The exhaust manifold is a cast, branched tubular alloy unit, which is attached to the cylinder head, the shape corresponds with the position of the exhaust valves in the head. The exhaust emissions from the engine pass through the manifold which connects to the exhaust pipe system. As the exhaust valves open within the head/s of the cylinder the fumes are forced into the manifold and into the exhaust system.

The exhaust manifold gasket, usually made of rubber or cork, functions to firmly seal the exhaust manifold to the cylinder head.

On a V configured engine there will be two cylinder heads and therefore two exhaust manifolds which are bolted to the side of the heads.  Sandwiched between the cylinder head, providing a secure seal between the cylinder head and the exhaust manifold is the exhaust manifold gasket .

The  reason for changing the exhaust manifold is usually due to leakage through a hole or crack caused by heat and corrosion. A new sealing gasket is required for replacement of the manifold. The exhaust manifold gasket can wear over time and will eventually need replacing. Shrunken, cracked or rotten exhaust manifold gaskets should be replaced as soon as possible.