How does your car’s cooling system work?

The cooling system in your car is an integral part of how it functions, and it keeps your engine from overheating as it runs. It accomplishes this task by using a variety of parts to move coolant throughout parts of the engine, which absorbs heat energy and transports it away from the vehicle. If you’re driving down the highway, your car has to remove enough heat at any given time to heat two average-sized houses. Additionally, the cooling system allows your car to heat up rapidly during winter, and keeps it at a constant temperature of about 200 degrees Fahrenheit once it warms.

The cooling cycle starts at the pump, which is responsible for sending coolant into the engine block. The fluid passes around the cylinders, absorbing heat from the engine, and leaves near a thermostat that measures surrounding temperature. If the fluid is not too hot, the coolant returns to the pump, but otherwise it heads to the radiator to shed excess heat before going back to the pump.

For automatic transmission cars, there is another circuit that pumps transmission oil into a separate space in the radiator as well. In some cars, there is a fan in front of the radiator, not only to help the radiator lose heat more quickly, but also to provide an extra element of cooling for the engine.

The coolant used by your car has some very unique properties. It must be able to remain a liquid under extremely cold or hot temperatures, as well as be able to absorb plenty of heat. Water is great at absorbing and circulating heat, but has too low of a freezing point to be a coolant on its own. Therefore, it is mixed with ethylene glycol to create a solution that can handle moving the heat from your engine, while being able to stay liquid under any condition. The high pressure the solution is under due to the pump, which operates whenever the engine is running, also helps ensure that the water in the solution does not freeze in cold weather.

—Seth Berger

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