Question 1

If the engine overheats during long periods of idling but runs normally at highway speeds, the problem is most likely defective _____.

Accepted Answer

The cooling fan is responsible for pulling air through the radiator to cool the engine coolant when the vehicle is idling or moving slowly. If the engine overheats during idling but not at highway speeds (when air naturally flows through the radiator due to the vehicle's speed), it suggests the cooling fan may not be operating correctly to provide the necessary airflow for cooling.

Question 2

What does blue exhaust smoke indicate?

Accepted Answer

Blue exhaust smoke is a sign that oil is burning in the combustion chamber, which can happen due to worn seals, gaskets, or other engine components allowing oil to leak into areas where it can be burned along with the fuel.

Question 3

Water pumps are _____ type pumps.

Accepted Answer

The answer of Water pumps are _____ type pumps.
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Question 4

Technician A says cooling system pressure is regulated by the pressure relief valve in the water pump. Technician B says cooling system pressure is regulated by the radiator cap. Who is correct?

Accepted Answer

Cooling system pressure is regulated by the radiator cap, not by a pressure relief valve in the water pump. The radiator cap allows the system to maintain a certain pressure, and if the pressure exceeds the cap's rating, it allows coolant to flow to the overflow tank, thus regulating the system's pressure.

Question 5

Oil coolers are normally found on _____ vehicles.

Accepted Answer

Oil coolers are commonly used in diesel, high performance, and turbocharged vehicles to help manage and reduce engine oil temperatures, ensuring the engine runs efficiently and prolonging its lifespan.

Question 6

To drain a cooling system that does not have a petcock or drain plug in the radiator, ______.

Accepted Answer

Disconnecting the lower radiator hose is a common method to drain a cooling system when there is no petcock or drain plug available in the radiator. This allows the coolant to flow out from the lowest point in the system.

Question 7

The oil pressure ____________________ valve prevents excessively high system pressure from occurring as engine speed is increased.

Accepted Answer

The answer of The oil pressure ____________________ valve prevents excessively...

Question 8

Technician A says an electric cooling fan may come on at any time without warning, even if the engine is not running. Technician B says an electric cooling fan may be controlled by the engine control computer. Who is correct?

Accepted Answer

Both statements are correct. Electric cooling fans can indeed come on at any time, as they may be activated by the temperature of the engine coolant, not necessarily the engine running state. Additionally, modern vehicles often have their electric cooling fans controlled by the engine control computer (ECU/ECM), which decides when to turn the fan on or off based on various sensor inputs, including coolant temperature, air conditioning system pressure, and ambient temperature.

Question 9

The petcock valve is located _____.

Accepted Answer

The petcock valve is located at the bottom of the radiator. It is used for draining coolant from the radiator for maintenance or repairs.

Question 10

Two technicians are discussing oil filters. Technician A says the oil filter has an anti-drain-back valve that prevents the oil in the filter and engine oil passages from returning to the sump when the engine is shut down. Technician B says the oil filter has a bypass valve that in the event the filter becomes plugged, oil can flow directly to the bearings. Who is correct?

Accepted Answer

Both technicians are correct. Technician A is correct about the anti-drain-back valve, which prevents oil from draining out of the filter and passages when the engine is off, ensuring immediate oil pressure upon startup. Technician B is correct about the bypass valve, which allows oil to bypass the filter if it's clogged, ensuring the engine receives oil.

Question 11

Technician A says high crankcase pressure can be caused by worn piston rings. Technician B says low crankcase pressure can be caused by a faulty PCV system. Who is correct?

Accepted Answer

The answer of Technician A says high crankcase pressure can...

Question 12

Sludge is being discussed. Technician A says sludge results from the oxidation of oil. Technician B says a slight buildup on the underside of the oil fill cap is normal. Who is correct?

Accepted Answer

Technician A is correct because sludge indeed results from the oxidation of oil, which can occur when the oil is exposed to high temperatures and oxygen, leading to thickening and the formation of sludge. Technician B is also correct because a slight buildup of sludge on the underside of the oil fill cap can be considered normal, especially in colder climates where condensation can mix with the oil, creating a sludge-like substance. This doesn't necessarily indicate a severe problem unless the buildup is excessive.

Question 13

Which hose typically has a spiral wire reinforcement?

Accepted Answer

The lower radiator hose typically has a spiral wire reinforcement to prevent it from collapsing under suction from the water pump.

Question 14

During engine warm-up, when the thermostat is closed, _____.

Accepted Answer

During engine warm-up, when the thermostat is closed, coolant does not flow through the radiator. Instead, it flows through a bypass passage that allows the coolant to circulate within the engine block and heater core, helping the engine reach its operating temperature more efficiently.

Question 15

Two technicians are discussing a car with a very noisy water pump. The pump makes a lot of noise but is not leaking coolant. Technician A says the owner can continue to drive the vehicle as long as there are no signs on coolant leakage. Technician B says the water pump must be replaced immediately. Who is correct?

Accepted Answer

A noisy water pump, even without coolant leakage, can indicate bearing failure or imminent failure. It's unsafe to continue driving as it could lead to overheating or a sudden breakdown. Immediate replacement is advised.

Question 16

During routine service a small amount of engine oil is found in the air cleaner housing. Technician A says the PCV valve may be clogged. Technician B says the engine could be overfilled with oil. Who is correct?

Accepted Answer

The PCV valve is a one-way valve that allows crankcase gases to be drawn into the intake manifold. If the PCV valve is clogged, these gases will not be able to escape and will instead be forced into the air cleaner housing. This can cause engine oil to be deposited in the air cleaner housing.

Question 17

Technician A says a dry sump lubrication system eliminates the possibility of oil sloshing and possible oil starvation during hard cornering, braking, and acceleration. Technician B says a dry sump lubrication system allows the engine to be mounted higher in the frame. Who is correct?

Accepted Answer

A dry sump lubrication system uses a separate oil reservoir, which helps prevent oil sloshing and starvation during dynamic driving conditions. However, it allows the engine to be mounted lower, not higher, in the frame.

Question 18

Two technicians are discussing a vehicle with an overheating problem. There are no leaks, internal or external. The belts are in good condition, and the radiator has been removed and flow tested. Everything appears to be in good condition. A new thermostat was installed, but it did not cure the problem. What is most likely the problem?

Accepted Answer

The impeller slipping on the water pump shaft or the impeller blades being corroded can both lead to inadequate coolant circulation, causing overheating despite no leaks and a functioning thermostat.

Question 19

When testing a radiator cap, with the rated pressure applied, the cap should hold that pressure for at least _____.

Accepted Answer

A radiator cap should hold the rated pressure for at least 1 minute when tested. This ensures that the cap can maintain the necessary pressure in the cooling system to prevent boiling over and to ensure efficient cooling.

Question 20

If the fan shroud is removed from a vehicle, _____.

Accepted Answer

The fan shroud helps direct airflow through the radiator when the vehicle is idling or moving slowly, improving cooling efficiency. Without it, the engine is more likely to overheat during prolonged idling rather than at highway speeds, where natural airflow is sufficient to cool the engine.

Quiz 14: Lubricating and Cooling Systems