POWER CYLINDERS 225
Connecting Rod Bearing Bore
1. Inspect the finished surface of the connecting
rod bearing bore for nicks, burrs, and scoring.
Replace connecting rod as required.
Figure 316 Connecting rod bearing bore for
out-of-round
2. Use an inside micrometer to measure the inside
diameter of the connecting rod bearing bore at
three locations that are 60 degrees apart. Record
the readings.
If the difference between measurement B and
the average of measurements A and C exceeds
the specification for out-of-round, replace the
connecting rod.
Figure 317 Measuring connecting rod bearing
bore taper
3. Use a telescoping gauge and an outside
micrometer to measure the inside diameter of
the connecting rod bearing bore at the edge of
each side of the bore. Record the readings.
If the difference between the two measurements
exceeds the bore taper specification, replace the
connecting rod assembly.
Bend and Twist
Engine component wear patterns can often be
identified and used to diagnose a problem. Some
common examples of connecting rod wear patterns
include the following:
• A shiny surface on the edge of the piston pin
bushing usually indicates that a connecting rod
is bent or a piston pin hole is not positioned
properly in relation to the piston skirt and piston
ring grooves.
• Abnormal wear on the connecting rod bearing
may indicate that a connecting rod is bent or the
bearing bore is too tapered.
• A twisted connecting rod will not create an
easily identifiable wear pattern, although
severely twisted connecting rods will disturb
the action of the entire piston and connecting rod
assembly and may be the cause of excessive oil
consumption.
If any of these conditions exist, use a suitable
alignment fixture to check the connecting rod for
bends and twists. Follow the instructions of the
alignment fixture manufacturer. If a bend or twist
exceeds the specification, replace the connecting
rod.
Bearing Fitting Procedures and Bearing Running
Clearance
CAUTION: To prevent engine damage, do not attempt
to reduce journal-to-bearing running clearance by
reworking the bearing cap or the bearings. Grind the
crankshaft to the next available under size or replace
crankshaft.
EGES-265-2
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© 2009 Navistar, Inc.
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