Gaskets & Seals

Engine Gaskets and Seals for Every Rebuild

Every engine rebuild needs new engine gaskets and seals, because used parts have already been compressed, heat-cycled and soaked in oil. Start with the head gaskets, which seal combustion pressure, coolant and oil between the block and cylinder heads. Intake manifold gaskets seal the intake ports and, on many V8s, the coolant passages at each end of the manifold.

Down low, the oil pan gasket and rear main seal keep oil inside the crankcase. A leaking rear main seal is a common source of drips at the bellhousing, and replacing it usually means pulling the transmission. Valve stem seals control how much oil reaches the valve guides, so worn ones can cause blue smoke on startup.

If you're doing a full overhaul, a complete gasket set saves you from tracking down each part separately. If you're fixing a single leak, buy the individual gasket and inspect the mating surfaces before you install it. Clean, flat flanges matter as much as the gasket itself.

Exhaust, Turbo and Transmission Gaskets

Outside the engine's core, you'll need gaskets that handle exhaust heat, boost pressure and transmission fluid. Exhaust gaskets and seals cover header flanges, exhaust manifolds and collectors. Match the gasket's port shape and size to your cylinder head and header flange, or you risk leaks and burned gasket edges.

Our exhaust gasket sizing and installation guide walks you through choosing the right size and installing it. Forced-induction engines put extra heat and pressure on every joint between the turbo or blower and the engine. Turbocharger and supercharger gaskets and seals are built for those flanges and blower-to-manifold connections.

On the drivetrain side, transmission gaskets and seals include pan gaskets, front pump seals and output shaft seals. A leaking pan gasket or output shaft seal can drop fluid levels between services. It's worth replacing both whenever you have the transmission apart.

How to Choose a Head Gasket

Choose a head gasket by matching its construction, bore size and compressed thickness to your engine and build. Multi-layer steel (MLS) head gaskets stack several thin steel layers, usually with a rubber-like coating. They handle high cylinder pressure from boost, nitrous or high compression, but they need a smooth, flat deck and head surface.

Composite head gaskets use a facing material over a steel core. They're more forgiving of minor surface imperfections on stock or mild rebuilds. Next, check the bore size, which should be slightly larger than your cylinder bore so the gasket edge doesn't hang into the chamber.

Compressed thickness is the gasket's thickness after the heads are torqued. It changes your compression ratio and piston-to-head clearance, so a thicker gasket lowers compression and a thinner one raises it. Before you order, read up on what a cylinder head does. You can also browse our engine and components tech articles for more build-planning help.

Gasket Materials, O-Rings and Grommets

When a pre-cut gasket isn't available, or you need to seal a line, fitting or wire pass-through, these parts fill the gap. Here's what each one does:

• Bulk gasket materials come in sheets you can cut to fit custom flanges, covers and fabrication work.
• O-rings seal fittings, filter housings, fuel components and other round joints under pressure.
• Grommets protect wiring, hoses and sensors where they pass through sheet metal or mount to the engine.
• Sealers and adhesives, including RTV, seal corners, uneven surfaces and joints that don't use a gasket.

Pick a material rated for the fluid and temperature it'll see. Cork and rubber suit low-pressure covers and pans, while fiber and graphite materials handle more heat. For O-rings, confirm the size and check that the material is compatible with the fuel or oil it'll touch.

Gaskets and Seals From Brands Builders Trust

JEGS stocks gaskets and seals from manufacturers engine builders already know, so you can stay with a brand you trust. Fel-Pro covers a wide range, including PermaTorque composite head gaskets, PrintoSeal big-block Chevy intake gaskets and PermaDryPlus oil pan gaskets. It also offers rear main seals for 1959-1989 GM and 1969-1984 Ford 5.8L and 6.6L engines, plus marine gasket sets.

Moroso offers race-quality oil pan gaskets for Ford 460 and big-block Chevy Mark 4 engines. For valvetrain work, Melling makes valve stem oil seal sets for GM LS engines. Edelbrock offers valve stem seals for 11/32" stems.

On the exhaust side, Hedman supplies 3" 3-bolt collector flange gaskets for header installs. Earl's Stat-O-Seal washers, including 7/16" ID sizes, seal bolts and plumbing connections. Before you order, check each product's fitment details against your engine, year and application so the part seals the first time.