Deck 11: Engine Cooling Systems

Question 1

When a diesel engine is operating at maximum efficiency, what percentage of the heat energy of the fuel is discharged as rejected heat?

A) 20 percent
B) 40 percent
C) 60 percent
D) 80 percent

Answer 1

60 percent

Question 2

How is rejected heat dissipated in a typical diesel engine?

A) 30 % to exhaust, 70 % to cooling system
B) 40 % to exhaust, 60 % to cooling system
C) 70 % to exhaust, 30 % to cooling system
D) 50 % to exhaust, 50 % to cooling system

Answer 2

50 % to exhaust, 50 % to cooling system

Question 3

When the heat of combustion is transmitted through a diesel engine cylinder block, the principle is known as:

A) conduction
B) convection
C) radiation
D) evaporation

Answer 3

conduction

Question 4

When heat is transferred by currents in fluids, the principle is known as:

A) conduction
B) convection
C) radiation
D) evaporation

Question 5

Where is the lowest pressure usually found in a diesel engine cooling system?

A) top radiator tank
B) bottom radiator tank
C) inlet to the water manifold
D) inlet to the water pump

Question 6

Which of the following components is not intended to function as a heat exchanger?

A) radiator
B) oil cooler
C) water manifold
D) air conditioning evaporator

Question 7

When water freezes, how much does it expand in volume?

A) 2 percent
B) 5 percent
C) 9 percent
D) 18 percent

Question 8

Which of the following coolants boasts the longest service life?

A) alcohol based coolant
B) EG
C) ELC
D) PG

Question 9

Which of the following does not conduct electricity ?

A) distilled water
B) EG
C) ELC
D) PG

Question 10

What mixture concentricity of ethylene glycol to water provides maximum antifreeze protection?

A) 100%
B) 60%
C) 30%
D) 20%

Question 11

What mixture concentricity of propylene glycol to water provides maximum antifreeze protection?

A) 100 percent
B) 60 percent
C) 30 percent
D) 20 percent

Question 12

When a cooling system using true ELC needs to be topped up, which of the following is correct?

A) drain and flush system
B) add premix
C) add distilled water only
D) add ELC and distilled water mixture

Question 13

What causes wet liner cavitation?

A) engine overheating
B) engine lugdown
C) bubble collapse
D) air in coolant

Question 14

Which of the following pH readings taken in engine coolant fall in the normal range?

A) 3.5
B) 6.0
C) 9.0
D) 13.5

Question 15

Which of the following is NOT true of an extended life coolant (ELC)?

A) no inhibitor testing required
B) lasts for up to six years
C) improves cavitation protection
D) never has to be inspected

Question 16

Which is the most accurate means of testing the antifreeze protection level of a coolant?

A) hydrometer
B) manometer
C) litmus paper
D) refractometer

Question 17

Which type of radiator uses a double pass principle?

A) downflow
B) crossflow
C) counterflow
D) upflow

Question 18

How much is coolant boil point raised in a sealed cooling system for each one psi above atmospheric pressure?

A) one degree Fahrenheit
B) three degrees Fahrenheit
C) five degrees Fahrenheit
D) eight degrees Fahrenheit

Question 19

When truck radiator hoses collapse internally as an engine cools, which of the following components should be checked out first?

A) water pump
B) radiator cap
C) thermostat
D) fanstat

Question 20

Which component in a truck cooling system requires that the coolant has some lubricating properties?

A) water pump
B) radiator shutters
C) thermostat
D) intercooler

Question 21

When rebuilding a diesel engine water pump, which of the following components has to be handled with a great amount of care?

A) steel impellers
B) plastic impellers
C) drive pulley
D) ceramic seal

Question 22

What device is used to signal engine coolant temperatures on most current diesel engines?

A) PTC thermistor
B) NTC thermistor
C) expansion tube
D) bimetal electric sensor

Question 23

When coolant is routed through the bypass circuit, which of the following is probable?

A) engine is overheating
B) thermostat is fully open
C) thermostat is fully closed
D) coolant is routed to the radiator

Question 24

In an older truck cooling system using radiator shutters, what would happen if the air supply to the shutterstat failed?

A) engine overheat
B) shutters remain closed
C) shutters remain open
D) shutters rapidly cycle

Question 25

Which type of thermally managed fan has no external controls?

A) thermatic viscous drive
B) electrically engaged
C) fanstat controlled
D) ?

Question 26

Which of the following could be handled by data bus communications in a current diesel engine cooling system

A) thermostat opening
B) A/C to fan-engage command
C) coolant flow through heater core
D) shutter cycling

Question 27

Technician A says that diesel engines equipped with water manifolds have more even actual cylinder temperatures. Technician B says that in engines not equipped with water manifolds, the cylinders closest to the radiator are likely to run warmer when the engine is at operating temperature. Who is correct?

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

Question 28

What is the pumping member of a diesel engine water pump rotor known as?

A) propeller
B) impeller
C) turbo
D) gerotor

Question 29

Technician A says that downflow radiators use a double pass flow principle. Technician B says that a counterflow radiator uses double pass flow routing. Who is correct?

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

Question 30

Technician A says that loose fan belts are usually destroyed more rapidly than belts that are adjusted too tight. Technician B says that too tight adjustment on poly-V fan belts can destroy bearings. Who is correct?

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

Question 31

What should always be used to adjust fan belts?

A) torque wrench
B) fish weight scale
C) belt dressing spray
D) belt tension gauge

Question 32

Technician A says that the first step to take when troubleshooting an engine overheating conditioning is to remove the radiator shroud to permit unimpeded air flow through the engine compartment. Technician B says that an engine overheat condition could be caused by a missing or damaged radiator shroud. Who is correct?

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

Question 33

When considering coolant cavitation erosion, what is a vapor bubble composed of?

A) air
B) vaporized coolant
C) blow-by gas
D) vaporized engine lube

Question 34

Which type of engine coolant offers the best protection against liner cavitation erosion?

A) PG
B) ELC
C) EG
D) WEC

Question 35

How does waterless engine coolant (WEC) protect against liner cavitation erosion?

A) oxyalate additives
B) provides vastly superior anti-boil properties
C) boils at lower temperatures than EG
D) gels on liner wall