Functioning as a pressure release valve, dumping hot fluid and re-introducing cooled fluid, the radiator cap maintains the optimum pressure and temperature within the cooling system. However, a malfunctioning radiator cap can result in poor coolant efficiency and eventually severe engine damage. Pressure imbalance can cause the overflow chamber to run dry and coolant to vaporise upon release, leading to localised and/or general overheating of the engine. If left unchecked this can result in blown gaskets and cracked cylinders. Defective radiator caps should be replaced immediately to avoid further damage. Our extensive selection includes quality, affordable caps for all makes and models of engine.