DETROIT DIESEL 53
1.3.4 Main Bearings
The lower main bearing shells have no oil grooves;
therefore, the upper and lower bearing shells must not
be interchanged.
Thrust washers (Fig. 1)
on each side of the
rear main bearing, 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. All of the main bearing load is carried
on the lower bearings; therefore. wear will occur on
the lower bearing 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
Fig. 5 Removing Upper Rear Main Bearing
time, as outlined below and examine the bearing
Shell
shells.
Remove Main Bearing Shells (Crankshaft in
Place )
The bearing caps are numbered 1, 2, 3, etc.. indicating
their respective positions and, when removed, must
always be reinstalled in their original position.
All crankshaft main bearing journals, except the rear
journal, are drilled for an oil passage. Therefore, the
procedure for removing the upper bearing shells with
the crankshaft in place is somewhat different on the
drilled journals than on the rear journal.
Remove the main bearing shells as follows:
I. Drain ,and remove the oil pan to expose the main
bearing caps.
2. Remove the oil pump and the oil inlet pipe and
screen assembly.
Fig. 4 - Removing Upper Main Bearing Shell
(Except Rear Main)
Page 2
