It is quite common for a groove to develop at the sealing lip at some point due to long-term use. As a result, the new oil seal no longer fits and seals properly. It is not strictly necessary to replace or repair the entire shaft. Take a closer look at the dimensions first. It may be possible to fit with a slightly narrower or wider oil seal next to the groove. Alternatively, using the Speedi-Sleeve repair kit, repair the running surface under the seal.
The seal shown in Fig. 14.2 is a relatively simple design; most automotive seals are more complex. Dust lips are often used to keep outside contaminants away from the oil lip seals; such seals thus have undercuts that make demolding more difficult. Fluoroelastomer compounds used for such undercut shapes must have reasonably high elongation at break at molding temperatures to avoid tearing the part during demolding. The metal insert is often U-shaped, and stock may be molded to form a thin layer over the outside of the insert. Since both compression and injection molding methods are used, suppliers of fluoroelastomers for shaft-seal applications often must provide different versions of the same polymer composition-medium to high viscosity for compression molding, and low to medium viscosity for injection molding. Different precompounds may be necessary to accommodate relatively long compression-molding times at low temperature and very short injection-molding times at high temperature.


With minor lip
Type code
Table 2 b): Common types of oil seals (without spring)


Before installing the oil seal, it is important to lubricate it to reduce friction and prevent damage during installation. A silicone-based lubricant is recommended for most applications. If the oil seal is to be installed in a high-temperature or high-pressure environment, a more specialized lubricant may be required.