CRANKSHAFT OIL SEALS
An oil seal is used at each end of the crankshaft to
retain the lubricating oil in the crankcase. The sealing
lips of the oil seals are held firmly, but not tight, against
the crankshaft sealing surfaces by a coil spring.
The front oil seal is pressed into the crankshaft front
cover, and the lip of the seal bears against a removable
spacer or vibration damper inner cone on the end of the
crankshaft, next to the lubricating oil pump drive gear
A single-lip oil seal is used at the rear end of the
crankshaft, (Fig. 3). The rear oil seal is pressed into the
Oil leaks indicate worn or damaged oil seals. Oil seals
may become worn or damaged due to improper
installation, excessive main bearing clearances,
excessive flywheel housing bore runout or grooved
sealing surfaces on the crankshaft or oil seal spacers.
Fig. 2. Crankshaft Front Oil Seal Mounting
To prevent a repetition of any oil seal leaks, these
conditions must be checked and corrected.
1. Support the forward face of the front cover or the
rear face of the flywheel housing on wood blocks.
Remove Crankshaft Oil Seals
2. Drive the oil seal out and clean the seal bore in the
front cover or flywheel housing. Discard the oil seal.
seals as follows:
Fig. 1. Crankshaft Front Oil Seal
Fig. 3. Crankshaft Rear Oil Seal-Single Lip