DETROIT DIESEL 53
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 lower front cover on In-line engine (Fig. 1).
A single-lip oil seal is used at the rear end of the crankshaft of most industrial engines. A double-lip oil seal is used in
engines where there is oil on both sides of the oil seal; the lips of the seal face in opposite directions. The rear oil seal is
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. To prevent a repetition of any oil seal leaks, these conditions must be checked and corrected.
Remove Crankshaft Oil Seals
remove the oil seals as follows:
1. Support the forward face of the front cover, or the outboard bearing support, on two wood blocks next to the oil seal
bore. Then press or drive the oil seal out of the front cover or the outboard bearing support. Discard the oil seal.
2. Support the forward face of the flywheel housing on In-line engines on two wood blocks next to the oil seal bore.
Then press or drive the oil seal out of the housing. Discard the oil seal.
3. Clean the oil seal bore in the front cover, outboard bearing support or flywheel housing thoroughly before installing a
new oil seal.
When necessary, an oil seal may be removed without removing the front cover, outboard bearing support or flywheel
housing. This may be done by drilling diametrically opposite holes in the seal casing and threading metal screws, backed
by flat washers, into the casing. Remove the seal by prying against the washers with pry bars.
Inspect the front and rear end of the crankshaft for wear due to the rubbing action of the oil seal, dirt build-up or fretting
caused by action of the flywheel.
Fig. 1 - Crankshaft Front Oil Seal
Fig. 2 - Crankshaft Rear Oil Seal (In-Line Engines)