This exhaust manifold gasket seals the joint between the exhaust manifold and the cylinder head on the host engine. It prevents the escape of pressurized exhaust gases, which would otherwise cause a loss of back pressure, a drop in engine power, and an audible ticking or hissing sound. The gasket is compressed between the two metal faces during installation; a leak develops if the gasket material degrades from thermal cycling or if the mounting fasteners lose their clamp load. On reinstallation, clean both sealing surfaces thoroughly and tighten the manifold bolts to the specified torque in the correct sequence.