3.0L Diesel
This 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 18 psi (124 kPa). The pressure relief point (in pounds) is engraved 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 18 psi (124 kPa).
Two O-ring gasket seals the pressurized coolant bottle. This is done to maintain vacuum during coolant cool-down and to prevent leakage when system is under pressure.