Wrangler 2WD V6-3.8L (2008)
NOTE: The total clearance of the main bearings can only be determined with the engine in the vehicle by removing the weight of the crankshaft
. This can be accomplished by either of two following methods:
1. Preferred method:
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Shim the bearings adjacent to the bearing to be checked in order to remove the clearance between upper bearing shell and the crankshaft. This
can be accomplished by placing a minimum of 0.254 mm (0.010 in.) shim (e. g. cardboard, matchbook cover, etc.) between the bearing shell
and the bearing cap on the adjacent bearings and tightening bolts to 14-20 Nm (10-15 ft. lbs.).
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When checking #1 main bearing shim #2 main bearing.
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When checking #2 main bearing shim #1 & #3 main bearing.
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When checking #3 main bearing shim #2 & #4 main bearing.
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When checking #4 main bearing shim #3 main bearing.
NOTE: Remove all shims before reassembling engine.
2. Alternative Method:
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Support the weight of the crankshaft with a jack under the counterweight adjacent to the bearing being checked.
3. Remove oil film from surface to be checked. Plastigage is soluble in oil.
4. Place a piece of Plastigage (1) across the entire width of the bearing shell in the cap approximately 6.35 mm (1/4 in.) off center and away from the
oil holes. (In addition, suspected areas can be checked by placing the Plastigage in the suspected area). Torque the bearing cap bolts of the bearing
being checked to the proper specifications.
5. Remove the bearing cap and compare the width of the flattened Plastigage (1) with the scale provided on the package. Locate the band closest to
the same width. This band shows the amount of clearance in thousandths. Differences in readings between the ends indicate the amount of taper
present. Record all readings taken. See: Specifications/Engine Specifications Plastigage generally is accompanied by two scales. One scale is in
inches, the other is a metric scale.
NOTE: Plastigage is available in a variety of clearance ranges. Use the most appropriate range for the specifications you are checking.
PLASTIGAGE METHOD-ENGINE OUT-OF-VEHICLE
6. With engine in the inverted position (crankshaft up) and mounted on a repair stand, remove main journal cap.
7. Remove oil from journal and bearing shell.
8. Cut Plastigage (1) to same length as width of the bearing and place it in parallel with the journal axis (1).
9. Carefully install the main bearing cap and tighten the bolts to specified torque See: Specifications/Engine Specifications.
CAUTION: Do not rotate crankshaft or the Plastigage will be smeared.
10. Carefully remove the bearing cap and measure the width of the Plastigage (1) at the widest part using the scale on the Plastigage package. Refer to
Engine Specifications for proper clearances See: Specifications/Engine Specifications. If the clearance exceeds the specified limits, replace the
main bearing(s) with the appropriate size, and if necessary, have the crankshaft machined to next undersize.