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Engine Cooling System

How the car engine cooling system works

A car’s engine operates most efficiently at high temperatures, emitting less pollution and keeping its components in condition. However, as a car burns fuel, it produces surplus heat. The job of the car’s cooling system is to allow the engine to attain its maximum operating design temperature, and maintain this temperature during its operation and dissipate the excess heat.

The cooling system has various components such as the radiator, pressure cap, water pump fan, pump, thermostat, hoses and overflow tank. The pump sends cooling fluid to the engine where it absorbs the engine’s heat.

Once passing through the engine, it flows over a thermostat. If the cooling fluid is below the maximum temperature, the thermostat stays closed and the cooling fluid is re-routed back to the pump.
However, if the cooling fluid is overheated, the thermostat’s valve opens, routing the fluid through the radiator. This cools the fluid by releasing its heat into the air before returning to the water pump only to be circulated again throughout the cooling system and various components.

Cars can have a liquid cooling system or an air cooling system, although most modern cars are liquid-cooled. With a cooling system based on liquid, fluid contained in various linked pipes pass through the engine, absorbing heat while cooling the engine. If the fluid is overheated, it is routed through the radiator, which acts as a heat exchanger, releasing the surplus heat to the air.
On the other hand, a cooling system based on air has aluminum fins surrounding the engine. When the engine is overheating, fans blow air over the fins to conduct the heat away from the engine’s cylinder, cooling it down.
A properly functioning cooling system, which circulates antifreeze/coolant and dissipates the heat away from the engine, is necessary to prevent a vehicle’s temperature rising too high and causing damage.

Vehicles have five principal components in their cooling system.

  • Radiator – Has a set of tubes called the “core” through which the coolant flows. Surrounded by cooling fins. As air passes through the fins, the coolant releases its heat to the fins, dissipating the heat.
  • Radiator cap – The cap is designed to seal the system to a specific pressure.
  • Radiator hoses – The coolant flows from the radiator to the engine through a series of hoses.
  • Thermostat – The engine thermostat keeps the engine at the operating temperature.
  • Water pump – This is the heart of the engine’s cooling system. It pumps coolant through the cooling system and into the engine block.

Engine overheating can come from a variety of sources. With combustion temperatures reaching 1093° C and higher, there is a lot of heat to dissipate. If the engine is running hotter than normal, either shortly after starting or over time, have the cooling system checked.

Check to see if any green, orange or yellow fluid has accumulated and a puddle of fluid is visible under the vehicle when stationary. If this is the case, you are probably losing coolant, which could indicate a leak in the system. Loose or improperly adjusted belts and hoses, leaking gaskets and even mechanical engine damage due to extended or high engine life could be the cause. AutoZone has the knowledge and expertise to check your coolant system.