Exhaust Manifold Gaskets

Is exhaust gas leaking at the manifold, or do you need new gaskets when fitting headers? In this category you will find gaskets and gasket sets that seal between the cylinder head and the exhaust manifold – for you who are fixing a leak or building a project.

What does an exhaust manifold gasket do?

The gasket seals the joint between the cylinder head and the manifold or headers, where temperature and thermal expansion are typically highest in the exhaust system. A leaking gasket can cause a ticking noise on cold start, a smell of exhaust gas in the engine bay and can affect the oxygen sensor readings. For joints further down the system, see exhaust flange gaskets, and for the turbo joints see turbo gaskets.

How to choose the right gasket

Several factors must match before the gasket will seal reliably:

• Engine: The sets are engine-specific, e.g. for GM Gen-3/4 small block V8, Gen-2 Hemi, Ford Coyote 5.0 and 6.7L Cummins diesel.
• Port size: The openings must match both the cylinder head ports and the manifold tubes. Some sets state the dimensions, e.g. the Fel-Pro set for Ford 260/289/302/351W with 1.42 x 1.62 inch ports.
• Material: Multi-layer steel (MLS) is available from BLOX Racing, for example. The right choice depends on the flatness of the surfaces, the heat load and whether the engine runs boost.
• Flange type: With a T4 manifold, the gasket must match whether the flange is divided or open.

Installation and maintenance

Clean off old gasket material, check that the surfaces are flat, and tighten the bolts to the manufacturer's torque and sequence. Some sets, e.g. the Ford Racing kit for the Mustang 5.0L Coyote, come with installation hardware. Brands in the category include Cometic Gasket, JBA, Gibson and QuadBoss, and you will find more seals under exhaust gaskets and seals.

Frequently asked questions

Can I reuse an old exhaust manifold gasket?

It is typically not recommended. The gasket settles during the first heat cycle and tightening, so a used gasket often seals less well. At the same time, check that the flanges are flat and free of cracks.

Why does the engine still tick after replacing the manifold gasket?

The noise can be caused by a warped manifold or header, a loose or broken bolt, or gasket ports that do not match the cylinder head. Check the flatness of the surfaces and tighten according to the manufacturer's instructions.

Do I need a different gasket when switching to headers?

It depends on the header's flange and tube diameter. Some headers require gaskets with larger or differently shaped ports, e.g. the BBK sets for Coyote and Hemi that are designed for headers.