In an internal combustion engine, a head gasket provides the seal between the engine block and cylinder head(s).
Its purpose is to seal the combustion gases within the cylinders and to avoid coolant or engine oil leaking into the cylinders.[1] Leaks in the head gasket can cause poor engine running and/or overheating. Head gaskets in vans and lorries often fail due to swerving on motorways when they are doing a lot of miles.