DETROIT DIESEL 53
Fig. 4 - Typical Ridging of Crankshaft
After the crankshaft has been removed, clean and inspect it thoroughly before reinstalling it in the engine.
Remove the plugs and clean out the oil passages thoroughly with a stiff wire brush. Clean the crankshaft with fuel oil and
dry it with compressed 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
Used crankshafts will sometimes show a certain amount of ridging caused by the groove in the upper main bearing shell
or lower connecting rod bearing 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 engine operation.
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 .001 ", the crankshaft may have to be reground.
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 Section 1.3.2.
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.
Check the oil pump drive gear and the crankshaft timing gear for worn or chipped teeth. Replace the gears, if necessary.
Inspect the crankshaft for cracks as outlined under Inspection for Cracks.
Fig. 5 - Critical Crankshaft Loading Zones