Gaskets & Seals

Is your engine sweating oil at a joint, or does the cylinder head need to come off during a project? Gaskets and seals keep oil, coolant, combustion gases and compression where they belong between the parts of the engine, exhaust and drivetrain. The category covers everything from oil seals and O-rings to complete gasket kits and gasket material for both daily drivers and tuned projects.

What gaskets and seals do

A gasket fills the small irregularities between two surfaces so the joint stays sealed under pressure and heat. Among engine gaskets and seals you will find, for example, head gaskets, intake manifold gasket kits, oil filter housing gaskets and timing belt cover seals. Rotating shafts are typically sealed with oil seals, while O-rings are used in fittings and housings, for example. For the drivetrain there are separate groups for gearbox, differential and transfer case.

How to choose the right gasket

Start with the engine code or the part number of the original part – fitment depends on engine and model year, not just the car model. Then consider:

• Thickness: A head gasket affects the compression ratio, so the thickness should be chosen based on the engine build and any decking or resurfacing of the cylinder head or block.
• Bore: With larger pistons, the gasket bore must match the new cylinder diameter, e.g. 83.5 mm on a Cometic head gasket for the Audi 2.5 TFSI.
• Material: Multi-layer steel (MLS) gaskets can typically handle higher cylinder pressure and boost than soft gaskets, but often require flat surfaces with the correct surface finish.
• Single part or kit: If several joints need to be opened, a complete kit, such as the Fel-Pro intake manifold kits for the Ford Mustang and Dodge Challenger, can ensure you are not missing a single gasket.

Exhaust, installation and gasket material

Exhaust gaskets sit at the exhaust manifold, headers and flange joints, where heat and vibration put them under heavy stress. New headers may require different gaskets than the originals, so check the flange shape. When installing: clean the surfaces thoroughly, check them for warping, and tighten to the manufacturer's torque and sequence. If no ready-made gasket is available, you can cut your own from gasket material sheets, e.g. for covers and low-pressure flanges.

Brands and engines in the category

Brands include Cometic Gasket, Fel-Pro, Victor Reinz, Vertex Pistons and Wiseco. The range includes parts for engines such as the Ford 302/351W and 4.6/5.4L V8, Nissan RB20/RB26DETT and Audi 2.5 TFSI, as well as a few motorcycle and ATV engines such as the Yamaha YFZ450R.

Frequently asked questions

Can I reuse an old gasket?

It is generally not recommended. A gasket is compressed and conforms to the surfaces on first installation, so it rarely seals as well a second time. This applies especially to head and exhaust gaskets, where pressure and heat are highest.

How do I choose the thickness of a head gasket?

The thickness affects the compression ratio and the clearance between piston and cylinder head. If the head or block has been resurfaced, or different pistons have been fitted, the thickness should be calculated from the actual measurements rather than just the original spec.

Should I use gasket sealant with a new gasket?

It depends on the gasket and the manufacturer's instructions. Many multi-layer steel and coated gaskets should be installed dry, while certain joints, e.g. where two parts meet at a corner, may require a small amount of sealant.

Why is a new gasket leaking?

Typical causes are warped or dirty surfaces, incorrect torque or tightening sequence, reused bolts or a gasket that does not fit the specific engine. Check the surfaces and the engine code before you install a new one.