Valve stem seals are sprung-lip seals pressfit over valve guides in internal combustion engines. The molded, radiused seal lip touches the valve stem, which is reciprocating within the valve guide. The magnitude of the lip radius meters (controls) the lubrication of the valve stem such that the stem receives neither too little nor too much oil. A stamping flange on the seal O.D. provides a seat for the valve spring to prevent damage to the surface of the valve seat area. A typical valve stem seal design is shown in Figure 204. Figure 205 shows this seal installed in an assembly.

“Because of the many ways in which shaft seals may be configured, they are common in a wide variety of automotive applications.”

Figure 204

Figure 205