Payen MLS Head Gasket

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Payen Multi-Layered Steel (MLS) Gasket.

The new gasket set consists of a steel gasket consisting of 5 layers with a steel shim and swaged fire rings, encased by two steel layers.

In contrast to the older gasket design, rather than using bonded-on 'elastomeric' butyl rings to contain the coolant jacket and oil drain spaces, the gasket has an additional two steel layers on either side of the gasket with swaged / raised areas to provide the coolant / oil void sealing.

The layers prevent coolant leakage failures; which was frequently due to peel-away of the butyl rings.

The other interesting feature of the new gasket set is, the 'sixth layer' or shim. The shim, as pictured is inserted between the MLS gasket and the cylinder head, black surface uppermost.

The shim is coated on both sides; on the upper side (the head-facing side) with a dry sealant (it has the same black, glossy appearance as the gasket face opposite) and the lower side is coated with an inert matt-grey treatment. It is this side of the shim that comes into contact with the upper surface of the MLS gasket.

The shim provides two main roles. Firstly, it prevents the fire rings on the gasket digging into the cylinder head. When the head is torqued down, the fire rings are crushed between the liners and the cylinder head.

The shim prevents the ring from digging into the head and enables the 'ring' to roll over the gasket layer in the manner in which it was designed.

The advantage of this system over the original gasket design is that it acts as a protective layer to the cylinder head; a layer that comes into its own if the condition of the head is less than perfect.

Examples of this is where the cylinder head has softened due to excess heat, or where the casting has an imperfection close to the combustion chamber; the shim will help prevent the liners marking the head and aid in the sealing of the fire walls.

Fitting the MLS Gasket with the shim provided will lower the compression ratio by approximately 0.4 from standard.