Diagnosis And Testing: DEAERATION
As air is removed from the cooling system, it gathers in the pressurized coolant bottle. When this pressure exceeds the maximum pressure specification on the pressure cap, it is released into the atmosphere through the pressure valve located in the coolant bottle cap.
NOTE:
Deaeration does not occur in the engine cooling system at engine idle, higher engine speeds are required. Normal driving will deaerate the engine cooling system.
To effectively deaerate the system, multiple thermal cycles of the system may be required.