The gasket set consists of a steel gasket
consisting of 5 layers. In the centre is a steel shim with swaged on
fire rings - which appears to be very similar to the original gasket
designs. This, like the original gasket is encased by two steel layers
- rather like a sandwich. 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. These layers are there to help prevent any
coolant leakage failures.
The
other interesting feature of the new gasket set is the so-called 'sixth
layer' or shim. The shim, as shown opposite (left), 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 to the gasket
face opposite) and the lower side is coated with an inert matt-grey
treatment - and it is this side of the shim that comes into contact
with the upper surface of the MLS gasket.
The shim appears to provide 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.
Secondly, and the potential advantage of
this system over the original gasket design, 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 gone soft, or where the casting has an
imperfection close to the combustion chamber; the shim will help
prevent the liners hammering into the head.
