Ch. 21 Cooling System Operation & Diagnosis
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
