This gasket seals the joint between the water manifold and the engine block, preventing coolant leakage at the connection point. It sits between the manifold flange and the mating surface on the cylinder head or block, where it compresses under clamping load to form a leak-resistant barrier. A degraded gasket allows coolant to escape, leading to gradual pressure loss and potential overheating. On reinstallation, clean both sealing surfaces thoroughly and tighten the manifold bolts to the specified torque sequence to ensure even compression.