Measuring Bearing Clearance With Micrometer; Scoring Caused By Embedded Material; Locking Tab Inspection; Rod Beerlng Clearance Measurement With Plastigage - Jeep J-10 Series 1982 Technical & Service Manual

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GROOVES
60760
Fig. 1B-79 Scoring Caused by Imbedded Material
ABNORMAL CONTACT AREA
CAUSED BY LOCKING TABS NOT
FULLY SEATED OR BEING BENT
60758
Fig. 1B-80 Locking Tab Inspection
(5) Remove bearing cap and determine amount of
clearance by measuring width of compressed Plastigage
with scale on Plastigage envelope (fig. 1B-81). Correct
clearance is 0.001 to 0.0025 inch (0.025 to 0.064 mm).
COMPRESSED
PLASTIGAGE
.
41907
Fig. 1B-81 Rod Beerlng Clearance Measurement with Plastigage
ENGINES 1B-53
NOTE: Plastigage should maintain the same size
across the entire width of the insert. If size varies, it
may indicate a tapered journal, bent connecting rod or
foreign material trapped between the insert and rod.
(6) If correct clearance is indicated, bearing fitting
is not necessary. Remove Plastigage from crankshaft
and bearing and proceed to Installation.
CAUTION: Never use inserts that differ more than
one bearing size as a pair. For example, do not use a
standard upper and 0.002-inch undersize lower insert.
(7) If clearance exceeds specification, install 0.001-
inch (0.025 mm) undersize bearing inserts and measure
clearance as described in steps (1) through (5) above.
NOTE: The clearance indicated with a 0.001-inch (0.025
mm) undersize bearing installed will determine ifa pair
of 0.001-inch undersize inserts or some other com
bination is needed to provide the correct clearance. For
example, if the initial clearance was 0.003 inch (0.076
mm), 0.001-inch (0.025 mm) undersize inserts would re
duce clearance by 0.001 inch (0.025 mm). Oil clearance
would be 0.002 inch (0.051 mm) and within specification.
A 0.002-inch (0.051 mm) undersize insert and a 0.001-
inch (0.025 mm) undersize insert would reduce this
clearance an additional 0.0005 inch (0.013 mm). Oil
clearance would then be 0.0015 inch (0.038 mm).
(8) If oil clearance exceeds specification when pair
of 0.002-inch (0.051 mm) undersize inserts are installed,
measure connecting rod journal on crankshaft with mi
crometer. If journal size is correct (not less than 2.0934
inch or 53.172 mm), inside diameter of connecting rod is
incorrect and rod must be replaced. If journal size is
incorrect, replace crankshaft or grind journal to accept
suitable undersize bearing.
Measuring Bearing Clearance with Micrometer
(1) Wipe connecting rod journal on crankshaft
clean.
(2) Use micrometer to measure maximum diameter
of rod journal at four locations. Measure diameter at
two locations 90° apart at each end of journal.
(3) Examine for taper and out-of-round condition.
Correct tolerance is 0.0005-inch (0.013 mm) maximum
for both taper and out-of-round. If any rod journal is not
within specification, crankshaft must be replaced.
(4) Compare measurement obtained with journal
diameters listed in Connecting Rod Bearing Fitting
Chart and select inserts required to obtain specified
bearing clearance.
Installation
(1) Lubricate bearing surface of each insert with
clean engine oil.