Radiator Cap: Description and Operation

DESCRIPTION








The cooling system pressure cap attaches to the coolant bottle. The cap construction includes, a plastic swivel top, rubber seals and retainer, a main spring, and a spring loaded valve.

OPERATION
The pressure cap allows the cooling system to operate at higher than atmospheric pressure, which raises the coolant boiling point. This pressure allows for increased radiator-cooling capacity. The pressure cap will release cooling system pressure at some point within a range of 117 kPa ± 7 kPa (17 psi ± 1 psi).
A spring-loaded vent valve in the center of the cap allows the system to pressurize and Repressurize without creating a vacuum. If the valve is stuck open, coolant will escape to the overflow hose. A gasket seals the cap to the top of the filler neck.