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The radiator cap is a part of the radiator equipment in cars where it is used to close the water coolant or the radiator itself. It looks simple and the function may be to essentially cover the cap but it is more than that. The radiator cap plays a role in troubleshooting problems in the engine. It also helps in maintaining the fluid pressure inside the radiator or the coolant system so that there is enough water circulation that flows into the tube.


When buying a radiator cap you should be familiar with its construction. There is a dish diaphragm made of spring that helps in sealing the cap against radiator fillers. There is also a big spring which essentially helps in maintaining the pressure on the radiator. The big springs holds the sealing gasket on the lower end and the pressure valve. There is also a vacuum valve that is located at the bottom of the cap which allows the air or the coolant to go back to the radiator when you turn off the engine or when the engine is not in use. A low sealing gasket helps in keeping the coolant stay where it is designed to stay. This is an important part of the radiator cap and it should be tightly sealed so that the coolant cannot escape which is a major cause of overheating.

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