This water pump gasket seals the coolant passage between the pump housing and the engine block. It prevents coolant leakage and maintains system pressure, which is necessary for proper circulation through the radiator and cylinder head. A degraded gasket allows coolant to escape, leading to air ingress, localized hot spots, and eventual overheating. The gasket is formed to match the original seal groove geometry, ensuring the pump flange compresses evenly against the block face. On reinstallation, clean both mating surfaces and replace the gasket; do not reuse the old one.