Stainless steel pressure cap for header tank or radiator
The radiator cap pressure valve consists of a spring-loaded disc that contacts the filler neck. The spring pushes the valve onto the neck to form a seal. Under pressure, the boiling point of water increases. If the engine overheats and the pressure exceeds the cap rating, the pressure valve opens. Excess pressure forces coolant out of the overflow tube and into a reservoir or onto the ground. This prevents high pressure from rupturing the radiator, gaskets, seals, or hoses. CAUTION - Always remove the radiator cap slowly and carefully. Removing the radiator cap from a hot pressurised system can cause serious burns from escaping steam and coolant.