Gasket that sits between the engine block and cylinder head(s) in an internal combustion engine
Head gasket (in dark gray with a red border) sitting on top of an inline-four engine block. When installed, the four large holes will align with the cylinders.
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.
^Bickford, John H. (1997). Gaskets and Gasketed Joints. CRC Press. p. 57. ISBN0-8247-9877-5.