The expansion tank is connected to the radiator with one hose and to the cooling system with the other hose. During movement, the coolant expands. A portion of the expanded coolant leaves the radiator and engine into the expansion tank. Air that has entered the radiator and engine is also forced out into the expansion tank.
After the engine is stopped, the coolant cools and contracts. The displaced liquid returns to the radiator and engine. This helps maintain the liquid level at the required level at all times and improves the cooling quality.
Ensure the fluid level is between the MIN and MAX marks on the expansion tank when the system is cold.
Checking the expansion tank cap
1. Apply pressure to the lid from 120 to 160 kPa.
2. Wait 10 seconds and check the residual pressure in the system using a pressure gauge.
If the pressure recorded by the cooling system pressure tester drops below 80 kPa, replace the expansion tank cap.