Cooling Systems Flashcards
Can you open a rad cap when the engine is hot?
No, can explode shooting coolant every where
Is coolant harmful?
Yes it is poisonous to animals and can also cause harm to groundwater supplies. Therefore coolant needs to be disposed of properly.
What are the functions of the cooling system?
- remove excess heat from the engine
- maintain a constant operating temperature under various driving conditions
- increases the engine to operating temperature as quickly as possible
- provide heat to the passenger compartment of vehicle
What is a typical engine operating temperature?
180F-210F
During combustion temperature can reach up to?
4000F (2484C)
What are two types of cooling systems?
Liquid cooling, air cooling
Describe how a liquid cooling system works.
Liquid (coolant) is used to absorb excess heat created during combustion. Coolant travels through the cylinder head and engine block to absorb heat and is then cooled off by the radiator.
Describe the air cooling system.
Large fins on the cylinders act as a heat sink, outside air cools the fins. Plastic or metal ducts direct outside air over the fins.
What are the advantages of using liquid cooling.
- more precise control of engine operating temp
- less engine temp fluctuations
- reduced exhaust emissions
- increased fuel economy
- ability to warm up the interior of the vehicle without use of electric heaters
Describe a water pump.
Usually driven by the timing belt or a drive belt. The water pump circulates coolant through the cooling system.
Describe the radiator.
An engine cooling device in a motor vehicle consisting of a bank of thin tubes in which circulating fluid is cooled by the surrounding air.
Describe the function of an electric cooling fan.
Pushes air through the radiator to aid in cooling at lower speeds or when idling.
Describe the upper radiator house.
Connects the radiator to the thermostat housing. Usually from a rubber impregnated reinforced cord.
Describe the lower radiator hose.
Connects the water pump to the radiator. Most lower hoses have a spring inside, to prevent the hose from collapsing due to suction created by the water pump.
Describe the heater core.
Warm coolant passes through the heater core to provide heat to the cabin of the vehicle.
Describe the thermostat.
Used in the cooling system to control the flow of coolant between the cylinder block and radiator. Helps warm the engine faster and maintain a proper operating temperature.
Describe the coolant recovery tank.
Collects the expanding coolant that is heated by the engine and recycles it back into the coolant system once it loses enough heat.
Describe the coolant temperature sensor.
Used to measure the temperature of the engine coolant. This info is then used by the engine computer for the fuel infection system and to know he to turn on the coolant fan and to aid in adjusting fuel volume.
Describe the radiator cap.
A pressure sealed cap located on top of the radiator. It allows the cooling system to operate under pressure (12-15psi).
When coolant is under pressure the boiling point increases how much?
Roughly 2degree F per 1 psi
Describe the water pump impeller.
Creates suction and pressure to move coolant through the system.
Describe the water pump shaft.
Connects the impeller to the hub
Describe the water pump bearings.
Allows the shaft to turn freely
Describe the water pump hub.
Provides mounting for cooling fan or pulley
Describe the water pump housing
Aluminum or metal housing that holds all the parts
Describe the water pump gasket
Mounts between water pump and engine block to prevent leaks.
What is coolant a mixture of?
Distilled water and antifreeze
What are the benefits of antifreeze in your coolant?
Prevents coolant from freezing in the winter and it also helps increase the boiling point of the coolant.
___________ helps prevent corrosion and rust from forming inside your engine.
Antifreeze
What are the types of radiators?
Cross flow, down flow, transmission oil cooler, heater core.
Describe a cross flow radiator.
Coolant tank on both sides, core tubes run horizontal, the coolant flows from one side to the other.
Describe a down flow radiator.
Coolants tanks are at the top and bottom, core tubes run vertically and the coolant runs from the top to the bottom.
Describe a transmission oil cooler.
An extra tank integrated into the radiator or a separate device placed in front of the radiator to cool transmission fluid.
Describe a flex fan.
During high speed operation, fan blades will flex straight. During slow speed operation fan blades return are able to move the air through the radiator.
Describe a fluid coupled fan (fan clutch).
Also called clutch or slip fins fluid in the fan will cause it to stop spinning at higher speeds.
Describe a thermostatic fan.
A temperature sensor activates a magnet in the fan to turn on the fan when it is needed.
Describe a electric fan.
Equipped on all FWD vehicles and some RWD vehicles. An electric motor is activated by a temperature sensor when the thermostat is open or the AC is in use.
What are cooling fans used for?
Cooling fins are required to keep the proper operating temperature while the vehicle is not in motion. While in use cooling fans can rob power and cause increased fuel consumption.
Where is a thermostat located?
At the coolant exit area of an engine
When will the thermostat be closed, and what happens to the coolant?
The coolant is cold.
with the thermostat closed the coolant will circulate through the engine heater core but not through the radiator.
What happens when the thermostat is open.
Engine warms, thermostat will open, coolant will then be able to flow through to the radiator.
What are signs of a faulty thermostat?
Thermostat is either stuck open or closed
What happens when the thermostat is stuck closed?
Overheating, rapid temperature change, leaking around the thermostat housing.
What happens when the thermostat is stuck open?
Extended warm up times, low heat, engine not reaching operating temperature, poor fuel economy.
What is a simple test that can be done to see if a thermostat is stuck open?
After running the engine for 1-2 mins feel the upper and lower radiator hoses. If Both hoses are warming up at an even rate.
How to tell if a thermostat is working correctly?
The engine temperature is below 180 F, the upper rad hose should feel hot and the lower rad house should feel significantly cooler.
An engine overheating can cause?
Engine damage/failure, engine seizing, coolant boiling and creating cracks, poor lubrications, and poor fuel economy.
An engine running cold can cause?
Excessive wear and tear on parts, poor combustion, poor fuel economy, higher exhaust emissions, and oil contamination.
