Cap, Radiator: 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.

A spring-loaded vent valve in the center of the cap allows the system to pressurize and depressurize 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.