Jeep XJ. Manual — part 304
(Fig. 37). Refer to Engine Specifications for the
proper clearance.
Plastigage should indicate the same clearance
across the entire width of the insert. If clearance var-
ies, it may indicate a tapered journal or foreign
material trapped behind the insert.
If the specified clearance is indicated and there are
no abnormal wear patterns, replacement of the bear-
ing inserts is not necessary. Remove the Plastigage
from the crankshaft journal and bearing insert. Pro-
ceed to Crankshaft Main Bearing—Installation.
If the clearance exceeds specification, install a pair
of 0.025 mm (0.001 inch) undersize bearing inserts
and measure the clearance as described in the previ-
ous steps.
The clearance indicate with the 0.025 mm (0.001
inch) undersize insert pair installed will determine if
this insert size or some other combination will pro-
vide the specified clearance. FOR EXAMPLE: If the
clearance was 0.0762 mm (0.003 inch) originally, a
pair of 0.0254 mm (0.001 inch) undersize inserts
would reduce the clearance by 0.0254 mm (0.001
inch). The clearance would then be 0.0508 mm (0.002
inch) and within the specification. A 0.051 mm (0.002
inch) undersize bearing insert and a 0.0254 mm
(0.001 inch) undersize insert would reduce the origi-
nal clearance an additional 0.0127 mm (0.0005 inch).
The clearance would then be 0.0381 mm (0.0015
inch).
CAUTION: Never use a pair of inserts that differ
more than one bearing size as a pair.
FOR EXAMPLE: DO NOT use a standard size
upper insert and a 0.051 mm (0.002 inch) undersize
lower insert.
Fig. 36 Crankshaft Journal Size Paint I. D. Location
1 – NO. 7 MAIN JOURNAL SIZE PAINT MARK
2 – NO. 6 CONNECTING ROD JOURNAL SIZE PAINT MARK
3 – NO. 1 CONNECTING ROD JOURNAL SIZE PAINT MARK
4 – NO. 1 MAIN JOURNAL SIZE PAINT MARK
BEARING INSERT PAIRS CHART
INSERT
CORRECT
INCORRECT
UPPER
STANDARD
STANDARD
LOWER
0.025 mm
(0.001 in.)
UNDERSIZE
0.051 mm
(0.002 in.)
UNDERSIZE
Fig. 37 Measuring Bearing Clearance with
Plastigage
1 – PLASTIGAGE SCALE
2 – COMPRESSED PLASTIGAGE
9 - 84
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XJ
SERVICE PROCEDURES (Continued)
If the clearance exceeds specification using a pair
of 0.051 mm (0.002 inch) undersize bearing inserts,
measure
crankshaft
journal
diameter
with
a
micrometer. If the journal diameter is correct, the
crankshaft bore in the cylinder block may be mis-
aligned, which requires cylinder block replacement or
machining to true bore.
Replace the crankshaft or grind to accept the
appropriate undersize bearing inserts if:
• Journal diameters 1 through 6 are less than
63.4517 mm (2.4981 inches)
• Journal 7 diameter is less than 63.4365 mm
(2.4975 inches).
Once the proper clearances have been obtained,
proceed to Crankshaft Main Bearing—Installation.
MAIN BEARING JOURNAL DIAMETER
(CRANKSHAFT REMOVED)
Remove the crankshaft from the cylinder block
(refer to Cylinder Block - Disassemble).
Clean the oil off the main bearing journal.
Determine the maximum diameter of the journal
with a micrometer. Measure at two locations 90°
apart at each end of the journal.
The maximum allowable taper and out of round is
0.013 mm (0.0005 inch). Compare the measured
diameter with the journal diameter specification
(Main Bearing Fitting Chart). Select inserts required
to obtain the specified bearing-to-journal clearance.
Install the crankshaft into the cylinder block (refer
to Cylinder Block - Assemble and Crankshaft Main
Bearings - Installation).
MAIN BEARING FITTING CHART
Crankshaft Journals #1-6
Corresponding Crankshaft Bearing Insert
Color Code
Diameter
Upper Insert Size
Lower Insert Size
Yellow
63.5025 -63.4898 mm
Yellow - Standard
Yellow - Standard
(2.5001 - 2.4996 in.)
Orange
63.4898 - 63.4771 mm
Yellow - Standard
Blue - Undersize
0.025 mm (0.001 in.)
(2.4996 - 2.4991 in.)
0.0127 mm (0.0005 in.)
Undersize
Blue
63.4771 - 63.4644 mm
Blue - Undersize
0.025 mm (0.001 in.)
Blue - Undersize
0.025 mm (0.001 in.)
(2.4991 - 2.4986 in.)
0.0254 mm (0.001 in.)
Undersize
Green
63.4644 - 63.4517 mm
Blue - Undersize
0.025 mm (0.001 in.)
Green - Undersize
0.051 mm (0.002 in.)
(2.4986 - 2.4981 in.)
0.0381 mm (0.0015 in.)
Undersize
Red
63.2485 - 63.2358 mm
Red - Undersize
0.254 mm (0.010 in.)
Red - Undersize
0.254 mm (0.010 in.)
(2.4901 - 2.4896 in.)
0.254 mm (0.010 in.)
Undersize
XJ
4.0L ENGINE
9 - 85
SERVICE PROCEDURES (Continued)
Crankshaft Journal #7 Only
Corresponding Bearing Insert
Color Code
Diameter
Upper Insert Size
Lower Insert Size
Yellow
63.4873 - 63.4746 mm
Yellow - Standard
Yellow - Standard
(2.4995 - 2.4990 in.)
Orange
63.4746 - 63.4619 mm
Yellow - Standard
Blue - Undersize
0.025 mm (0.001 in.)
(2.4996 - 2.4991 in.)
0.0127 mm (0.0005 in.)
Undersize
Blue
63.4619 - 63.4492 mm
Blue - Undersize
0.025 mm (0.001 in.)
Blue - Undersize
0.025 mm (0.001 in.)
(2.4985 - 2.4980 in.)
0.0254 mm (0.001 in.)
Undersize
Green
63.4492 - 63.4365 mm
Blue - Undersize
0.025 mm (0.001 in.)
Green - Undersize
0.051 mm (0.002 in.)
(2.4980 - 2.4975 in.)
0.0381 mm (0.0015 in.)
Undersize
Red
63.2333 - 63.2206 mm
Red - Undersize
0.254 mm (0.010 in.)
Red - Undersize
0.254 mm (0.010 in.)
(2.4895 - 2.4890 in.)
0.254 mm (0.010 in.)
Undersize
FORM-IN-PLACE GASKETS
There are several places where form-in-place gas-
kets are used on the engine. DO NOT use form-in-
place gasket material unless specified. Care
must be taken when applying form-in-place gaskets.
Bead size, continuity and location are of great impor-
tance. Too thin a bead can result in leakage while too
much can result in spill-over. A continuous bead of
the proper width is essential to obtain a leak-free
joint.
Two types of form-in-place gasket materials are
used in the engine area (Mopar Silicone Rubber
Adhesive Sealant and Mopar Gasket Maker). Each
have different properties and cannot be used inter-
changeably.
MOPAR SILICONE RUBBER ADHESIVE SEALANT
Mopar Silicone Rubber Adhesive Sealant, normally
black in color, is available in 3 ounce tubes. Moisture
in the air causes the sealant material to cure. This
material is normally used on flexible metal flanges.
It has a shelf life of a year and will not properly cure
if over aged. Always inspect the package for the expi-
ration date before use.
MOPAR GASKET MAKER
Mopar Gasket Maker, normally red in color, is
available in 6 cc tubes. This anaerobic type gasket
material cures in the absence of air when squeezed
between smooth machined metallic surfaces. It will
not cure if left in the uncovered tube. DO NOT use
on flexible metal flanges.
SURFACE PREPARATION
Parts assembled with form-in-place gaskets may be
disassembled
without
unusual
effort.
In
some
instances, it may be necessary to lightly tap the part
with a mallet or other suitable tool to break the seal
between the mating surfaces. A flat gasket scraper
may also be lightly tapped into the joint but care
must be taken not to damage the mating surfaces.
Scrape or wire brush all gasket surfaces to remove
all loose material. Inspect stamped parts to ensure
gasket rails are flat. Flatten rails with a hammer on
a flat plate, if required. Gasket surfaces must be free
of oil and dirt. Make sure the old gasket material is
removed from blind attaching holes.
GASKET APPLICATION
Assembling parts using a form-in-place gasket
requires care.
Mopar Silicone Rubber Adhesive Sealant should be
applied in a continuous bead approximately 3 mm
(0.12 inch) in diameter. All mounting holes must be
circled. For corner sealing, a 3 or 6 mm (1/8 or 1/4
inch) drop is placed in the center of the gasket con-
9 - 86
4.0L ENGINE
XJ
SERVICE PROCEDURES (Continued)
tact area. Uncured sealant may be removed with a
shop towel. Components should be torqued in place
while the sealant is still wet to the touch (within 10
minutes). The use of a locating dowel is recom-
mended during assembly to prevent smearing the
material off location.
Mopar Gasket Maker should be applied sparingly
to one gasket surface. The sealant diameter should
be 1.00 mm (0.04 inch) or less. Be certain the mate-
rial surrounds each mounting hole. Excess material
can easily be wiped off. Components should be
torqued in place within 15 minutes. The use of a
locating dowel is recommended during assembly to
prevent smearing the material off location.
ENGINE PERFORMANCE
It is important that the vehicle is operating to its
optimum performance level to maintain fuel economy
and the lowest emission levels. If vehicle is not oper-
ating to these standards, refer to Engine Diagnosis
outlined in this section. The following procedures can
assist in achieving the proper engine diagnosis.
(1) Test cranking amperage draw. Refer to Electri-
cal Group 8B, Cold Cranking Test.
(2) Check intake manifold bolt torque; Refer to
Group 11, Exhaust System and Intake Manifold.
(3) Perform cylinder compression test. Refer to
Cylinder Compression Pressure Test in the Engine
Diagnosis area of this section.
(4) Clean or replace spark plugs as necessary and
adjust gap as specified in Electrical Group 8D.
Tighten to specifications.
(5) Test resistance of spark plug cables. Refer to
Electrical Group 8D, Spark Plug Cables.
(6) Inspect the primary wires. Test coil output volt-
age and primary resistance. Replace parts as neces-
sary. Refer to Electrical Group 8D, for specifications.
(7) Test fuel pump for pressure. Refer to Group 14,
Fuel System Specifications.
(8) The air filter elements should be replaced as
specified in Lubrication and Maintenance, Group 0.
(9) Inspect crankcase ventilation system as out
lined in Group 0, Lubrication and Maintenance. For
emission controls see Group 25, Emission Controls
for service procedures.
(10) Road test vehicle as a final test.
HONING CYLINDER BORES
Before honing, stuff plenty of clean shop towels
under the bores and over the crankshaft to keep
abrasive materials from entering the crankshaft
area.
(1) Used carefully, the Cylinder Bore Sizing Hone
C-823 equipped with 220 grit stones, is the best tool
for this job. In addition to deglazing, it will reduce
taper and out-of-round as well as removing light
scuffing, scoring or scratches. Usually a few strokes
will clean up a bore and maintain the required lim-
its.
CAUTION: DO NOT use rigid type hones to remove
cylinder wall glaze.
(2) Deglazing of the cylinder walls may be done if
the cylinder bore is straight and round. Use a cylin-
der surfacing hone, Honing Tool C-3501, equipped
with 280 grit stones (C-3501-3810). 20-60 strokes,
depending on the bore condition, will be sufficient to
provide a satisfactory surface. Using honing oil
C-3501-3880 or a light honing oil available from
major oil distributors.
CAUTION: DO NOT use engine or transmission oil,
mineral spirits or kerosene.
(3) Honing should be done by moving the hone up
and down fast enough to get a crosshatch pattern.
The hone marks should INTERSECT at 50° to 60°
for proper seating of rings (Fig. 38).
(4) A controlled hone motor speed between 200 and
300 RPM is necessary to obtain the proper cross-
hatch angle. The number of up and down strokes per
minute can be regulated to get the desired 50° to 60°
angle. Faster up and down strokes increase the cross-
hatch angle.
(5) After honing, it is necessary that the block be
cleaned to remove all traces of abrasive. Use a brush
to wash parts with a solution of hot water and deter-
gent. Dry parts thoroughly. Use a clean, white, lint-
free cloth to check that the bore is clean. Oil the
bores after cleaning to prevent rusting.
Fig. 38 Cylinder Bore Crosshatch Pattern
1 – CROSSHATCH PATTERN
2 – INTERSECT ANGLE
XJ
4.0L ENGINE
9 - 87
SERVICE PROCEDURES (Continued)
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