Bearing Running Clearance - Navistar INTERNATIONAL DT 466 Service Manual

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Figure 318 Effects of bearing crush
1. Diameter at open ends after bearing crush load
2. Diameter at open ends before bearing crush load
NOTE: Connecting rod bearings must fit tightly in the
connecting rod bore. When bearings are inserted
in the connecting rod and cap, they protrude slightly
above the parting surface. This protrusion is required
to achieve bearing crush. Bearing crush forces the
ends inward at the parting line when a load is applied
by tightening the bolts. Some snap may be lost in
normal use, but bearing replacement is not required
because of a nominal loss of snap.
When the connecting rod bearing is installed and the
connecting rod cap bolts are tightened, the bearing is
compressed, ensuring a positive contact between the
backside of the bearing and the machined surface of
the connecting rod bore.

Bearing Running Clearance

1. Install new bearings in the connecting rod and
cap.
CAUTION: To prevent engine damage,
connecting rod cap and connecting rod with matching
serial numbers on the same side. If the rod cap is
reversed or not installed on its matching connecting
rod, the fractured mating surfaces will be damaged.
This can loosen the rod cap. A new connecting rod
assembly must be installed.
2. Match serial numbers on the connecting rod
and rod cap (on same side of fractured rod)
and install the connecting rod and cap on the
crankshaft. See Installing Piston and Connecting
Rod Assembly (page237 ).
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
POWER CYLINDERS
3. Remove the connecting rod cap. Wipe the oil
from the face of the bearings in the cap and the
exposed portion of the crankshaft.
4. Place a piece of undamaged Plastigage® across
the full width of the connecting rod bearing, about
6 mm (0.25 in) from the center of the connecting
rod cap.
CAUTION: To prevent engine damage, do not
torque-to-yield connecting rod cap bolts while doing
this measurement procedure.
CAUTION: To prevent engine damage, when torquing
connecting rod bolts use a torque wrench that is
known to be accurate. Correct torque of connecting
rod cap bolts is important.
5. Install the connecting rod cap bolts and tighten to
109 N·m (80 lbf·ft).
NOTE: Do not turn the crankshaft. This will smear the
Plastigage® making it unusable.
Figure 319 Measuring Plastigage® with scale
6. Remove the connecting rod cap. The Plastigage®
install
material will adhere to the bearing shell or the
crankshaft. Do not remove the Plastigage®.
7. Use the Plastigage® paper scale to measure the
widest point of the flattened material. Numbers
in the graduated marks on the scale indicate the
running clearance in thousandths of an inch or
millimeters.
NOTE: If running clearance is not to specification, it
may be necessary to grind the crankshaft and install
an undersized bearings. Check running clearance
again before condemning the crankshaft.
EGES-265-2
Follow all warnings, cautions, and notes.
© 2009 Navistar, Inc.