The cylinder head gasket seals combustion pressure, coolant, and oil between the cylinder head and the engine block. Most head gaskets today fall into two broad designs: multi-layer steel (MLS) and composite. Each is engineered for different engine designs, so the right choice depends on the application.
Composite Head Gaskets
Composite gaskets use facing materials bonded to a metal core, often with steel fire rings around the cylinder bores. The facing material can conform to small surface imperfections, which makes composite gaskets common on many older engines, especially those with cast-iron heads and blocks.
MLS Head Gaskets
MLS gaskets are made from several thin layers of embossed steel, usually with a coating on the outer layers. They hold up well to high cylinder pressures and to the movement that occurs between an aluminum cylinder head and the block as they expand at different rates. Many modern engines are designed to use MLS gaskets from the factory.
Surface Finish Matters
MLS gaskets generally require smoother, flatter sealing surfaces than composite gaskets. Before installing any head gasket, check the head and block decks for flatness and confirm the surface finish meets the requirement for the gasket being used. A surface that is too rough or warped can cause a leak regardless of gasket quality.
Which One Should You Use?
Use the gasket type designed for the specific engine and application. Do not substitute one design for the other unless the gasket manufacturer specifically supports it. Follow the installation instructions supplied with the gasket, including whether any sealant is used, the head bolt torque sequence, and whether new head bolts are required.
Evergreen Head Gasket Sets
Evergreen cylinder head gasket sets are configured by engine application, and head gasket construction varies by part number. Use the Evergreen eCatalog to identify the right set for your engine.
