DETROIT DIESEL 53
1.3.4
CRANKSHAFT MAIN BEARINGS
The crankshaft main bearing shells (Figs. 1 and 2) are
precision made and are replaceable without machin-
ing. They consist of an upper bearing shell seated in
each cylinder block main bearing support and a lower
bearing shell seated in each main bearing cap. The
bearing shells are prevented from endwise or radial
movement by a tang at the parting line at one end of
each bearing shell. The tangs on the lower bearing
shells are off-center and the tangs on the upper
bearing shells are centered to aid correct installation.
On In-line
engines, a 7/16" oil hole
in the groove of each upper bearing shell, midway
between the parting lines, registers with a vertical oil
passage in the cylinder block. Lubricating oil, under
pressure, passes from the cylinder block oil gallery by
way of the bearing shells to the drilled passages in the
crankshaft, then to the connecting rods and connecting
rod bearings.
Fig. 1 - Main Bearing Shells, Bearing Caps
and Crankshaft Thrust Washers -- In-Line
Engines
SEC. 1.3.4 Page 1
April. 1974
