What does the top of the radiator cap do?
What does the top of the radiator cap do? The cap acts as a pressure relief valve. Too much pressure can cause damage, while not enough pressure can cause the engine to overheat. The top portion of the radiator cap will list the pressure rating. Always use a cap of the correct pressure for your cooling system. Where can I find the pressure on my radiator? Check the pressure on the cap with a radiator cap pressure tester. You can find new pressure caps for your radiator in the local auto supply store. Also, online retailers can provide caps but...