14. Gaskets and Seals

An important challenge in engine design is that of providing leak-free joints at each of the component mating surfaces exposed to one or more of the working fluids. Minimizing the number and complexity of joints is one design goal. Another is that of providing durable, effective seals at each of the remaining joints. The working fluids include fuel, lubricant, coolant, intake air, and combustion products. Some joints must maintain separation between two or more of the engine’s working fluids, while others seal one of the working fluids from the atmosphere. Some joints are stationary, while others include the need for one component to move relative to the other. These moving joints include the interface between the pistons and cylinder walls, those between the valve stems and guides, and those associated with spinning shafts protruding from the engine (the crankshaft and the water pump are examples). A categorization of seal types is presented in Fig. 14.1. Piston rings and valve stem seals will be covered in Chaps. 15 and 17 respectively.