Ch. 21 Cooling System Operation & Diagnosis

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All of the following are methods for thermostat​ testing, except the​ ________.

warm booting method

A water pump is a positive displacement type of pump.

True

Which of the following is a common cause of overheating in an​ engine?

broken fan drive belts

Technician A says that the radiator should always be inspected for leaks and proper flow before installing a rebuilt engine. Technician B says that overheating during slow city driving can only be due to a defective electric cooling fan. Which technician is correct?

Both technicians A & B

What can be done to prevent air from getting trapped in the cooling system when the coolant is replaced?

Use a coolant exchange machine that draws a vacuum on the system AND open the air bleeder valve while adding coolant.

The powertrain control module​ (PCM) in a vehicle commands​ low-speed fans on under the following conditions except when the​ ________.

system voltage is less than 12 volts after the vehicle is shut off

If the warning light comes on during driving or the temperature gauge goes into the red danger​ zone, then the coolant temperature is most likely​ ________.

120 to 126 degrees C

The normal operating temperature (coolant temperature) of an engine equipped with a 195 degree F thermostat is ____.

195 to 215 degrees F

The boiling temperature of the coolant will most likely increase by​ ________ for each pound of increase in pressure.

3 degrees F

The upper radiator hose collapses when the cools. What is the most likely cause?

A defective pressure cap

When checking coolant level in the expansion​ tank, the technician sees that the tank is empty. What could this​ indicate?

A leak in the recovery tank hose

Which of the following is true of coolant recovery​ systems?

A vacuum valve allows coolant to reenter the system.

The powertrain control module​ (PCM) in a vehicle commands the​ high-speed fan when the​ ________.

A/C refrigerant pressure exceeds 240 PSI

When checking coolant level in the expansion​ tank, what is the correct​ reading?

Above the MIN level marker and below the MAX level marker

Water pumps _________.

Are driven by the engine crankshaft or camshaft

Two technicians were discussing coolant recovery systems in vehicles. Technician A stated that when the system​ cools, the pressure in the cooling system is reduced and a partial vacuum forms. Technician B stated that vacuum pulls the coolant from the plastic container back into the cooling​ system, keeping the system full. Which of the following statements about this scenario is​ true?

Both technician​ A's and​ B's assessments are accurate.

Two technicians were discussing the characteristics of heater cores in automotive cooling systems. Technician A stated that heated coolant is passed through tubes in the small core of the heater.Technician B stated that air is passed across the heater fins and is then sent to the passenger compartment. Which of the following statements about this scenario is​ true?

Both technician​ A's and​ B's assessments are accurate.

Two technicians were discussing the ways to specify whether the belt tension is within factory specifications. Technician A stated that the belt should be installed and the engine should be operated with all of the accessories turned on. Technician B stated that a​ beam-type torque wrench should be used to determine the torque needed to rotate the tensioner. Which of the following statements about this scenario is​ true?

Both technician​ A's and​ B's assessments are accurate.

The radiator pressure tester is used to check​ ________.

Both the radiator for leaks and the pressure cap

How does the technician know the pressure rating for the cooling​ system?

Check the radiator cap

On an overheating engine the coolant can be tested for the presence of​ ________.

Combustion gases

What happens to the cooling system flushing chemical during a flushing​ service?

It is removed with clean water.

Which of these could cause an engine overheating​ problem?

Loose cylinder head bolts

A missing fan shroud could cause​ ________.

Overheating

What diagnostic trouble code (DTC) could be set if the thermostat is defective?

P0128

A customer complains that the heater works sometimes, but sometimes only cold air comes out while driving. Technician A says that the water pump is defective. Technician B says that the cooling system could be low on coolant. Which technician is correct?

Technician B only

Heat transfer is improved from the coolant to the air when the ____.

Temperature different is great

What tools can be used to test​ coolant?

Test strips, a hydrometer, and a refractometer

What components need to be removed when replacing a​ radiator?

The cooling fans

Part of servicing an electric radiator fan is to first disconnect the fan electrical connector. Why is​ this?

The fan may turn on at any time

Which of the following is an appropriate precautionary measure when the coolant temperature warning light comes​ on?

The radiator cap should not be removed when the engine is hot.

Which of the following is true of thermostat​ operation?

The rated temperature of the thermostat indicates the temperature at which the thermostat starts to open.

Which state is true about thermostats?

The temperature marked on the thermostat is a temperature at which the thermostat should start to open.

To replace a​ radiator, the upper and lower hoses must be disconnected.​ Also, disconnect the​ ________ lines.

Transmission cooler

Which of the following is true of water​ pumps?

Water pumps are not positive displacement pumps.

Which of the following is true of the cooling system​ service?

When flushing the cooling​ system, an engine should be started until it reaches operating temperature with the heater on.

In series flow cooling​ systems, ________ in the​ gasket, block, and head perform the function of letting out the steam.

bleed holes

The​ ________ must allow the engine to warm up to the required operating temperature as rapidly as possible and then maintain that temperature.

cooling system

In​ ________ radiators, the coolant flows from one side of the radiator to the opposite side.

cross-flow

Coolant exchange machines can perform the following​ functions, except​ ________.

filter the coolant of impurities

A hydrometer is used to test the​ ________ of the coolant.

freezing point

A special​ ________ is used to fill and bleed the air from the cooling system.

funnel

All of the following are causes of overheating in an​ engine, except​ ________.

high engine oil level

Which of the following is most likely a​ high-temperature engine​ problem?

sticky hydraulic valve lifter plungers


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