As the engine of your GMC is running, oil is used to protect it against damaging friction and coolant is used to maintain the correct operating temperature. The GMC head gasket is one of the many seals used to keep these fluids separate from each other, so that they can protect the engine adequately. It sits between the engine block and the cylinder head on each side of the engine. In addition to keeping the fluids separate, the GMC head gasket also provides a seal that separates each of the combustion chambers. Before the mixture of air and fuel is ignited in the engine, it is compressed to allow the resulting explosion to produce a greater amount of power, as the mixture expands to its normal volume. As the GMC head gasket ages, the rubber it is made from will begin to harden, and eventually a leak will form. If the leak is between two cylinders, the engine will begin to run less efficiently, because the proper amount of compression cannot be maintained. If the leaking GMC head gasket allows the coolant and the oil to mix, the engine will no longer be properly protected from either heat or friction. Fortunately, our online catalog will have the proper replacement for almost any engine, at a great price. Our GMC head gasket is made to meet the specifications of the original unit, ensuring that it will last equally as long. The GMC head gasket for your vehicle may be ordered over the phone, with a toll-free call to our sales department, or through our web site, using our secure online ordering system.