bore JEEP GRAND CHEROKEE 2003 WJ / 2.G Owner's Manual

OPERATION
The master cylinder bore contains a primary and
secondary piston. The primary piston supplies
hydraulic pressure to the front brakes. The secondary
piston supplies hydraulic pressure to the rear brakes.
The master cylinder reservoir stores reserve brake
fluid for the hydraulic brake circuits.
DIAGNOSIS AND TESTING - MASTER
CYLINDER/POWER BOOSTER
NOTE: Inspect and repair any external fluid leaks
before performing test.
(1) Start engine and check booster vacuum hose
connections. A hissing noise indicates vacuum leak.
Correct any vacuum leak before proceeding.
(2)
Stop engine and shift transmission into Neutral.
(3) Pump brake pedal until all vacuum reserve in
booster is depleted.
(4) Press and hold brake pedal under light foot
pressure. The pedal should hold firm, if the pedal
falls away the master cylinder or HCU may be faulty
(internal leakage).
(5) Start engine and note pedal action. It should
fall away slightly under light foot pressure then hold
firm. If no pedal action is discernible, power booster,
vacuum supply, or vacuum check valve is faulty. Pro-
ceed to the POWER BOOSTER VACUUM TEST.
(6) If the POWER BOOSTER VACUUM TEST
passes, rebuild booster vacuum reserve as follows:
Release brake pedal. Increase engine speed to 1500
rpm, close the throttle and turn off the engine.
(7) Wait a minimum of 90 seconds and try brake
action again. Booster should provide two or more vac-
uum assisted pedal applications. If vacuum assist is
not provided, some component of the booster is faulty.
POWER BOOSTER VACUUM TEST
(1) Connect vacuum gauge to booster check valve
with short length of hose and T-fitting (Fig. 48).
(2) Start and run engine at curb idle speed for one
minute.
(3) Observe the vacuum supply. If vacuum supply
is not adequate, repair vacuum supply.
(4) Clamp hose shut between vacuum source and
check valve.
(5) Stop engine and observe vacuum gauge.
(6) If vacuum drops more than one inch HG (33
millibars) within 15 seconds, booster diaphragm,
check valve or check valve seal/grommet is faulty.
POWER BOOSTER CHECK VALVE TEST
(1) Disconnect vacuum hose from check valve.
(2)
Remove check valve and valve seal from booster.
(3) Use a hand operated vacuum pump for test.(4) Apply 51-67 kPa (15-20 in.) vacuum at large
end of check valve (Fig. 49).
(5) Vacuum should hold steady. If gauge on pump
indicates vacuum loss the check valve and seal
should be replaced.
Fig. 48 Typical Booster Vacuum Test Connections
1 - TEE FITTING
2 - SHORT CONNECTING HOSE
3 - CHECK VALVE
4 - CHECK VALVE HOSE
5 - CLAMP TOOL
6 - INTAKE MANIFOLD
7 - VACUUM GAUGE
Fig. 49 Vacuum Check Valve And Seal
1 - BOOSTER CHECK VALVE
2 - APPLY TEST VACUUM HERE
3 - VALVE SEAL
5 - 24 BRAKES - BASEWJ
MASTER CYLINDER (Continued)

CAUTION: When installing the serpentine accessory
drive belt, belt must be routed correctly. If not,
engine may overheat due to water pump rotating in
wrong direction.
(6) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(7) Connect negative battery cable.
(8) Start and warm the engine. Check for leaks.
WATER PUMP - 4.0L
DESCRIPTION
CAUTION: All 4.0L 6-cylinder engines are equipped
with a reverse (counterclockwise) rotating water
pump and thermal viscous fan drive assembly.
REVERSE is stamped or imprinted on the cover of
the viscous fan drive and inner side of the fan. The
letter R is stamped into the back of the water pump
impeller. Engines from previous model years,
depending upon application, may have been
equipped with a forward (clockwise) rotating water
pump. Installation of the wrong water pump or vis-
cous fan drive will cause engine over heating.
A centrifugal water pump circulates coolant
through the water jackets, passages, intake manifold,
radiator core, cooling system hoses and heater core.
The pump is driven from the engine crankshaft by a
single serpentine drive belt.
The water pump impeller is pressed onto the rear
of a shaft that rotates in bearings pressed into the
housing. The housing has two small holes to allow
seepage to escape. The water pump seals are lubri-
cated by the antifreeze in the coolant mixture. No
additional lubrication is necessary (Fig. 45).
DIAGNOSIS AND TESTINGÐWATER PUMP
LOOSE IMPELLER - 4.0L and 4.7L
NOTE: Due to the design of the 4.0L and 4.7L
engine water pumps, testing the pump for a loose
impeller must be done by verifying coolant flow in
the radiator. To accomplish this refer to the follow-
ing procedure.
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
(1) Drain coolant until the first row of cores is vis-
ible in the radiator (Refer to 7 - COOLING - STAN-
DARD PROCEDURE) 4.7L Engine or (Refer to 7 -
COOLING - STANDARD PROCEDURE) 4.0L
Engine.(2) Leaving the radiator cap off, start the engine.
Run engine until thermostat opens.
(3) While looking into the radiator through the
radiator fill neck, raise engine rpm to 2000 RPM.
Observe the flow of coolant from the first row of
cores.
(4) If there is no flow or very little flow visable,
replace the water pump.
INSPECTING FOR INLET RESTRICTIONS
Inadequate heater performance may be caused by
a metal casting restriction in the heater hose inlet.
DO NOT WASTE reusable coolant. If solution is
clean, drain the coolant into a clean container for
reuse.
WARNING: DO NOT LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM THE COOL-
ANT CAN OCCUR.
(1) Drain sufficient coolant from the radiator to
decrease the level below the heater hose inlet. On
4.7L engines this requires complete draining.
(2) Remove the heater hose.
(3) Inspect the inlet for metal casting flash or
other restrictions.
Fig. 45 Water Pump
1 - HEATER HOSE FITTING BORE
2 - WATER PUMP
3 - WATER PUMP HUB
7 - 50 ENGINEWJ
WATER PUMP - 4.7L (Continued)

ENGINE
TABLE OF CONTENTS
page page
ENGINE - 4.0L............................ 1ENGINE - 4.7L........................... 61
ENGINE - 4.0L
TABLE OF CONTENTS
page page
ENGINE - 4.0L
DESCRIPTION..........................2
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION............3
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - PERFORMANCE............4
DIAGNOSIS AND TESTINGÐ ENGINE
DIAGNOSIS - MECHANICAL..............6
DIAGNOSIS AND TESTINGÐCYLINDER
COMPRESSION PRESSURE..............8
DIAGNOSIS AND TESTING - CYLINDER
COMBUSTION PRESSURE LEAKAGE.......8
DIAGNOSIS AND TESTINGÐREAR SEAL
AREA LEAKS..........................9
STANDARD PROCEDURE
STANDARD PROCEDURE - FORM-IN-
PLACE GASKETS AND SEALERS..........9
STANDARD PROCEDURE - REPAIR
DAMAGED OR WORN THREADS.........10
STANDARD PROCEDUREÐHYDROSTATIC
LOCK...............................10
STANDARD PROCEDURE - CYLINDER
BORE HONING.......................10
STANDARD PROCEDURE - ENGINE CORE
AND OIL GALLERY PLUGS..............11
REMOVAL.............................11
INSTALLATION.........................13
SPECIFICATIONS
ENGINE - 4.0L........................14
TORQUE - 4.0L ENGINE................17
AIR CLEANER ELEMENT
REMOVAL - 4.0L........................18
INSTALLATION - 4.0L....................19
AIR CLEANER HOUSING
REMOVAL - 4.0L........................19
INSTALLATION - 4.0L....................19CYLINDER HEAD
DESCRIPTION.........................19
REMOVAL.............................19
CLEANING............................21
INSPECTION..........................21
INSTALLATION.........................21
CYLINDER HEAD COVER(S)
DESCRIPTION.........................22
REMOVAL.............................22
CLEANING............................23
INSPECTION..........................23
INSTALLATION.........................23
INTAKE/EXHAUST VALVES & SEATS
DESCRIPTION.........................23
STANDARD PROCEDURE - VALVE SERVICE . . 23
REMOVAL.............................25
INSTALLATION.........................25
ROCKER ARM / ADJUSTER ASSEMBLY
DESCRIPTION.........................26
OPERATION...........................26
REMOVAL.............................26
CLEANING............................26
INSPECTION..........................27
INSTALLATION.........................27
VALVE STEM SEALS
DESCRIPTION.........................27
VALVE SPRINGS
DESCRIPTION.........................28
STANDARD PROCEDURE - VALVE SPRING
TENSION TEST.......................28
REMOVAL.............................28
INSTALLATION.........................29
ENGINE BLOCK
CLEANING............................30
INSPECTION..........................30
CAMSHAFT & BEARINGS
DESCRIPTION.........................30
WJENGINE 9 - 1

CONDITION POSSIBLE CAUSES CORRECTION
3. Thin or diluted oil 3. Change oil to correct viscosity.
4. Excessive main bearing clearance 4. Measure bearings for correct
clearance. Repair as necessary
5. Excessive end play 5. Check crankshaft thrust bearing for
excessive wear on flanges
6. Crankshaft main journal out of
round or worn6. Grind journals or replace
crankshaft
7. Loose flywheel or torque converter 7. Inspect crankshaft, flexplate/
flywheel and bolts for damage.
Tighten to correct torque
LOW OIL PRESSURE 1. Low oil level 1. Check oil level and fill if necessary
2. Faulty oil pressure sending unit 2. Install new sending unit
3. Clogged oil filter 3. Install new oil filter
4. Worn oil pump 4. Replace oil pump assembly.
5. Thin or diluted oil 5. Change oil to correct viscosity.
6. Excessive bearing clearance 6. Measure bearings for correct
clearance
7. Oil pump relief valve stuck 7. Remove valve to inspect, clean
and reinstall
8. Oil pump suction tube loose,
broken, bent or clogged8. Inspect suction tube and clean or
replace if necessary
9. Oil pump cover warped or cracked 9. Install new oil pump
OIL LEAKS 1. Misaligned or deteriorated gaskets 1. Replace gasket
2. Loose fastener, broken or porous
metal part2. Tighten, repair or replace the part
3. Front or rear crankshaft oil seal
leaking3. Replace seal
4. Leaking oil gallery plug or cup
plug4. Remove and reseal threaded plug.
Replace cup style plug
EXCESSIVE OIL
CONSUMPTION OR SPARK
PLUGS OIL FOULED1. CCV System malfunction 1. (Refer to 25 - EMISSIONS
CONTROL/EVAPORATIVE
EMISSIONS - DESCRIPTION) for
correct operation
2. Defective valve stem seal(s) 2. Repair or replace seal(s)
3. Worn or broken piston rings 3. Hone cylinder bores. Install new
rings
4. Scuffed pistons/cylinder walls 4. Hone cylinder bores and replace
pistons as required
5. Carbon in oil control ring groove 5. Remove rings and de-carbon
piston
6. Worn valve guides 6. Inspect/replace valve guides as
necessary
7. Piston rings fitted too tightly in
grooves7. Remove rings and check ring end
gap and side clearance. Replace if
necessary
WJENGINE - 4.0L 9 - 7
ENGINE - 4.0L (Continued)

DIAGNOSIS AND TESTINGÐREAR SEAL AREA
LEAKS
Since it is sometimes difficult to determine the
source of an oil leak in the rear seal area of the
engine, a more involved inspection is necessary. The
following steps should be followed to help pinpoint
the source of the leak.
If the leakage occurs at the crankshaft rear oil seal
area:
(1) Disconnect the battery.
(2) Raise the vehicle.
(3) Remove torque converter or clutch housing
cover and inspect rear of block for evidence of oil.
Use a black light to check for the oil leak:
(a) Circular spray pattern generally indicates
seal leakage or crankshaft damage.
(b) Where leakage tends to run straight down,
possible causes are a porous block, distributor seal,
camshaft bore cup plugs, oil galley pipe plugs, oil
filter runoff, and main bearing cap to cylinder
block mating surfaces.
(4) If no leaks are detected, pressurized the crank-
case as outlined in (Refer to 9 - ENGINE/LUBRICA-
TION - DIAGNOSIS AND TESTING)
CAUTION: Do not exceed 20.6 kPa (3 psi).
(5) If the leak is not detected, very slowly turn the
crankshaft and watch for leakage. If a leak is
detected between the crankshaft and seal while
slowly turning the crankshaft, it is possible the
crankshaft seal surface is damaged. The seal area on
the crankshaft could have minor nicks or scratches
that can be polished out with emery cloth.
CAUTION: Use extreme caution when crankshaft
polishing is necessary to remove minor nicks or
scratches. The crankshaft seal flange is specially
machined to complement the function of the rear oil
seal.
(6) For bubbles that remain steady with shaft
rotation, no further inspection can be done until dis-
assembled. Refer to the service DiagnosisÐMechani-
cal, under the Oil Leak row, for components
inspections on possible causes and corrections.
(7) After the oil leak root cause and appropriate
corrective action have been identified, (Refer to 9 -
ENGINE/ENGINE BLOCK/CRANKSHAFT OIL
SEAL - REAR - REMOVAL), for proper replacement
procedures.
STANDARD PROCEDURE
STANDARD PROCEDURE - FORM-IN-PLACE
GASKETS AND SEALERS
There are numerous places where form-in-place
gaskets are used on the engine. Care must be taken
when applying form-in-place gaskets to assure
obtaining the desired results.Do not use form-in-
place gasket material unless specified.Bead size,
continuity, and location are of great importance. Too
thin a bead can result in leakage while too much can
result in spill-over which can break off and obstruct
fluid feed lines. A continuous bead of the proper
width is essential to obtain a leak-free gasket.
There are numerous types of form-in-place gasket
materials that are used in the engine area. Mopart
Engine RTV GEN II, MopartATF-RTV, and Mopart
Gasket Maker gasket materials, each have different
properties and can not be used in place of the other.
MOPARtENGINE RTV GEN II
MopartEngine RTV GEN II is used to seal com-
ponents exposed to engine oil. This material is a spe-
cially designed black silicone rubber RTV that
retains adhesion and sealing properties when
exposed to engine oil. Moisture in the air causes the
material to cure. This material is available in three
ounce tubes and has a shelf life of one year. After one
year this material will not properly cure. Always
inspect the package for the expiration date before
use.
MOPARtATF RTV
MopartATF RTV is a specifically designed black
silicone rubber RTV that retains adhesion and seal-
ing properties to seal components exposed to auto-
matic transmission fluid, engine coolants, and
moisture. This material is available in three ounce
tubes and has a shelf life of one year. After one year
this material will not properly cure. Always inspect
the package for the expiration date before use.
MOPARtGASKET MAKER
MopartGasket Maker is an anaerobic type gasket
material. The material cures in the absence of air
when squeezed between two metallic surfaces. It will
not cure if left in the uncovered tube. The anaerobic
material is for use between two machined surfaces.
Do not use on flexible metal flanges.
MOPARtGASKET SEALANT
MopartGasket Sealant is a slow drying, perma-
nently soft sealer. This material is recommended for
sealing threaded fittings and gaskets against leakage
of oil and coolant. Can be used on threaded and
machined parts under all temperatures. This mate-
rial is used on engines with multi-layer steel (MLS)
cylinder head gaskets. This material also will pre-
vent corrosion. MopartGasket Sealant is available in
a 13 oz. aerosol can or 4oz./16 oz. can w/applicator.
WJENGINE - 4.0L 9 - 9
ENGINE - 4.0L (Continued)

FORM-IN-PLACE GASKET AND SEALER
APPLICATION
Assembling parts using a form-in-place gasket
requires care but it's easier then using precut gaskets.
MopartGasket Maker material should be applied
sparingly 1 mm (0.040 in.) diameter or less of sealant
to one gasket surface. Be certain the material sur-
rounds each mounting hole. Excess material can eas-
ily be wiped off. Components should be torqued in
place within 15 minutes. The use of a locating dowel
is recommended during assembly to prevent smear-
ing material off the location.
MopartEngine RTV GEN II or ATF RTV gasket
material should be applied in a continuous bead
approximately 3 mm (0.120 in.) in diameter. All
mounting holes must be circled. For corner sealing, a
3.17 or 6.35 mm (1/8 or 1/4 in.) drop is placed in the
center of the gasket contact 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 usage of a
locating dowel is recommended during assembly to
prevent smearing material off the location.
MopartGasket Sealant in an aerosol can should be
applied using a thin, even coat sprayed completely
over both surfaces to be joined, and both sides of a
gasket. Then proceed with assembly. Material in a
can w/applicator can be brushed on evenly over the
sealing surfaces. Material in an aerosol can should be
used on engines with multi-layer steel gaskets.
STANDARD PROCEDURE - REPAIR DAMAGED
OR WORN THREADS
CAUTION: Be sure that the tapped holes maintain
the original center line.
Damaged or worn threads can be repaired. Essen-
tially, this repair consists of:
²Drilling out worn or damaged threads.
²Tapping the hole with a special Heli-Coil Tap, or
equivalent.
²Installing an insert into the tapped hole to bring
the hole back to its original thread size.
STANDARD PROCEDUREÐHYDROSTATIC LOCK
CAUTION: DO NOT use the starter motor to rotate
the crankshaft. Severe damage could occur.
When an engine is suspected of hydrostatic lock
(regardless of what caused the problem), follow the
steps below.
(1) Perform the Fuel Pressure Release Procedure
(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY -
STANDARD PROCEDURE).(2) Disconnect the negative cable(s) from the bat-
tery.
(3) Inspect air cleaner, induction system, and
intake manifold to ensure system is dry and clear of
foreign material.
(4) Place a shop towel around the spark plugs to
catch any fluid that may possibly be under pressure
in the cylinder head. Remove the spark plugs.
(5) With all spark plugs removed, rotate the crank-
shaft using a breaker bar and socket.
(6) Identify the fluid in the cylinders (coolant, fuel,
oil, etc.).
(7) Be sure all fluid has been removed from the
cylinders.
(8) Repair engine or components as necessary to
prevent this problem from occurring again.
(9) Squirt a small amount of engine oil into the
cylinders to lubricate the walls. This will prevent
damage on restart.
(10) Install new spark plugs. Tighten the spark
plugs to 41 N´m (30 ft. lbs.) torque.
(11) Drain engine oil. Remove and discard the oil
filter.
(12) Install the drain plug. Tighten the plug to 34
N´m (25 ft. lbs.) torque.
(13) Install a new oil filter.
(14) Fill engine crankcase with the specified
amount and grade of oil. (Refer to LUBRICATION &
MAINTENANCE - SPECIFICATIONS).
(15) Connect the negative cable(s) to the battery.
(16) Start the engine and check for any leaks.
STANDARD PROCEDURE - CYLINDER BORE
HONING
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 scuff-
ing, scoring and scratches. Usually, a few strokes will
clean up a bore and maintain the required limits.
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). about 20-60
strokes, depending on the bore condition, will be suf-
ficient to provide a satisfactory surface. Using honing
oil C-3501-3880, or a light honing oil, available from
major oil distributors.
9 - 10 ENGINE - 4.0LWJ
ENGINE - 4.0L (Continued)

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 40É to 60É
for proper seating of rings (Fig. 3).
(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 40É to 60É
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.
STANDARD PROCEDURE - ENGINE CORE AND
OIL GALLERY PLUGS
Using a blunt tool such as a drift and a hammer,
strike the bottom edge of the cup plug. With the cup
plug rotated, grasp firmly with pliers or other suit-
able tool and remove plug (Fig. 4).CAUTION: Do not drive cup plug into the casting as
restricted cooling can result and cause serious
engine problems.
Thoroughly clean inside of cup plug hole in cylin-
der block or head. Be sure to remove old sealer.
Lightly coat inside of cup plug hole with Mopart
Stud and Bearing Mount. Make certain the new plug
is cleaned of all oil or grease. Using proper drive
plug, drive plug into hole so that the sharp edge of
the plug is at least 0.5 mm (0.020 in.) inside the
lead-in chamfer.
It is not necessary to wait for curing of the sealant.
The cooling system can be refilled and the vehicle
placed in service immediately.
REMOVAL
(1) Disconnect the battery negative cable.
(2) Mark the hinge locations on the hood panel for
alignment reference during installation. Remove the
engine compartment lamp. Remove the hood.
(3) Remove the radiator drain cock and radiator
cap to drain the coolant. DO NOT waste usable cool-
ant. If the solution is clean, drain the coolant into a
clean container for reuse.
(4) Remove the upper radiator hose and coolant
recovery hose.
(5) Remove the lower radiator hose.
(6) Remove upper radiator support retaining bolts
and remove radiator support.
Fig. 3 Cylinder Bore Crosshatch Pattern
1 - CROSSHATCH PATTERN
2 - INTERSECT ANGLE
Fig. 4 Core Hole Plug Removal
1 - CYLINDER BLOCK
2 - REMOVE PLUG WITH PLIERS
3 - STRIKE HERE WITH HAMMER
4 - DRIFT PUNCH
5 - CUP PLUG
WJENGINE - 4.0L 9 - 11
ENGINE - 4.0L (Continued)

WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.
(48) Start the engine, inspect for leaks and correct
the fluid levels, as necessary.
SPECIFICATIONS
ENGINE - 4.0L
DESCRIPTION SPECIFICATION
Engine Type In-line 6 Cylinder
Bore and Stroke 98.4 x 86.69 mm
(3.88 x 3.413 in.)
Displacement 4.0L (242 cu. in.)
Compression Ratio 8.8:1
Firing Order 1±5±3±6±2±4
Lubrication Pressure Feed±Full Flow
Filtration
Cooling System Liquid Cooled±Forced
Circulation
Cylinder Block Cast Iron
Crankshaft Cast Nodular Iron
Cylinder Head Cast Iron
Camshaft Cast Iron
Pistons Aluminum Alloy
Combustion Chamber Dual-Quench
Connecting Rods Cast Malleable Iron
CAMSHAFT
Hydraulic Tappet
ClearanceZero Lash
Bearing Clearance 0.025 to 0.076 mm
(0.001 to 0.003 in.)
DESCRIPTION SPECIFICATION
Bearing Journal Diameter
No. 1 51.54 to 51.56 mm
(2.029 to 2.030 in.)
No. 2 51.28 to 51.31 mm
(2.019 to 2.020 in.)
No. 3 51.03 to 51.05 mm
(2.009 to 2.010 in.)
No. 4 50.78 to 50.80 mm
(1.999 to 2.000 in.)
Base Circle Runout
(MAX)0.03 mm
(0.001 in.)
Valve Lift
Intake 10.350 mm (0.4075 in.)
Exhaust 10.528 mm (0.4145 in.)
Valve Timing
Intake
Opens 12.4É BTDC
Closes 60.9É ABDC
Exhaust
Opens 49.8 BBDC
Closes 29.2É ATDC
Valve Overlap 41.6É
Intake Duration 253.3É
Exhaust Duration 259.É
CRANKSHAFT
End Play 0.038 to 0.165 mm
(0.0015 to 0.0065 in.)
Main Bearing Journal
Diameter
No. 1-6 63.489 to 63.502 mm
(2.4996 to 2.5001 in.)
No. 7 63.449 to 63.487 mm
(2.4980 to 2.4995 in.)
9 - 14 ENGINE - 4.0LWJ
ENGINE - 4.0L (Continued)

DESCRIPTION SPECIFICATION
Main Bearing Journal
Width
No. 1 27.58 to 27.89 mm
(1.086 to 1.098 in.)
No. 3 32.28 to 32.33 mm
(1.271 to 1.273 in.)
No. 2-4-5-6-7 30.02 to 30.18 mm
(1.182 to 1.188 in.)
Main Bearing Clearance 0.03 to 0.06 mm
(0.001 to 0.0025 in.)
Preferred 0.051 mm (0.002 in.)
Connecting Rod Journal
Diameter 53.17 to 53.23 mm
(2.0934 to 2.0955 in.)
Connecting Rod Journal
Width27.18 to 27.33 mm
(1.070 to 1.076 in.)
Out-of-Round (MAX) 0.013 mm (0.0005 in.)
Taper (MAX) 0.013 mm (0.0005 in.)
CYLINDER BLOCK
Deck Height 240.03 to 240.18 mm
(9.450 to 9.456 in.)
Deck Clearance (Below
Block)0.546 mm (0.0215 in.)
Cylinder Bore Diameter
Standard 98.45 to 98.48 mm
(3.8759 to 3.8775 in.)
Taper 0.025 mm (0.001 in.)
Out-ofRound 0.025 mm (0.001 in.)
Tappet Bore Diameter 23.000 to 23.025 mm
(0.9055 to 0.9065 in.)
Flatness 0.03 mm per 25 mm
(0.001 in. per 1 in.)
0.05 mm per 152 mm
(0.002 in. per 6 in.)
Flatness Max. 0.20 mm max. for total
lengthDESCRIPTION SPECIFICATION
(0.008 in. max. for total
length)
Main Bearing Bore
Diameter68.3514 to 68.3768 mm
(2.691 to 2.692 in.)
CONNECTING ROD
Total Weight (Less
Bearing)663 to 671 grams
(23.39 to 23.67 oz.)
Length (Center-to-Center) 155.52 to 155.62 mm
(6.123 to 6.127 in.)
Piston Pin Bore Diameter 23.59 to 23.62 mm
(0.9288 to 0.9298 in.)
Bore (Less Bearings) 56.08 to 56.09 mm
(2.2080 to 2.2085 in.)
Bearing Clearance 0.025 to 0.076 mm
(0.001 to 0.003 in.)
Preferred 0.044 to 0.050 mm
(0.0015 to 0.0020 in.)
Side Clearance 0.25 to 0.48 mm
(0.010 to 0.019 in.)
Twist (Max.) 0.002 mm per mm
(0.002 in. per inch)
Bend (Max.) 0.002 mm per mm
(0.002 in. per inch.)
CYLINDER COMPRESSION PRESSURE
Pressure Range 827 to 1,034 kPa
(120 to 150 psi)
Max. Variation Between
Cylinders 206 kPa (30 psi)
CYLINDER HEAD
Combustion Chamber 55.22 to 58.22 cc
(3.37 to 3.55 cu. in.)
Valve Guide I.D.
(Integral)7.95 to 7.97 mm
(0.313 to 0.314 in.)
WJENGINE - 4.0L 9 - 15
ENGINE - 4.0L (Continued)

DESCRIPTION SPECIFICATION
Valve Stem-to-Guide 0.025 to 0.076 mm
Clearance (0.001 to 0.003 in.)
Valve Seat Angle
Intake 44.5É
Exhaust 44.5É
Valve Seat Width 1.02 to 1.52 mm
(0.040 to 0.060 in.)
Valve Seat Runout 0.064 mm (0.0025 in.)
Flatness 0.03 mm per 25 mm
(0.001 in. per 1 in.)
0.05 mm per 152 mm
(0.002 in. per 6 in.)
Flatness Max. 0.20 mm - max. for total
length
(0.008 in. max. for total
length)
ROCKER ARMS, PUSH RODS & TAPPETS
Rocker Arm Ratio 1.6:1
Push Rod Length 244.856 to 245.364 mm
(Pink) (9.640 to 9.660 in.)
Push Rod Diameter 7.92 to 8.00 mm
(0.312 to 0.315 in.)
Hydraulic Tappet
Diameter22.962 to 22.974 mm
(0.904 to 0.9045 in.)
Tappet-to-Bore Clearance 0.025 to 0.063 mm
(0.001 to 0.0025 in.)
VA LV E S
Valve Length (Overall)
Intake 122.479 to 122.860 mm
(4.822 to 4.837 in.)
Exhaust 122.860 to 123.241 mm
(4.837 to 4.852 in.)
Valve Stem Diameter 7.899 to 7.925 mm
(0.311 to 0.312 in.)
Stem-to-Guide Clearance 0.025 to 0.076 mm
(0.001 to 0.003 in.)DESCRIPTION SPECIFICATION
Valve Head Diameter
Intake 48.387 to 48.641 mm
(1.905 to 1.915 in.)
Exhaust 37.973 to 38.227 mm
(1.495 to 1.505 in.)
Valve Face Angle
Intake 46.5É
Exhaust 46.5É
Tip Refinishing (Max.
Allowable)0.25 mm (0.010 in.)
VALVE SPRINGS
Free Length (Approx.) 47.65 mm (1.876 in.)
Spring Load
Valve Closed 316 to 351 N @ 41.656
mm
(71 to 79 lbf. @ 1.64 in.)
Valve Open 898.6 to 969.7 N @
30.89 mm
(202 to 218 lbf @ 1.216
in.)
Inside Diameter 21.0 mm to 21.51 mm
(0.827 to 0.847 in.)
Installed Height 41.656 mm (1.64 in.)
PISTONS
Weight (Less Pin) 417 to 429 grams
(14.7 to 15.1 oz.)
Piston Pin Bore
(Centerline40.61 to 40.72 mm
to Piston Top) (1.599 to 1.603 in.)
Piston-to-Bore Clearance 0.018 to 0.038 mm
(0.0008 to 0.0015 in.)
Ring Gap Clearance
Top Compression Ring 0.229 to 0.610 mm
(0.0090 to 0.0240 in.)
2nd Compression Ring 0.483 to 0.965 mm
(0.0190 to 0.0380 in.)
Oil Control Steel Rails 0.254 to 1.500 mm
(0.010 to 0.060 in.)
9 - 16 ENGINE - 4.0LWJ
ENGINE - 4.0L (Continued)