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Vehicle Cooling Systems
car engine featuring radiator and air filter

Learn why your car needs a cooling system


The function of the engine's cooling system is to remove excess heat from the engine, to keep the engine operating at the most efficient temperature, and to allow the engine to reach its ideal operating temperature in the shortest time possible.


In an ideal world, the cooling system keeps the engine running at its most efficient temperature no matter what the operating conditions are.


As petrol is burned in the engine, about one-third of the energy in the fuel is converted into power. Another third goes out the exhaust pipe unused, and the remaining third becomes heat energy.


A cooling system of some kind is necessary in any internal combustion engine. 


If no cooling system was provided, parts would melt from the heat of the burning petrol, and the pistons would expand so much they could not move in the cylinders.


The cooling system of a water-cooled engine consists of:


the engine's water jacket


water pump

radiator and radiator cap

cooling fan (electric or belt-driven)


heater core

expansion (overflow) tank


Burning of fuel in an engine produces very large amounts of heat and pressure; temperatures can reach up to 4,000 degrees F. when the air/petrol mix is in certain proportions correctly.


Under normal operating conditions the temperature is about 2,000 degrees F. The cooling system removes around 1/3 of all the heat that is produced in the engine combustion chamber.


The exhaust system also takes away much of the heat, but parts of the engine, such as the cylinder walls, pistons, and cylinder head, absorb large amounts of the heat. If a part of the engine gets too hot, the oil film will burn away and thus fail to protect it. This lack of lubrication can quickly destroy a car engine.


On the other side, if an engine runs at too low a temperature, it loses efficiency, the oil starts to get dirty (adding wear and reducing power output), deposits form, and fuel mileage is poor, not to mention poor exhaust emissions! For these reasons, the cooling system only comes into action when the engine has heated up to its optimal temperature.


Type of Car Engine Cooling System


There are two types of cooling systems; liquid cooling and air cooling. Most auto engines are cooled by the liquid type; air cooling is used more frequently for aircraft, motorcycles and lawnmowers.


Liquid Cooled Engines


Liquid cooled engines have passages for the liquid, or coolant, through the cylinder block and head. The coolant has to have indirect contact with such engine parts as the combustion chamber, the cylinder walls, and the valve seats and guides. Running through the passages in the engine heats the coolant (it absorbs the heat from the engine parts), and going through the radiator cools it. After getting "cool" again in the radiator, the coolant comes back through the engine. This business continues as long as the engine is running, with the coolant absorbing and removing the engine's heat, and the radiator cooling the coolant.


A cooling system pressure tester is used to check the pressure in the cooling system, which allows your TLC Autocentres technician to determine if the system has any slow leaks. The leak can then be found and fixed before it causes a major problem.


Read about the importance of antifreeze in your vehicle's cooling system on the next page.



Antifreeze Reminder Service info



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Free Vehicle Coolant Check info



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Anti-freeze Change info

from £35.00


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