This expansion tank stores coolant that has been heated and expanded by the engine, allowing the system to maintain a consistent pressure and fluid level. It is installed in the engine bay, connected to the radiator or the engine's coolant circuit via a hose. The tank provides a reservoir that captures overflow and returns it to the loop as the engine cools, preventing air from entering the system. A cracked or leaking tank causes gradual coolant loss, leading to overheating and potential engine damage. The manufacturer's part matches the original mounting points and hose connections, so no modifications are needed during replacement.