TM 5-3810-300-24&P-3
1.3.2
CRANKSHAFT OIL SEALS
An oil seal is used at each end of the crankshaft to retain
Remove Crankshaft Oil Seals
the lubricating oil in the crankcase. The sealing lips of
the oil seals are held firmly, but not tight, against the
Remove the crankshaft front cover (Section 1.3.5) and
crankshaft sealing surfaces by a coil spring.
the flywheel housing (Section 1.5) and remove the oil
seals as follows:
The front oil seal is pressed into the crankshaft front
cover, and the lip of the seal bears against a removable
1. Support the forward face of the front cover or the
spacer or vibration damper inner cone on the end of the
rear face of flywheel housing on wood blocks.
crankshaft, next to the lubricating oil pump drive gear
2. Drive the oil seal out and clean the seal bore in
front cover or flywheel housing. Discard oil seal.
A single-lip oil seal is used at the rear end of the
crankshaft of some engines. A double-lip oil seal is used
When necessary, an oil seal may be removed without
in engines where there is oil on both sides of the seal;
removing the front cover or flywheel housing (except a
the lips of the seal face in opposite directions. The rear
front cover that is used with trunnion mounts this cover
oil seal is pressed into the flywheel housing (Figs. 3 and
must be removed). This may be done by drilling
4).
diametrically opposite holes in the seal casing and
threading metal screws, backed by flat washers, into the
Oil leaks indicate worn or damaged oil seals. Oil seals
casing. Remove the seal by prying against the washers
may become worn or damaged due to improper
with pry bars.
installation, excessive main bearing clearances,
excessive flywheel housing bore runout or grooved
Inspection
sealing surfaces on the crankshaft or oil seal spacers.
To prevent a repetition of any oil seal leaks, these
Inspect the rear end of the crankshaft for wear caused by
conditions must be checked and corrected.
the rubbing action of the oil seal, dirt build-up or fretting
by the action of the flywheel. The crankshaft surface
must be clean and smooth to prevent damaging the seal
lip when a new oil seal is installed. Slight ridges may be
removed from the crankshaft as outlined under
The maximum runout of the oil seal bore in the flywheel
Fig. 1. Crankshaft Front Oil Seal
Fig. 2. Crankshaft Front Oil Seal Mounting
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