The expansion tank is connected with one hose to the radiator and the other hose to the cooling system. In the process of movement, the coolant expands. A portion of the expanded coolant exits the radiator and engine into the expansion tank. Air that has entered the radiator and engine is also forced into the expansion tank.
When the engine is stopped, the coolant cools and contracts. The displaced liquid returns back to the radiator and engine. This helps to keep the liquid level at the required level at all times and improves the quality of cooling.
Ensure the fluid level is between the MIN and MAX marks on the expansion tank when the system is cold.
Expansion tank cap check
1. Pressurize the cap from 120 to 160 kPa.
2. Wait 10 s and check the residual pressure in the system using a manometer.
If the pressure measured by the cooling system pressure tester falls below 80 kPa, replace the expansion tank cap.