FixVault

Radiator Pressure Cap-Description

WARNING: This page is about a different car, the 2007 Dodge Sprinter. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Radiator Pressure Cap - Typical
GC0036955Courtesy of CHRYSLER LLC
1 - FILLER NECK SEAL
2 - VACUUM VENT VALVE
3 - PRESSURE RATING
4 - PRESSURE VALVE

All vehicles are equipped with a pressure cap. This cap releases pressure at some point within a range of 124-145 kPa (18-21 psi). 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 124-145 kPa (18-21 psi).

A rubber gasket seals the radiator filler neck. This is done to maintain vacuum during coolant cool-down and to prevent leakage when system is under pressure.