Cooling System DEAERATION

As the engine operates, any air trapped in the cooling system gathers under the radiator cap. The next time the engine is operated, thermal expansion of the coolant will push any trapped air past the radiator cap and into the coolant reserve/overflow tank. Here it escapes to the atmosphere into the tank. When the engine cools down, the coolant will be drawn from the reserve/overflow tank into the radiator to replace any removed air.