Full Gasket Set Fit Chevrolet GMC Buick Cadillac 4.8 & 5.3L OHV C, M, P, T. The head gasket is the key component of the engine. It is compressed between the engine block and the cylinder head. The head gasket seals in the internal combustion process to make sure maximum compression is achieved and also keeps coolant and oil from mixing together as the two fluids travel from the engine block to the cylinder head. Head gasket set is used for upper engine repair. It can be combined with a conversion gasket set / lower gasket set to form a full gasket set for the entire engine. Time will come that your gaskets and seals will leak or blow. Always remember, when your head gasket or seals fail, a replacement gaskets and seals should immediately be installed. Be sure to have your engine gaskets replace with aftermarket replacement full gasket set as soon as it starts to give you trouble.