1.3.4 Main Bearings
DETROIT DIESEL 53
Fig. 2. Shell Upper Main Bearing
Fig. 3. Removing Main Bearing Upper Shell (Except
centered to aid in the correct installation of the main
Rear Main) Crankshaft in Place
bearing shells.
Crankshaft thrust washers (Fig. 1.) absorb the
crankshaft thrust. The lower halves of the two-piece
washers are doweled to the bearing cap, the upper
halves are not doweled.
Main bearing trouble is ordinarily indicated by low or no
oil pressure and, in extreme cases, may cause the
flywheel to wobble. All of the main bearing load is
carried on the lower bearings; therefore, wear will occur
on the lower shells first. The condition of the lower main
bearing shells may be observed by removing the main
bearing caps.
If main bearing trouble is suspected, remove the oil pan,
then remove the main bearing caps, one at a time, as
outlined below and examine the bearing shells.
Remove Main Bearing Shells (Crankshaft in Place)
All crankshaft main bearing journals, except the rear,
are drilled for an oil passage. The procedure, therefore,
for removing the shells with the crankshaft in place is
somewhat different on the drilled journals than on the
one at the rear which is not drilled. Remove the main
bearing shells as follows:
1. Drain and remove the oil pan to expose the
main bearing caps.
Fig. 4. Removing Rear Main Bearing Upper Shell
Crankshaft in Place
1972 General Motors Corp.
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