Radiator Cap Pressure

To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid & steam under pressure if radiator cap or surge tank cap is removed while the engine & radiator are still hot.

The surge tank cap maintains proper pressure, protects the system from high pressure by opening a pressure valve, and protects the coolant hoses from collapsing because of a vacuum.