Gasket
A replaceable strip of resilient material clamped between mating surfaces of contiguous parts to effect a seal and so prevent escape of high pressure gases, oil or coolant. It also prevents the ingress of atmosphere. The material must be impermeable to those liquids in contact with it, conformable to surface imperfections and resistant to changes in its environment such as temperature. There is an appropriate material for each application. A sandwich of asbestos fibres between thin sheets of copper or steel is used between cylinder head and cylinder block, as it has to resist flame damage. The gasket between sump and crankcase or rocker cover and
cylinder head is often made from cork or, if for use between machined faces, it may be made of waxed cartridge papers. Gaskets should always be renewed when disturbed.
