Question 1

All of the follow are true about engine thermostats EXCEPT:

Accepted Answer

A faulty thermostat should be replaced, not removed, for the proper functioning of the engine.

Question 2

Technician A says a defective radiator cap vacuum valve may cause hoses to collapse.Technician B says a defective pressure valve may cause coolant boil over and loss.Who is correct?

Accepted Answer

Both technicians are correct. A defective radiator cap vacuum valve may not allow air to enter the cooling system, causing the hoses to collapse. A defective pressure valve may not allow pressure to escape from the cooling system, causing the coolant to boil over and be expelled, resulting in coolant loss.

Question 3

To safeguard other cooling system components,a defective pressure cap should be replaced with one having a lower pressure rating.

Accepted Answer

To safeguard other cooling system components, a defective pressure cap should be replaced with one having the same pressure rating or a higher pressure rating, not a lower rating. This ensures that the system can handle the pressure and avoid damage to other components.

Question 4

It is okay to mix standard ethylene glycol in a cooling system containing extended life coolant; it will not affect the corrosion protection rating.

Accepted Answer

Mixing standard ethylene glycol with extended life coolant can result in a loss of corrosion protection, as the two types of coolant may have different additive packages that can react negatively with each other. It is important to only use the recommended coolant for your specific vehicle to ensure optimum performance and protection.

Question 5

All of the following statements about engine cooling are true,EXCEPT:

Accepted Answer

Heat transfer in engine cooling systems primarily involves conduction and convection, not radiation. Radiation plays a minimal role in the cooling of engine components compared to conduction (direct heat transfer through materials) and convection (heat transfer through fluid movement, such as coolant flowing through the engine and then to the radiator).

Question 6

If coolant in not reused,it must be disposed of or recycled in an environmentally safe manner.

Accepted Answer

Coolant cannot simply be discarded as it can be harmful to the environment. It must either be disposed of or recycled in an environmentally safe manner, following local regulations and guidelines.

Question 7

The temperature rating marked on a thermostat is the temperature at which it begins to open.

Accepted Answer

The temperature rating on a thermostat indicates the temperature at which it starts to open the contacts or switch off the heating/cooling system.

Question 8

Coolant pump leaks are often caused by worn bearings.

Accepted Answer

Coolant pump leaks are often caused by worn bearings. When the bearings wear out, it can cause the pump to wobble and create a leak in the gasket or seal.

Question 9

A thermostat is not needed if the vehicle is only driven for short distances.

Accepted Answer

A thermostat is needed in a vehicle regardless of the distance it is driven. The thermostat helps regulate the engine temperature and prevent overheating, which can occur even with short distances.

Question 10

The two basic design types of radiators are

Accepted Answer

The two basic design types of radiators are down flow and cross flow. In a down flow radiator, coolant flows from the top to the bottom. In a cross flow radiator, coolant flows from one side to the other.

Question 11

All of the following conditions could cause poor passenger compartment heating system performance EXCEPT:

Accepted Answer

A thermostat stuck in the closed position would cause the engine to overheat rather than affect the heating system's performance directly. The other options directly impact the flow of hot coolant through the heater core, which is necessary for proper heating system performance.

Question 12

A vehicle in for repair has a burst upper radiator tank.Technician A says thermostat htat was stuck in the open position could be the cause.Technician B says that a faulty radiator pressure cap could be the cause.Who is correct?

Accepted Answer

A faulty radiator pressure cap can cause excessive pressure build-up in the cooling system, leading to a burst radiator tank. A thermostat stuck open would not cause this issue.

Question 13

The engine cooling system is designed to remove about 80 percent of the total engine heat.

Accepted Answer

The engine cooling system is designed to remove about one-third of the total engine heat, with the rest being expelled through the exhaust system and radiation.

Question 14

Technician A says that serpentine belts made of EPDM resist cracking and instead exhibit wear to the belt ribs similar to tire wear and that a depth gauge should be used to assess belt wear.Technician B says that as a neoprene serpentine belt ages and wears that cracks will form on the belt ribs and that if there are more than 3 cracks in a 3 inch span the belt should be replaced.Who is correct?

Accepted Answer

Both technicians are correct. Technician A is correct in stating that EPDM belts show wear similar to tire wear and require a depth gauge for assessment, while Technician B is correct about neoprene belts cracking with age and the criteria for replacement based on the number of cracks.

Question 15

After a vehicle has been driven for 10-15 miles,the heater still continues to blow cool air.Which of the following is the most likely cause?

Accepted Answer

A partially blocked heater core can prevent hot coolant from circulating properly, resulting in the heater blowing cool air even after the engine has warmed up.

Question 16

Some radiator fan motors will start and run without warning.

Accepted Answer

Some radiator fan motors have a tendency to start and run without warning, and this can be due to various reasons such as a faulty fan relay, a damaged fan motor, or a malfunctioning temperature sensor. It is important to regularly inspect and maintain the cooling system of a vehicle to avoid any unexpected issues.

Question 17

The most common cooling system problems are the result of leaks.

Accepted Answer

Leaks in the cooling system can cause a loss of coolant, which can lead to overheating and engine damage. Therefore, leaks are a common problem in cooling systems.

Question 18

If a thermostat fails in the open position,all of the following will occur,EXCEPT:

Accepted Answer

If the thermostat fails in the open position, the coolant will circulate continuously, leading to a cooler engine running temperature. This leads to longer than normal warm-up period and poor heater performance. Also, the engine computer will receive a signal indicating that the engine is not warming up at the correct rate, leading to adjustments in the fuel mixture, which may cause erratic computer control system operation. However, there will not be any loss of coolant since the coolant is continuously circulating through the engine.

Question 19

Technician A says excessive engine heat is a product of combustion.Technician B says the average automotive engine is only 15 percent efficient.Who is correct?

Accepted Answer

Technician A is correct, as excessive engine heat is indeed a product of combustion. Technician B is also correct, as the average automotive engine is only around 15 percent efficient, meaning that a large portion of the energy produced by the engine is lost as heat. Therefore, both technicians are correct.

Question 20

Thermostats open and close gradually as the temperature of the coolant increases or decreases.

Accepted Answer

Thermostats are designed to gradually open and close as the temperature of the coolant increases or decreases in order to maintain a consistent engine operating temperature. This gradual response helps prevent rapid temperature changes that can cause engine damage.

Quiz 3: Engine Cooling and Comfort Heating Systemsdiagnosis and Service of Engine Cooling and Comfort Heating Systems