Question 1

Which of the following ingredients is added to diesel engine coolant to prevent cavitation?
A)Nitrite.
B)Silicate.
C)Ethylene glycol (EG).
D)Borate.

Accepted Answer

Nitrite is commonly added to diesel engine coolants to prevent cavitation by forming a protective layer on metal surfaces, reducing the risk of pitting and erosion.

Question 2

The presence of cavitation on the coolant side of the cylinder wall is most likely caused by __________.
A)lubrication breakdown
B)excessive cylinder pressures
C)excessive cooling system pressure
D)improperly conditioned coolant

Accepted Answer

Improperly conditioned coolant can lead to cavitation, as it may lack the necessary additives to prevent the formation of vapor bubbles that collapse and cause damage to the cylinder wall.

Question 3

Technician A says that blue antifreeze is long-life antifreeze. Technician B says that blue antifreeze is propylene glycol-based antifreeze. Who is correct?
A)Technician A
B)Technician B
C)Both A and B
D)Neither A nor B

Accepted Answer

B

Question 4

Technician A says that antifreeze is added to coolant to protect the coolant from freezing and to lower its boiling point. Technician B says antifreeze lowers the freeze point and raises the boiling point of coolant. Who is correct?
A)Technician A
B)Technician B
C)Both A and B
D)Neither A nor B

Accepted Answer

Antifreeze is added to coolant to lower its freezing point and raise its boiling point, not lower it. Technician B is correct.

Question 5

Which antifreeze will require the highest concentration to maintain 0°F (−18°C) freeze protection?
A)Ethylene glycol (EG).
B)Propylene glycol

Accepted Answer

Propylene glycol requires a higher concentration than ethylene glycol to achieve the same level of freeze protection because it has a lower freezing point depression efficiency.

Question 6

Technician A says that a drop in the coolant level in the surge tank or coolant overflow reservoir when the engine cools indicates an internal engine leak. Technician B says that the drop in the level is normal. Who is correct?
A)Technician A
B)Technician B
C)Both A and B
D)Neither A nor B

Accepted Answer

A drop in the coolant level in the surge tank or coolant overflow reservoir when the engine cools is normal due to the contraction of the coolant as it cools down.

Question 7

Technician A says the problem with new long-life antifreeze is it can produce silicate dropout, which plugs cooling system passages. Technician B says that the problem with some types of long-life antifreeze is that it is not compatible with all cooling system materials. Who is correct?
A)Technician A
B)Technician B
C)Both A and B
D)Neither A nor B

Accepted Answer

The answer of Technician A says the problem with new...

Question 8

Technician A says the oil-pressure regulator automatically reduces oil pressure at low-speed and low-load conditions. Technician B says that two-stage pressure regulation is performed electronically to reduce fuel consumption. Who is correct?
A)Technician A
B)Technician B
C)Both A and B
D)Neither A nor B

Accepted Answer

Technician B is correct because two-stage pressure regulation is often performed electronically to optimize engine performance and reduce fuel consumption. Technician A's statement is incorrect as oil-pressure regulators typically maintain pressure rather than reduce it at low-speed and low-load conditions.

Question 9

Which series of engine oils is used in a diesel engine?
A)S series.
B)ASTM.
C)C series.
D)SAE.

Accepted Answer

The "C series" of engine oils is specifically designed for diesel engines, where "C" stands for "Compression" ignition, which is characteristic of diesel engines.

Question 10

The 15W in 15W-40 engine oil stands for which of the following?
A)Multiviscosity.
B)Viscosity at 0°F (−18°C).
C)Viscosity at 212°F (100°C).
D)The thickness of the oil when cold.

Accepted Answer

The "15W" in 15W-40 engine oil indicates the oil's viscosity at low temperatures, specifically at 0°F (−18°C), where "W" stands for winter.

Question 11

Which of the following is the most recent engine oil made for a diesel engine?
A)SG-4.
B)CJ-4.
C)SJ.
D)FA-4.

Accepted Answer

FA-4 is the most recent engine oil specification for diesel engines, introduced after CJ-4, and is designed to provide better fuel efficiency and lower emissions.

Question 12

Diesel engine oil has which job of the following extra jobs to perform, which gasoline engines are not necessarily required to perform?
A)High-speed lubrication.
B)Cooling piston crowns.
C)Absorbing shock loading that engine parts can incur.
D)Sealing piston rings.

Accepted Answer

Diesel engines typically have higher compression ratios and can generate more heat, so diesel engine oil often has the additional job of cooling piston crowns.

Question 13

Technician A says that low-sulfur oil needs to be used today to prevent damage to exhaust aftertreatment systems. Technician B says that today's oils should have low ash content. Who is correct?
A)Technician A
B)Technician B
C)Both A and B
D)Neither A nor B

Accepted Answer

The answer of Technician A says that low-sulfur oil needs...

Question 14

Technician A says that viscosity index (VI) improvers thicken oil when it becomes hot and thins it when it becomes cold. Technician B says that VI improvers thin oil when it's hot and thicken it when it's cold. Who is correct?
A)Technician A
B)Technician B
C)Both A and B
D)Neither A nor B

Accepted Answer

Viscosity index (VI) improvers are additives that help to maintain the viscosity of oil over a wide temperature range. When the oil is hot, the VI improvers thicken the oil to prevent it from becoming too thin. When the oil is cold, the VI improvers thin the oil to prevent it from becoming too thick.

Question 15

What is the maximum percentage of soot loading that means engine oil needs to be changed?
A)2%.
B)5%.
C)10%.
D)20%.

Accepted Answer

The maximum percentage of soot loading in engine oil that typically indicates the need for an oil change is 5%. Beyond this level, the oil's ability to lubricate and protect the engine effectively is compromised.

Question 16

Technician A says that the cooling system pressurizes to enable coolant to remove more heat from the engine. Technician B says pressurization is needed to keep the coolant from boiling. Who is correct?
A)Technician A
B)Technician B
C)Both A and B
D)Neither A nor B

Accepted Answer

Pressurization of the cooling system raises the boiling point of the coolant, preventing it from boiling at higher temperatures.

Question 17

Technician A says that diesel engine oil turns black faster than oil in an SI engine because the oil composition and quality are different between the two oils. Technician B says that there is no difference between diesel engine and SI engine oil. Who is correct?
A)Technician A
B)Technician B
C)Both A and B
D)Neither A nor B

Accepted Answer

Diesel engine oil turns black faster due to soot and combustion byproducts, not because of different oil composition or quality. Both technicians are incorrect in their statements.

Question 18

Which of the following is the normal operating oil temperature of a diesel engine?
A)20°F to 30°F (5°C to 14°C) lower than coolant temperature.
B)Close to cooling system operating temperature.
C)30°F to 40°F (−1°C to 4°C) above cooling system temperature.
D)Approximately 250°F (121°C).

Accepted Answer

The answer of Which of the following is the normal...

Question 19

Which of the following will likely cause excessively high oil pressures?
A)A plugged oil filter.
B)A defective oil filter bypass valve.
C)A defective oil-pressure regulating valve.
D)A defective pressure-relief valve.

Accepted Answer

The answer of Which of the following will likely cause...

Question 20

Technician A says that spin-on oil filters in metal cans are being eliminated because they are less convenient and messy. Technician B says that cartridge-type filters are becoming more commonly used to allow them to be more easily disposed in a more environmentally friendly way. Who is correct?
A)Technician A
B)Technician B
C)Both A and B
D)Neither A nor B

Accepted Answer

The answer of Technician A says that spin-on oil filters...

Quiz 7: Diesel Engine Cooling and Lubrication Systems

Which of the following ingredients is added to diesel engine coolant to prevent cavitation?

The presence of cavitation on the coolant side of the cylinder wall is most likely caused by __________.

Technician A says that blue antifreeze is long-life antifreeze. Technician B says that blue antifreeze is propylene glycol-based antifreeze. Who is correct?

Technician A says that antifreeze is added to coolant to protect the coolant from freezing and to lower its boiling point. Technician B says antifreeze lowers the freeze point and raises the boiling point of coolant. Who is correct?

Which antifreeze will require the highest concentration to maintain 0°F (−18°C) freeze protection?

Technician A says that a drop in the coolant level in the surge tank or coolant overflow reservoir when the engine cools indicates an internal engine leak. Technician B says that the drop in the level is normal. Who is correct?

Technician A says the problem with new long-life antifreeze is it can produce silicate dropout, which plugs cooling system passages. Technician B says that the problem with some types of long-life antifreeze is that it is not compatible with all cooling system materials. Who is correct?

Technician A says the oil-pressure regulator automatically reduces oil pressure at low-speed and low-load conditions. Technician B says that two-stage pressure regulation is performed electronically to reduce fuel consumption. Who is correct?

Which series of engine oils is used in a diesel engine?

The 15W in 15W-40 engine oil stands for which of the following?

Which of the following is the most recent engine oil made for a diesel engine?

Diesel engine oil has which job of the following extra jobs to perform, which gasoline engines are not necessarily required to perform?

Technician A says that low-sulfur oil needs to be used today to prevent damage to exhaust aftertreatment systems. Technician B says that today's oils should have low ash content. Who is correct?

Technician A says that viscosity index (VI) improvers thicken oil when it becomes hot and thins it when it becomes cold. Technician B says that VI improvers thin oil when it's hot and thicken it when it's cold. Who is correct?

What is the maximum percentage of soot loading that means engine oil needs to be changed?

Technician A says that the cooling system pressurizes to enable coolant to remove more heat from the engine. Technician B says pressurization is needed to keep the coolant from boiling. Who is correct?

Technician A says that diesel engine oil turns black faster than oil in an SI engine because the oil composition and quality are different between the two oils. Technician B says that there is no difference between diesel engine and SI engine oil. Who is correct?

Which of the following is the normal operating oil temperature of a diesel engine?

Which of the following will likely cause excessively high oil pressures?

Technician A says that spin-on oil filters in metal cans are being eliminated because they are less convenient and messy. Technician B says that cartridge-type filters are becoming more commonly used to allow them to be more easily disposed in a more environmentally friendly way. Who is correct?