves stay open, not returning to their seat, is known as:

A)valve float"
B)valve lift"
C)valve duration
D)valve overlap"

Question 34

The most common valve angle for poppet valves is ______.

A)45°"
B)30°"
C)20°
D)60°"

Question 35

What can be eliminated through the use of direct acting finger-type cam followers?

A)Rocker arms"
B)Valve bridge"
C)Valve seals
D)Pushrods"

Question 36

_____ is a comparison of the distance between the rocker shaft or fulcrum point of the rocker arm and the distance to each end of the rocker arm.

A)Rocker arm ratio"
B)Rocker arm length"
C)Valve bridge ratio
D)Valve bridge width"

Question 37

Technician A says that there are two varieties of crossheads: guideless nonadjustable and adjustable crossheads. Technician B says that crossheads are also called yokes or bridges. Who is right?

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

Question 38

Rocker arms are heat treated to resist:

A)wear"
B)rust"
C)corrosion
D)pitting"

Question 39

Which of the following transmits the cam actuation force from the followers to the rocker levers?

A)Roller cam"
B)Crosshead"
C)Pushrod
D)Bridge"

Question 40

Solid, short pushrods enable the use of higher injection pressures and reduced:

A)rocker arm ratio"
B)injection pressure"
C)injection lag
D)engine RPM"

Question 41

Two technicians are discussing pushrod service. Technician A says that if the weld at the ball socket end fractures, oil can enter and accumulate inside the pushrod. Technician B says the easiest way to check for oil entering the pushrod is to listen to the sound made when dropped. Who is right?

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

Question 42

Valve overlap occurs during _____________.

A)the beginning of intake stroke and end of compression stroke"
B)the beginning of intake stroke and end of exhaust stroke"
C)the beginning of compression stroke and end of intake stroke
D)the beginning of intake stroke and end of power stroke"

Question 43

Which valve guide in a turbocharged diesel engine will more likely not have valve stem seals?

A)Intake."
B)Exhaust."
C)Integral.
D)Replaceable."

Question 44

Technician A says that overhead cam engines with unit injectors can provide the greatest actuation force for the highest injection pressures. Technician B says that pushrod engines that use a low-mounted camshaft can provide the same force as an overhead camshaft engine to its unit injectors. Who is correct?

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

Question 45

Timing belts do not require lubrication but have a much shorter service interval, requiring replacement at approximately:

A)40,000 miles
B)50000 miles"
C)60,000 miles
D)100000 miles"

Question 46

Valve timing (opening and closing in relation to crank position) are controlled by the:

A)cam duration"
B)cam profile"
C)valve position
D)camshaft position sensor"

Question 47

Technician A says that overhead camshaft engines will often use two camshafts to optimally locate valves and ports on either side of the cylinder head. Technician B says that two camshafts eliminate the need for long rocker levers and rocker shafts. Who is right?

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

Question 48

In dual overhead cam engines, one of the two camshafts may actuate an intake and an exhaust valve in each half of the cylinder. What is this type of camshaft called?

A)Matched"
B)Reciprocal"
C)Paired
D)Linked"

Question 49

Very long periods of extended idle can lead to excessive formation of _____ on the back of the valve.

A)slobber"
B)soot"
C)carbon
D)lead"

Question 50

A valve adjustment is being discussed. Technician A says that you must first locate original equipment manufacturer (OEM) service literature for valve adjustment procedures. Technician B says that lash should be adjusted on a warm engine. Who is right?

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

Question 51

During a valve adjustment, cylinder 6, the companion of cylinder 1, should have two tight rocker levers at TDC for number 1 cylinder because both the valves should be open as the engine moves through the _______ position.

A)TDC overlap"
B)lift"
C)BDC overlap
D)lobe separation"

Question 52

When you rotate the engine 360 degrees in the correct direction of rotation until cylinder 6 is at TDC (end of compression stroke), cylinder 1 should be on:

A)TDC"
B)TDC overlap"
C)BDC
D)lobe separation"

Question 53

Most valves recede into the valve face and seat, often causing valve adjustments to:

A)loosen"
B)tighten up"
C)not change
D)become ineffective"

Question 54

Technician A says that continual pounding of the valve faces and seats can take place whenever valves are out of adjustment. Technician B says that maintenance of cylinder heads is often required when coolant or combustion leaks occur. Who is right?

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

Question 55

Care must be taken to inspect bolts for damage before reuse because all of the following, EXCEPT one, can lead to stress risers and breakage. Which one does not apply?

A)Nicks"
B)Corrosion"
C)Thread damage
D)Thread length"

Question 56

What ensures that more of the twisting force used to tighten a bolt turns the bolt and is not lost to friction on the bolt threads instead?

A)Proper torque"
B)Torque turn method"
C)Proper oiling
D)Proper bolt length"

Question 57

What are cylinder head bolts that have been tightened past their yield strength or elastic point called?

A)Torque to yield (TTY)"
B)High yield bolts"
C)Cap bolts
D)Three point metric bolts"

Question 58

Two technicians are explaining the torque turn method. Technician A says that this method requires initial bolt tightening with a torque wrench and then turning the bolt an additional number of degrees past this point. Technician B says that clamping forces with this method are the most consistent and widely preferred method. Who is right?

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

Question 59

Traditional copper and brass used in head gaskets were replaced by metal and asbestos gaskets during the:

A)1940s"
B)1950s"
C)1960s
D)1970s"

Question 60

Technician A says that some OEMs (original equipment manufacturers) require that diesel engine cylinder head bolts be loosened in a specified pattern. Technician B says that some cylinder head bolts must be discarded after use. Who is right?

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