Heat Test
In a modern cooling system, the coolant level is cehcked at the...
coolant recovery reservoir and the radiator
pressurizing the automotive cooling system results in...
increased coolant boiling point
When replacing a stretch-type belt, the old belt can be removed by cutting it off.
True
a large vehicle or SUV may have a second heater core in the rear of the vehicle
True
Heater function diagnosis should start with...
coolant condition and level
A 50/50 mixture of ethylene glycol and water freezes at what temperature?
-34 F
In a modern cooling system with an expansion tank, the coolant level is check at the...
coolant recovery reservoir
modern cooling systems are designed to maintain an engine temperature of...
180-230 F
The normal operating temperature of an engine equipped with a 195 thermostat is...
195 to 215F
The boiling point of water with a 15psi pressure cap is about...
250F
What is the total number of water pumps that can be found on a ford escape hybrid?
3
Antifreeze concentration should be at least .... but not more than...
40%, 60%
A 5 ribbed serpentine belt should be tensioned at about...
75 - 100lbs
A hybrid vehicle may use which of the following to warm the vehicle occupants?
A heat pump, an auxiliary water pump, or PTC heater elements
After the water pump was replaced and the cooling system refilled with coolant, the heater stopped providing warm air. Which of these is most likely the cause?
An air pocket is trapped in the heater core
Tech A says a 50/50 mixture of ethylene glycol and water mixture lowers the freezing point of the coolant below that of water. Tech B says a 50/50 mixture of ethylene glycol and water raises the boiling point of the coolant above that of water. Who is correct
Both
Tech A says that a cooling system should hold pressure when its pressure is checked. Tech B says that the pressure tester can also be used to check for combustion leaks. Who is correct?
Both
Tech A says that a heater core leak can be the result of the coolant wearing a hole through the core. Tech B says that a core leak can be caused by chemical action eating a hole through the core. Who is correct?
Both
Tech A says that a leaky heater core may show up as a drip onto the carpet. Tech B says that you can test a heater core for leaks using a pressure tester. Who is correct?
Both
Tech A says that after service, it is good practice to retighten hose clamps after the engine has been run and then cooled down. Tech B says that when coolant is replaced, the coolant level should be checked after the engine has thermocycled. Who is correct?
Both
Tech A says that cooling fans are designed to draw air through the radiator to aid in the heat transfer process. Tech B says that drawing the heat from the coolant transfers this heat to the outside air through the radiator. Who is correct?
Both
Tech A says that faulty heater operation can be caused by a faulty engine cooling system. Tech B says that a complaint of insufficient heat can be caused by someone not filling a cooling system properly. Who is correct?
Both
Tech A says that the use of a coolant recycling station reduces the need for system bleeding. Tech B says that the use of a coolant recycling station reduces the need for hazardous waste disposal. Who is correct?
Both
Tech A says the cooling system must be full for a pressure test to be effective. Tech B says the cooling system should not be pressurized beyond the pressure cap rating. Who is correct?
Both
Tech A says the radiator outlet is connected to the water pump inlet by a rubber hose. Tech B says the thermostat is usually located at the engine coolant outlet. Who is correct?
Both
Tech A says when the engine is running with the thermostat closed, the coolant is directed through a bypass system to ensure coolant circulation. Tech B says coolant can flow through the heater core when the thermostat is closed. Who is correct?
Both
The coolant heat storage system is being discussed. Tech A says that the water valve is driven by an electric motor. Tech B says that the storage tank has its own electric water pump. Who is correct?
Both
Two techs are discussing heater temperature control. Tech A says that a control valve will be wide open when full heat is desired. Tech B says the coolant control valve should go wide open if the vacuum line is disconnected. Who is correct?
Both
Two techs are discussing the heater core. Tech A says that a heater core is a heat exchanger much like a radiator. Tech B says the coolant from the engine brings the heat to the heater core. Who is correct?
Both
Two techs are testing a radiator pressure cap using a cooling system pressure tester. Tech A says the pressure cap should not leak at a pressure below its rating. Tech B says it must open at its rated pressure. Who is correct?
Both
A vehicle's engine temperature gauge is reading higher than normal and the radiator fan does not operate. Tech A says that no continuity across the fan motor could be the cause. Tech B says that an open radiator fan fuse could be the cause. Who is correct?
Both technicians
Tech A says the most common cooling system problems are the result of leaks. Tech B says coolant pump leaks are often caused by worn bearings. Who is correct?
Both technicians
A customer complains that the engine is overheating. While inspecting the vehicle when it is hot, it is found to have excessive coolant in the coolant recovery container. After the engine cools the level returns to normal. Tech A says that this could be caused by a restriction in the radiator. Tech B says that a blown head gasket could also cause this. Who is correct?
Both techs
Tech A says a defective radiator cap vacuum valve may cause hoses to collapse. Tech B says a defective pressure valve may cause coolant boil over and loss. Who is correct?
Both techs
during a routine fluid level inspection, a radiator is found to be low on coolant, but the coolant recovery tank was at the proper level. Tech A says that a faulty radiator cap could be the cause. Tech B says that a cracked radiator to recovery tank hose could be the cause. Who is correct?
Both techs
The heater core uses... to produce heat.
Engine coolant
Tech A says that because of hybrid/electric technology, the internal combustion engine used on these vehicles runs colder than peak operating temperatures. Tech B says that PTC coolers located in the A/C system are used to overcome this excessive engine heat. Who is correct?
Neither tech
Tech A says that the cooling system should be tested for leaks using an air-operated pressure pump. Tech B says the freezing and boiling point of the coolant can be tested using a thermometer. Who is correct?
Neither?
electric cooling fans are typically commanded on and off by the...
PCM
On a toyota camry hybrid, what component heats the passenger compartment in addition to the conventional heater core?
PTC electric heater
Tech A says that a fan clutch operation can be tested using a strobe light. Tech B says that the fan clutch should be locked up when the engine is cold. Who is correct?
Tech A
Tech A says that the purpose and function of the cooling system is to maintain proper engine operating temperature. Tech B says that the water pump control's engine coolant temperature by opening at its rated opening temperature to allow coolant to flow through the radiator. Who is correct?
Tech A
Tech A says that the thermostat test begins with the engine cold. Tech B says that a good thermostat allows coolant to circulate immediately. Who is correct?
Tech A
Two techs are discussing antifreeze. Tech A says that green antifreeze should be changed every year or two to keep a cooling system clean. Tech B says that an overheating system can be kept from boiling by using straight antifreeze for a coolant. Who is correct?
Tech A
Two techs are discussing the coolant flow through a heater core. Tech A says that heated coolant enters the heater inlet close to the engine thermostat. Tech B says the coolant from the heater core returns to the water pump outlet. Who is correct?
Tech A
Two techs are discussing the heater output temperature. Tech A says that a valve is used to reduce coolant flow through the core when less heat is desired. Tech B says that most modern systems use a blend-air door to control the coolant flow. Who is correct?
Tech A
All of the following conditions could cause engine coolant loss EXCEPT...
a leaking transmission cooler lines
A customer complains of engine overheating, only at idle. The system is full of coolant and the belts are properly adjusted. Tech A notices a missing fan shroud and says that could be the cause of the problem. Tech B says a thermostat stuck closed is a more likely cause of the problem. Who is correct?
Tech A only
An engine overheats when the vehicle is parked, with the engine running. When the vehicle is driven at highway speeds, the engine operates at the normal temperature. Tech A says an inoperative electric radiator cooling fan could be the cause. Tech B says a seized thermostatic fan clutch could be the cause. Who is right?
Tech A only
Tech A says a purpose of a thermostat is to cause the engine to warm up as soon as possible. Tech B says the thermostat should be removed from the cooling system only if the engine is overheating. Who is correct?
Tech A only
Tech A says excessive engine heat is a product of combustion. Tech B says the average automotive engine wastes heat energy that is removed in the exhaust and radiator. Who is correct?
Tech A only
Tech A says if coolant is not reused, it must be disposed of or recycled in an environmentally safe manner. Tech B says it is okay to mix standard ethylene glycol in a cooling system containing extended life coolant; it will not affect the corrosion protection rating. Who is correct?
Tech A only
Tech A says one should always follow OEM specifications for a radiator pressure cap rating. Tech B says a defective radiator pressure cap could cause overheating. Who is correct?
Tech A only
Tech A says that PTC heaters can be built into a conventional heater core assemble. Tech B says that a PTC heater's electrical resistance will decrease as its temperature increases. Who is correct?
Tech A only
Tech A says thermostats open and close gradually as the temperature of the coolant increases or decreases. Tech B says a thermostat is not needed if the vehicle is only driven for short distances. Who is correct?
Tech A only
Tech A says that the automotive water pump is a positive displacement-type pump. Tech B says that the water pump could be driven by the camshaft. Who is correct?
Tech B
Tech A says that the coolant heat storage tanks used in some HEVs are made of an inner and outer casing with pressurized gas in between for insulation. Tech B says that coolant heat storage tanks in HEVs contain a vacuum between the inner and outer linings. Who is correct?
Tech B
Tech A says that the high voltage batteries in all hybrid electric vehicles are cooled and maintained at the same temperature as the engine's coolant system. Tech B says many hybrid vehicle high voltage systems are water cooled by separate cooling systems that operate in much the same way as the engine cooling system. Who is correct?
Tech B
Tech A says that the major cause of engine overheating is a faulty thermostat that opens at a too-high temperature. Tech B says that the bleed notch or jiggle pin should be at the top when installing vertically mounted thermostats. Who is correct?
Tech B
Two techs are discussing coolant circulation. Tech A says that coolant flows from the bottom to the top in older radiator designs. Tech B says that the coolant flow from one side of the radiator to the other in a crossflow design. Who is correct?
Tech B
Two techs are discussing fan clutches. Tech A says that some fan clutches have a thermostatic valve that allows the clutch to drive the fan when it is cool. Tech B says that some fan clutches reduce noise level and engine power loss at higher RPMs. Who is correct?
Tech B
Two techs are discussing system flushing. Tech A says the best way to flush a system is in the direction of normal coolant flow. Tech B says that a system should be flushed until clean water flows out of the system. Who is correct?
Tech B
While discussing coolant changes, Tech A says that the old coolant can simply be poured down the drain. Tech B says that used coolant must be recycled. Who is correct?
Tech B
While discussing cooling system operation, Tech A says that the engine will overheat if the thermostat sticks in the open position. Tech B says that the heater operation will be affected if the thermostat sticks open. Who is correct?
Tech B
A vehicle in for repair has a burst upper radiator tank. Tech A says a thermostat that was stuck in the open position could be the cause. Tech B says that a faulty radiator pressure cap could be the cause. Who is correct?
Tech B only
Tech A says a radiator pressure cap holds pressure in the cooling system to decrease the freezing point of the coolant. Tech B says the coolant pressure increases because the coolant temperature increases. Who is correct?
Tech B only
A customer complains that the heater works sometimes, but sometimes only cold air comes out while driving. Tech A says that the water pump is defective. Tech B says that the cooling system could be low on coolant. Who is correct?
Tech B only.
An engine that runs too cold can cause
The MIL to come on, poor transmission performance, poor fuel mileage
Which statement is true about thermostats?
The temperature marked on the thermostat is a temperature at which the thermostat should start to open
An engine has a coolant leak. The technician diagnosed the source of the leak is a core plug that corroded. He measured the coolant for electrolysis and confirmed that it is way too high and is the cause of the core plug decomposition. What is the root cause of the electrolysis.
There is an electrical circuit running through the coolant.
A coolant heat storage tank can keep coolant warm for a maximum of ... days.
Three
A hybrid vehicle may have more than one cooling system.
True
A missing lower radiator hose spring can cause engine overheating.
True
A hybrid vehicle may have a tendency to have low coolant temperatures. This is due to...
Vehicle idle - stop feature
The water pump drive belt should be checked for...
Wear using a gauge, condition, proper tension
In a hybrid vehicle, heat may be added to the heater by...
a PTC ceramic element
Which of the following could cause symptoms of overcooling even though the engine temperature is normal?
a defective temperature sending unit
A vehicle is in for service with a complaint of poor heat output. The technician finds air trapped in the heater core. What is most likely cause of this condition?
a leaking cylinder head gasket
A pressure gauge is installed on the radiator filler neck and the system pressurized to 15psi. After a few minutes, the pressure was down to 5psi according to the gauge on the tester. What is the least likely cause?
a leaking evaporator
A customer complains about engine coolant loss. The cooling system is pressurized at 15psi for 15 minutes. There is no visible sign of coolant leaks in the engine or passenger compartments, but the pressure on the tester gauge decreases to 5psi. This problem could be caused by any of the following defects EXCEPT:
a leaking heater core
A customer complains that 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?
a partially blocked heater core
A lack of heat from the heater is being diagnosed. Which is the MOST LIKELY cause?
a partially clogged heater core
on most vehicles with a serpentine belt, the belt is tensioned by...
a spring loaded tensioner
A heater control valve may be operated by:
a vacuum actuator
Antifreeze pH level should be... or it will be too acidic and cause corrosion and failure of cooling system components
above 7.0
The use of a coolant recovery machine is helpful in preventing... from entering the cooling system
air
When checking a heater for a no heat concern, both hoses are found to be too hot to hold. What could be the cause of no heat in the vehicle?
air blend door fault
With most cars, heater outlet temperature is adjusted by controlling the flow of ... through the heater core
air or coolant
What is the purpose of a flow restrictor, if used?
allow for a better heat transfer to the fins/air, slow the coolant velocity as it passes through the heater core, reduce noise
What is used to help keep the passenger compartment warm during idle-stop operation?
an auxiliary electric water pump
some vehicles can operate the heater even when the engine is turned off. This is done by using...
an auxiliary water pump
Water pumps...
are driven by the engine crankshaft or camshaft
Tech A says a thermostat which opens too soon can cause poor heater operation. Tech B says low coolant level can cause poor heater operation. Who is correct?
both
Two techs are discussing coolant flow. Tech A says that you should not be able to feel a coolant flow through the upper radiator hose while the engine is cold. Tech B says that when the thermostat opens, the upper hose should start getting hot and you should feel a flow through it. Who is correct?
both
Two techs are discussing fan clutches. Tech A says that some fan clutches have a thermostatic valve that allows the clutch to drive the fan when it gets hot. Tech B says that a fan clutch allows a large fan to be used with a lower noise level and power loss. Who is correct?
both
Two techs are discussing radiator removal. Tech A says that you should use two wrenches as you loosen the cooler lines to the automatic transmission. Tech B says that cooler lines on modern vehicles might require special tools to disconnect the quick-connect-type coupler system. Who is correct?
both
on most engine blocks, the coolant flow is into the...
bottom and out the top
A scan tool can be used when diagnosing heater problems. The tool can check for all of these EXCEPT...
coolant flow rate
What type of pump is a typical water pump?
centrifugal
The water pump uses which of these actions to circulate the coolant?
centrifugal force
heater hoses are attached to the core using...
clamps and quick connect couplings
An aftermarket heater system consists of...
control switches, a heater core, a blower motor
All of the following statements about cooling systems are true EXCEPT...
coolant systems must be recovered, recycled, or handled as hazardous waste
what is commonly wrong when the heat from a heater "comes and goes"?
cooling system is low on coolant
An electric cooling fan may be controlled by...
cooling system temperature, and A/C system operation
The upper radiator hose collapses when the engine cools. What is the most likely cause?
defective pressure cap
The two basic design types of radiators are
down flow and cross flow
An automotive engine that is running at too high of a temperature will have which of these?
excessive oil consumption
A thermostat that is stuck open causes the engine to overheat
false
Insufficient heat output from a heater can be caused by a ....
faulty thermostat, plugged heater core, air pocket
Which of the following is true about heat?
heat always travels from something warm to something cold, cold is the lack of heat, heat is a form of energy
All of the following statements about engine cooling are true, EXCEPT
heat is transferred throughout the engine by radiation
A typical vehicle heater works by...
heat transfers from the coolant, to the fins, and to the air passing through the core
A seat filter is used with what type of system?
heated and cooled seats
Most cars use... to warm the passenger compartment.
hot coolant
Where is the coolant storage tank located on a 2004 Toyota prius?
in front of the left front wheel
The temperature gauge approaches the red part of the temperature gauge if driven at slow speeds but does not overheat if driven at highway speeds. What is the most likely cause?
inoperative cooling fan
A unique feature of a thermosyphon cooling system is that...
it has no water pump
On a 2010 toyota prius, what is the purpose of the solar panel?
it operates the blower motor
If the cooling system is low on coolant, what is a common symptom?
lack of heat from the heater, but only when the vehicle is at idle, yet plenty of heat when the engine is operating at highway speeds
What is the most likely cause of a heating system that fogs the windshield and leaves an oily film on the inside of the glass?
leaking heater core
If a thermostat fails in the open position, all of the following will occur EXCEPT
loss of coolant
This is NOT a purpose of the radiator cap:
lower boiling point of coolant
The heater control valve, if used, shuts off the coolant flow to the heater core when what setting is selected?
max cooling
All of these statements regarding Hybrid electrical component cooling systems are true EXCEPT
most of these systems use thermostats to regulate coolant flow
coolant is hottest in which area?
near the thermostat
Tech A says the engine thermostat is fully open at its rated temperature. Tech B says a higher rated thermostat should be installed if the vehicle's heater system is not blowing hot air. Who is correct?
neither
The customer concern is poor heater operation, and the top radiator hose and both heater hoses are at 160F. Tech A says this problem is caused by a plugged heater core. Tech B says the thermostat must be stuck open. Who is correct?
neither
Two techs are discussing heater hoses. Tech A says that most hoses have an inside diameter or about one inch or larger. Tech B says the heater core inlet hose is usually larger than the outlet. Who is correct?
neither
Two techs are discussing thermostats and coolant circulation. Tech A says that the coolant does not circulate while the thermostat is closed. Tech B says that the heater doesn't blow warm air while the engine is cold beacuse of this. Who is correct?
neither
tech A says that the fan used with modern RWD vehicles always rotates in a clockwise direction, the same as the crankshaft. Tech B says that the fan clutch used on FWD vehicles can cause fan rotation in either direction. Who is correct?
neither
The amount of power required to drive a fan is affected by the...
number of blades, blade pitch, and diameter
A thermostat in the cooling system helps prevent...
overcooling
If a cooling system operates at too cool of a temperature, the engine will...
produce higher emissions
Of the two general antifreeze chemicals that we studied, which one is never installed in vehicles at the factory and only used in the aftermarket?
propylene glycol
An engine block heater is used on some vehicles in very cold climates in order to...
provide faster engine warm up
Which of these can cause a belt to wear or fail prematurely?
pulley misalignment
Which component releases excess pressure from the cooling system?
radiator cap
An engine coolant temperature switch or air conditioner select switch is used to energize the...
radiator fan motor relay
A heater core has had sediment buildup; to remove it by backflushing:
run water into the heater core outlet
A 50/50 coolant mixture will provide extra protection against...
rust formation, hot spots in the engine, and boil over
most modern vehicles use a ... type drive belt.
serpentine
scan data indicates that the starter-generator control module on a GM hybrid pickup has overheated. The LEAST likely cause would be...
stuck thermostat
Heat transfer is improved from the coolant to the air when the...
temperature difference is great
what coolant is used in a motor/electronics cooling system
the same coolant that is used in the ICE cooling system
some cars use metal tubing for coolant flow to the core to allow routing...
through very congested arease with tight bands, or past very hot places
clutch fans are tested using a
timing light
Why is a coolant heat storage tank used on some HEVs?
to warm the ICE very quickly after cold starts for reduced exhaust emissions
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 valves while adding coolant.
what helps prevent water pump cavitation?
using the specified radiator cap
A vehicle has a noise from the FEAD belt area. Which component is a possible cause of the squeal?
water pump with worn bearings, power steering pump with worn bearings, loose and slipping belt
heat is transferred from the hot coolant flowing through the... to warm the air flowing through the fins of the heater core
water tubes
How does a thermoelectric device work?
when electrical current flows through the module, one side is heated and the other side is cooled
A vehicle has a cracked engine block and coolant is leaking into a cylinder and burning. What color is the exhaust smoke from burning coolant?
white