Cooling System Aeration

Cooling System Aeration

Low coolant level in a cross flow radiator will equalize in both tanks with engine off. With engine at running and at operating temperature, the high pressure inlet tank runs full and the low pressure outlet tank drops, resulting in cooling system aeration. Aeration will draw air into the water pump resulting in the following:

• High reading shown on the temperature gauge.

• Loss of coolant flow through the heater core.

• Corrosion in the cooling system.

• Water pump seal may run dry, increasing the risk of premature seal failure.

• Combustion gas leaks into the coolant can also cause the above problems.

• Deaeration does not occur at engine idle, higher engine speeds are required. Normal driving will deaerate cooling system.

Air can only be removed from the system by gathering under the pressure cap. On the next heat up it will be pushed past the pressure cap into the coolant recovery bottle by thermal expansion of the coolant. It then escapes to the atmosphere in the coolant recovery bottle and is replaced with coolant on cool down.

To effectively deaerate the system, multiple thermal cycles of the system may be required.