1.6.2
DETROIT DIESEL 53
CONNECTING ROD BEARINGS
The connecting rod bearing shells (Fig. 1) are
Inspection
precision made and are replaceable without shim
adjustments. They consist of an upper bearing shell
Bearing failures may result from deterioration (acid
seated in the connecting rod and a lower bearing shell
formation) or contamination of the oil or loss of oil.
seated in the connecting rod cap. The bearing shells
An analysis of the lubricating oil may be required to
are prevented from endwise or radial movement by a
determine if corrosive acid and sulphur are present
tang at the parting line at one end of each bearing
which cause acid etching, flaking and pitting. Bearing
shell.
seizure may be due to low oil or no oil.
After removal, clean the bearings and inspect them for
scoring, pitting, flaking, etching or signs of overheat-
ing. If any of these defects are present, the bearings
The upper and lower connecting rod bearing shells are
must be discarded. The upper bearing shells, which
different and are not interchangeable. The upper
bearing shell has two short oil grooves and two oil
holes; each groove begins at the end of the bearing
shell and terminates at an oil hole. The lower bearing
shell has a continuous oil groove from one end of the
shell to the other. These grooves maintain a
continuous registry with the oil hole in the crankshaft
connecting rod journal, thereby providing a constant
supply of lubricating oil to the connecting rod
bearings, piston pin bushings and spray nozzle
through the oil passage in the connecting rod.
Remove bearing Shells
The connecting rod bearing caps are numbered 1, 2, 3,
etc. on an In-line engine
with matching numbers stamped on
the connecting rods. When removed, each bearing cap
and the bearing shells must always be reinstalled on
the original connecting rod.
Remove the connecting rod bearings as follows:
1. Drain the oil and remove the oil pan.
2. Remove the oil inlet pipe and screen assembly.
3. Remove one connecting rod bearing cap. Push the
connecting rod and piston assembly up into the
cylinder liner far enough to permit removal of the
upper bearing shell. Do not pound on the edge of the
bearing shell with a sharp tool.
4. Inspect the upper and lower bearing shells as
outlined under Inspection.
Fig. 1 - Connecting Rod and Bearing Shells
5. Install the bearing shells and bearing cap before
another connecting rod bearing cap is removed.
SEC. 1.6.2 Page 1
April, 1974
