Cap, Radiator: Description
All cooling systems are equipped with a pressure cap. The pressure cap is located on top of the pressurized coolant bottle. The cap releases pressure at some point within a range of 21 psi (145 kPa) (1). The pressure relief point (in pounds) is printed on top of the cap.
The cooling system will operate at pressures slightly above atmospheric pressure. This results in a higher coolant boiling point allowing increased radiator cooling capacity. The cap contains a spring-loaded pressure relief valve. This valve opens when system pressure reaches the release range of 21 psi (145 kPa).
Two O-ring gaskets seal the pressurized coolant bottle. This is done to maintain vacuum during coolant cool-down and to prevent leakage when system is under pressure.