GM Genuine Parts Engine Coolant Crossover Pipe Gaskets are designed, engineered, and tested to rigorous standards, and are backed by General Motors. These gaskets are used to seal the interface between the coolant crossover pipe and the cylinder heads, engine block, or another engine component. The gasket may be made of fiber or a rubberized composite material that provides a liquid-tight connection. The gasket helps keep the engine coolant in and keeps air out. GM Genuine Parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE).