DETROIT DIESEL 53
Carefully inspect the front and rear end of the
crankshaft in the area of the oil seal contact surface
for evidence of a rough or grooved condition. Any
imperfections of the oil seal contact surface will result
in oil leakage at this point.
Slight ridges on the crankshaft oil seal contact surfaces
may be cleaned up with emery cloth and crocus cloth
in the same manner as detailed for the crankshaft
journals. If the crankshaft cannot be cleaned up
satisfactorily, the oil seals may be repositioned in the
flywheel housing and front cover as outlined in
Check the crankshaft thrust surfaces for excessive wear
or grooving. If only slightly worn, the surfaces may be
dressed with a stone. Otherwise it will be necessary to
regrind the thrust surfaces.
Fig. 4 - Typical Ridging of Crankshaft
Check the oil pump drive gear and the crankshaft
timing gear for worn or chipped teeth. Replace the
After the crankshaft has been removed, clean and
inspect it thoroughly before reinstalling it in the
Remove the plugs and clean out the oil passages
thoroughly with a stiff wire brush. Clean the
Inspect the crankshaft for cracks as outlined under
crankshaft with fuel oil and dry it with compressed
Inspection for Cracks.
air. Then reinstall the plugs.
Inspect the keyways for evidence of cracks or wear.
Replace the crankshaft, if necessary.
If the crankshaft shows evidence of excessive
overheating, replace the crankshaft since the heat
treatment has probably been destroyed.
Used crankshafts will sometimes show a certain
amount of ridging caused by the groove in the upper
main bearing shell or lower connecting rod hearing
shell (Fig. 4). Ridges exceeding .0002" must be
removed. If the ridges are not removed, localized high
unit pressures on new bearing shells will result during
The ridges may be removed by working crocus cloth,
wet with fuel oil, around the circumference of the
crankshaft journal. If the ridges are greater than
.0005 ", first use 120 grit emery cloth to clean up the
ridge, 240 grit emery cloth for finishing and wet crocus
cloth for polishing. Use of a piece of rawhide or other
suitable rope wrapped around the emery cloth or
crocus cloth and drawn back and forth will minimize
the possibility of an out-of-round condition developing
(keep the strands of rawhide apart to avoid bind). If
rawhide or rope is not used, the crankshaft should be
rotated at intervals. If the ridges are greater than
Fig. 5 - Critical Crankshaft Loading Zones
.001 ", the crankshaft may have to be reground.
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