Radiator Cap: Description and Operation

1. Coolant expands as the temperature and pressure rise in the system.
2. When the limiting system working pressure is reached, the pressure relief valve in the radiator cap (8100) is lifted from its seat and allows coolant to flow through the radiator filler neck and the radiator overflow hose (8075) into the radiator coolant recovery reservoir (8A080).
3. When the system temperature and pressure drop, the coolant contracts in volume and the pressure in the radiator (8005) is reduced.
4. The coolant in the radiator coolant recovery reservoir will then flow back into the radiator through the vacuum relief in the radiator cap. The radiator cap has a rubber seal on the underside to prevent leakage.