The installation of gaskets is one of the most important aspects of rebuilding an engine. Gaskets provide a seal between mating surfaces so oil, coolant, vacuum and pressure don't leak. As long as all the gaskets are installed properly, everything should be fine, and the engine shouldn't leak. But, as every rebuilder or technician knows, even a small leak can create an expensive warranty problem for you and your customer.

When gaskets are installed, a good seal depends on proper loading and torque. This is especially critical with head gaskets because of the high pressures they must withstand when the engine is running.

The amount of torque that's applied to each head bolt, as well as the order in which the bolts are tightened, determines how the clamping force is distributed across the surface of the gasket. If one area of the gasket is under high clamping force while another area is not, it may allow the gasket to leak at the weakly clamped point. So all the head bolts must be tightened in a specified sequence and torqued to a specified value to ensure the best possible seal.

With pan and cover gaskets, overtightening can crush the gasket causing it to slip or split. Many gaskets have grommets that control the amount of crush, and others have metal or plastic carriers that provide added support and reinforcement. Using an inch-pound torque wrench is recommended on the fasteners for these types of gaskets to mak...