Jeep Grand Cherokee WK. Manual — part 1160
STANDARD PROCEDURE
CONNECTING ROD BEARING FITTING
Inspect the connecting rod bearings for scoring (10
and (3). Check the bearings for normal wear patterns,
scoring, grooving, fatigue and pitting. Replace any
bearing that shows abnormal wear.
Inspect the connecting rod journals for signs of scor-
ing, nicks and burrs.
Misaligned or bent connecting rods can cause abnor-
mal wear on pistons, piston rings, cylinder walls, con-
necting rod bearings and crankshaft connecting rod
journals. If wear patterns or damage to any of these
components indicate the probability of a misaligned
connecting rod, inspect it for correct rod alignment.
Replace misaligned, bent or twisted connecting rods.
1. Wipe the oil from the connecting rod journal.
2. Lubricate the upper bearing insert (2) and position
in connecting rod (1). Center bearing insert in con-
necting rod
3. Measure at point A and point B. Measurement
should be less then .50mm (.0196 in.).
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4. Use piston ring compressor (3) and Guide Pins
Special Tool 8507 (4) to install the rod and piston
assemblies. The oil slinger slots in the rods must
face front of the engine. The “F”’s (1) near the pis-
ton wrist pin bore should point to the front of the
engine.
5. Install the lower bearing insert in the bearing cap.
Center bearing insert in connecting rod. The lower
insert must be dry. Place strip of Plastigage (1)
across full width of the lower insert at the center of
bearing cap. Plastigage must not crumble in use. If
brittle, obtain fresh stock.
6. Install bearing cap and connecting rod on the jour-
nal and tighten bolts to 27 N·m (20 ft. lbs.) plus a
90° turn. DO NOT rotate crankshaft. Plastigage will
smear, resulting in inaccurate indication.
7. Remove the bearing cap and determine amount of
bearing-to-journal
clearance
by
measuring
the
width of compressed Plastigage (2). Refer to
Engine Specifications for the proper clearance.
Plastigage should indicate the same clearance
across the entire width of the insert. If the
clearance varies, it may be caused by either a
tapered journal, bent connecting rod or foreign
material trapped between the insert and cap or
rod.
8. If the correct clearance is indicated, replacement of
the bearing inserts is not necessary. Remove the
Plastigage from crankshaft journal and bearing insert. Proceed with installation.
9. If bearing-to-journal clearance exceeds the specification, determin which services bearing set to use the bearing
sizes are as follows:
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ENGINE - 3.7L SERVICE INFORMATION
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Bearing Mark
SIZE
USED WITH JOURNAL SIZE
.025 US
.025 mm
57.883-57.867 mm
(.001 in.)
(2.2788-2.2783 in.)
Std.
STANDARD
57.908-57.892 mm
(2.2798-2.2792 in.)
.250 US
.250 mm
57.658-57.646 mm
(.010 in.)
(2.2700-2.2695 in.)
CAUTION: Connecting Rod Bolts are Torque to Yield Bolts and Must Not Be Reused. Always replace the
Rod Bolts whenever they are loosened or removed.
10. Repeat the Plastigage measurement to verify your bearing selection prior to final assembly.
11. Once you have selected the proper insert, install the insert and cap. Tighten the connecting rod bolts to 27 N·m
(20 ft. lbs.) plus a 90° turn.
Slide snug-fitting feeler gauge between the connecting
rod and crankshaft journal flange. Refer to Engine
Specifications for the proper clearance. Replace the
connecting rod if the side clearance is not within
specification.
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PISTON FITTING
1. To correctly select the proper size piston, a cylinder
bore gauge (2), capable of reading in 0.003 mm (
.0001 in.) INCREMENTS is required. If a bore
gauge is not available, do not use an inside
micrometer.
2. Measure the inside diameter of the cylinder bore at
a point 38.0 mm (1.5 inches) below top of bore (4).
Start perpendicular (across or at 90 degrees) to the
axis of the crankshaft at point A and then take an
additional bore reading 90 degrees to that at point
B.
3. The coated pistons will be serviced with the piston
pin and connecting rod pre-assembled.
4. The coating material (1) and (2) is applied to the
piston after the final piston machining process.
Measuring the outside diameter of a coated piston
will not provide accurate results. Therefore measur-
ing the inside diameter of the cylinder bore with a
dial Bore Gauge is MANDATORY. To correctly
select the proper size piston, a cylinder bore gauge
capable of reading in 0.003 mm (.0001 in.) incre-
ments is required.
5. Piston installation into the cylinder bore requires
slightly more pressure than that required for non-
coated pistons. The bonded coating on the piston
will give the appearance of a line-to-line fit with the
cylinder bore.
REMOVAL
1. Disconnect negative cable from battery.
2. Remove the following components:
•
Oil pan and gasket/windage tray (Refer to 9 - ENGINE/LUBRICATION/OIL PAN - REMOVAL).
•
Cylinder head(s) (Refer to 9 - ENGINE/CYLINDER HEAD - REMOVAL) and (Refer to 9 - ENGINE/CYLINDER
HEAD - REMOVAL).
3. If necessary, remove top ridge of cylinder bores with a reliable ridge reamer before removing pistons from cyl-
inder block. Be sure to keep tops of pistons covered during this operation. Pistons and connecting rods
must be removed from top of cylinder block. When removing piston and connecting rod assemblies from the
engine, rotate crankshaft so the each connecting rod is centered in cylinder bore.
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