Cooling system

Internal combustion engines have improved over the years but they are still about 30% efficient. The other 70%  is lost through heat, this heat is removed from the engine using the cooling system to prevent it from over heating and keeping it around 80 degrees Celsius The heat is removed by air flowing through the radiator. In the radiator/cooling system there is a mixture of water and antifreeze. The cooling systems job is not only to remove the heat from the engine but also to bring the engine to operating temperature as quickly as possible because the engine wears out more and creates more pollution when it is cold. The thermostat is used to bring the engine to operating temperature by blocking off the radiator and forcing the coolant to circulate around the block (where the heat is created). When the coolant reaches operating temperature the thermostat opens to allow the coolant to cool down through the radiator, then when it cools down the thermostat closes again. A fan is fitted to the engine or radiator to keep the air flowing through the radiator when the vehicle is stationery.

Experiment


Pressure testing


Pressure testing is used to check the cooling system for leaks by pressurizing the coolant with air. If there is a leak the pressure will go down over time (the gauge will go down)

Radiator

The radiator was visually checked for signs of corrosion or damage. The cap is also checked for damage and pressure tested.

Damaged radiator

Coolant testing (specific gravity)


The coolant is checked using a hydrometer. It indicates if there is enough antifreeze in the cooling system and what stat it is in.

Hoses


The hoses are visually checked for signs of wear like cracks

Thermostat


The thermostat is checked to see if it opens and closes at the right temperature by taking it out of the engine and placing it is a pot of water that is at the manufacturer's specified temperature.

Fan


The working condition of the fan is checked by bypassing the fan switch. If the fan does not go on there may be a fault with the relay, wires or the fan its self. The fan can be connected to power directly to see if it works. The switch can be checked by getting the engine up to operating temperature while the car is stationery.

Water pump and belts


The water pump is checked by removing its drive belts and turning it by hand, it should turn smoothly if it doesn't it will need to be replaced. The drive belts are checked for wear and that they are correctly adjusted.

Reflection


The cooling system is very important to ensure that the engine works correctly. If the engine over heats it could blow the head gasket or cause the engine to seize. If the thermostat stays closed the temperature will increases until the engine over heats as it does not allow the coolant to go to the radiator. If the thermostat stays open or opens at the wrong temperature it may result in the engine taking a long time to get to operating temperature or it may stay at a low temperature. If the fan does not work the car will over heat while stationery.