2003 JEEP GRAND CHEROKEE engine pressure

(9) Lower the engine until it is properly located on
the engine mounts.
(10) Install the through bolts and tighten the nuts.
(11) Lower the jack stand and remove the piece of
wood.
(12) Install the engine flywheel and transmission
torque converter housing access cover.
(13) Install the engine starter motor. (Refer to 8 -
ELECTRICAL/STARTING/STARTER MOTOR -
INSTALLATION).
(14) Connect the exhaust pipe to the hanger and to
the engine exhaust manifold.
(15) Install transmission oil cooling lines (if
equipped) and oxygen sensor wiring supports that
attach to the oil pan studs.
(16) Install the oil pan drain plug (Fig. 81).
Tighten the plug to 34 N´m (25 ft. lbs.) torque.
(17) Lower the vehicle.
(18) Connect negative cable to battery.
(19) Fill the oil pan with engine oil to the specified
level.
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.
(20) Start the engine and inspect for leaks.
ENGINE OIL PRESSURE
SENSOR
DESCRIPTION
The 3±wire, solid-state engine oil pressure sensor
(sending unit) is located in an engine oil pressure
gallery.
OPERATION
The oil pressure sensor uses three circuits. They
are:
²A 5±volt power supply from the Powertrain Con-
trol Module (PCM)
²A sensor ground through the PCM's sensor
return
²A signal to the PCM relating to engine oil pres-
sure
The oil pressure sensor has a 3±wire electrical
function very much like the Manifold Absolute Pres-
sure (MAP) sensor. Meaning different pressures
relate to different output voltages.
A 5±volt supply is sent to the sensor from the PCM
to power up the sensor. The sensor returns a voltage
signal back to the PCM relating to engine oil pres-
sure. This signal is then transferred (bussed) to theinstrument panel on either a CCD or PCI bus circuit
(depending on vehicle line) to operate the oil pressure
gauge and the check gauges lamp. Ground for the
sensor is provided by the PCM through a low-noise
sensor return.
OIL PUMP
REMOVAL
A gear-type oil pump is mounted at the underside
of the cylinder block opposite the No.4 main bearing.
(1) Drain the engine oil.
(2) Remove the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - REMOVAL).
(3) Remove the pump-to-cylinder block attaching
bolts. Remove the pump assembly with gasket (Fig.
82).
CAUTION: If the oil pump is not to be serviced, DO
NOT disturb position of oil inlet tube and strainer
assembly in pump body. If the tube is moved within
the pump body, a replacement tube and strainer
assembly must be installed to assure an airtight
seal.
Fig. 82 Oil Pump Assembly
1 - OIL FILTER ADAPTOR
2 - BLOCK
3 - GASKET
4 - OIL INLET TUBE
5 - OIL PUMP
6 - STRAINER ASSEMBLY
7 - ATTACHING BOLTS
9 - 56 ENGINE - 4.0LWJ
OIL PAN (Continued)

INSTALLATION
A gear-type oil pump is mounted at the underside
of the cylinder block opposite the No.4 main bearing.
(1) Install the oil pump on the cylinder block using
a replacement gasket. Tighten the bolts to 23 N´m
(17 ft. lbs.) torque.
(2) Install the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - INSTALLATION).
(3) Fill the oil pan with oil to the specified level.
INTAKE MANIFOLD
DESCRIPTION
The intake manifold (Fig. 83) is made of cast alu-
minum and uses eleven bolts to mount to the cylin-
der head. This mounting style improves sealing and
reduces the chance of leaks.
DIAGNOSIS AND TESTING - INTAKE
MANIFOLD LEAKAGE
An intake manifold air leak is characterized by
lower than normal manifold vacuum. Also, one or
more cylinders may not be functioning.
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 THE FAN.
DO NOT WEAR LOOSE CLOTHING.
(1) Start the engine.
(2) Spray a small stream of water at the suspected
leak area.
(3) If a change in RPM is observed the area of the
suspected leak has been found.
(4) Repair as required.
REMOVAL
NOTE: THE ENGINE INTAKE AND EXHAUST MANI-
FOLD MUST BE REMOVED AND INSTALLED
TOGETHER. THE MANIFOLDS USE A COMMON
GASKET AT THE CYLINDER HEAD.
(1) Disconnect the battery negative cable.
(2) Remove air cleaner inlet hose from the resona-
tor assembly.
(3) Remove the air cleaner assembly.
(4) Remove the throttle cable, vehicle speed control
cable (if equipped) and the transmission line pres-
sure cable (Refer to 21 - TRANSMISSION/TRANS-
AXLE/AUTOMATIC - AW4/THROTTLE VALVE
CABLE - REMOVAL).
(5) Disconnect the following electrical connections
and secure their harness out of the way:
²Throttle Position Sensor
²Idle Air Control Motor
²Coolant Temperature Sensor (at thermostat
housing)
²Intake Air Temperature Sensor
²Oxygen Sensor
²Crank Position Sensor
²Six (6) Fuel Injector Connectors
²Manifold Absolute Pressure (MAP) Sensor.
(6) Disconnect HVAC, and Brake Booster vacuum
supply hoses at the intake manifold.
(7) Perform the fuel pressure release procedure.
(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY -
STANDARD PROCEDURE).
(8) Disconnect and remove the fuel system supply
line from the fuel rail assembly.
(9) Remove the accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(10) Remove the power steering pump from the
intake manifold and set aside.
(11) Raise the vehicle.
(12) Disconnect the exhaust pipes from the engine
exhaust manifolds.
(13) Lower the vehicle.
(14) Remove the intake manifold and exhaust
manifold bolts and manifolds (Fig. 84).
INSTALLATION
If the manifold is being replaced, ensure all the fit-
ting, etc. are transferred to the replacement mani-
fold.
(1) Install a new engine exhaust/intake manifold
gasket over the alignment dowels on the cylinder
head.
(2) Position the engine exhaust manifolds to the
cylinder head. Install fastener Number 3 and finger
tighten at this time (Fig. 84).
Fig. 83 Intake Manifold 4.0L Engine
WJENGINE - 4.0L 9 - 57
OIL PUMP (Continued)

(3) Install intake manifold on the cylinder head
dowels.
(4) Install washer and fastener Numbers 1, 2, 4, 5,
8, 9, 10 and 11 (Fig. 84).
(5) Install washer and fastener Numbers 6 and 7
(Fig. 84).
(6) Tighten the fasteners in sequence and to the
specified torque (Fig. 84).
²Fastener Numbers 1 through 5ÐTighten to 33
N´m (24 ft. lbs.) torque.
²Fastener Numbers 6 and 7ÐTighten to 31 N´m
(23 ft. lbs.) torque.
²Fastener Numbers 8 through 11ÐTighten to 33
N´m (24 ft. lbs.) torque.
(7) Install the power steering pump to the intake
manifold.
(8) Install the accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION).
(9) Install the fuel system supply line to the fuel
rail assembly.
(10) Connect all electrical connections on the
intake manifold.
(11) Connect the vacuum hoses previously
removed.
(12) Install throttle cable, vehicle speed control
cable (if equipped).
(13) Install the transmission line pressure cable (if
equipped) (Refer to 21 - TRANSMISSION/TRANS-
AXLE/AUTOMATIC - AW4/THROTTLE VALVE
CABLE - INSTALLATION).
(14) Install air cleaner assembly.
(15) Connect air inlet hose to the resonator assem-
bly.
(16) Raise the vehicle.
(17) Connect the exhaust pipes to the engine
exhaust manifolds. Tighten the bolts to 31 N´m (23
ft. lbs.)
(18) Lower the vehicle.(19) Connect the battery negative cable.
(20) Start the engine and check for leaks.
EXHAUST MANIFOLD
DESCRIPTION
The two exhaust manifolds (Fig. 85) are log style
and are made of high silicon molybdenum cast iron.
The exhaust manifolds share a common gasket with
the intake manifold. The exhaust manifolds also
incorporate ball flange outlets for improved sealing
and strain free connections.
REMOVAL
The intake and engine exhaust manifolds on the
4.0L engine must be removed together. The manifolds
use a common gasket at the cylinder head.
(Refer to 9 - ENGINE/MANIFOLDS/INTAKE
MANIFOLD - REMOVAL).
INSTALLATION
(1) The exhaust manifold and the intake manifold
must be installed together using a common gasket.
(2) (Refer to 9 - ENGINE/MANIFOLDS/INTAKE
MANIFOLD - INSTALLATION).
TIMING BELT / CHAIN
COVER(S)
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove the vibration damper (Refer to 9 -
ENGINE/ENGINE BLOCK/VIBRATION DAMPER -
REMOVAL).
(3) Remove the fan, hub assembly and fan shroud
(Refer to 7 - COOLING/ENGINE/RADIATOR FAN -
REMOVAL).
(4) Remove the accessory drive brackets that are
attached to the timing case cover.
(5) Remove the A/C compressor (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/A/C
COMPRESSOR - REMOVAL) (if equipped) and gen-
erator bracket assembly from the engine cylinder
head and move to one side.
(6) Remove the oil pan-to-timing case cover bolts
and timing case cover-to-cylinder block bolts.
(7) Remove the timing case cover and gasket from
the engine.
(8) Pry the crankshaft oil seal from the front of the
timing case cover (Fig. 86).
INSTALLATION
Clean the timing case cover, oil pan and cylinder
block gasket surfaces.
Fig. 84 Intake and Exhaust Manifolds Installation
9 - 58 ENGINE - 4.0LWJ
INTAKE MANIFOLD (Continued)

ENGINE - 4.7L
TABLE OF CONTENTS
page page
ENGINE - 4.7L
DESCRIPTIONÐ4.7L ENGINE.............63
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION...........64
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - PERFORMANCE...........65
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - MECHANICAL.............66
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - LUBRICATION.............67
DIAGNOSIS AND TESTING - CYLINDER
COMPRESSION PRESSURE.............68
DIAGNOSIS AND TESTING - CYLINDER
COMBUSTION PRESSURE LEAKAGE......69
STANDARD PROCEDURE
STANDARD PROCEDURE - REPAIR
DAMAGED OR WORN THREADS.........70
STANDARD PROCEDURE - FORM-IN-
PLACE GASKETS AND SEALERS.........70
STANDARD PROCEDURE - ENGINE
GASKET SURFACE PREPARATION........70
STANDARD PROCEDURE - ENGINE CORE
AND OIL GALLERY PLUGS..............71
REMOVAL.............................71
INSTALLATION.........................73
SPECIFICATIONS
4.7L ENGINE.........................74
SPECIFICATIONS - 4.7L H.O. ENGINE.....77
TORQUE............................79
SPECIAL TOOLS
4.7L ENGINE.........................80
AIR CLEANER ELEMENT
REMOVAL - 4.7L........................83
INSTALLATION - 4.7L....................83
AIR CLEANER HOUSING
REMOVAL - 4.7L........................84
INSTALLATION - 4.7L....................84
CYLINDER HEAD - LEFT
DESCRIPTION
DESCRIPTION - CYLINDER HEAD........84
DESCRIPTION - VALVE GUIDES..........84
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - HYDRAULIC
LASH ADJUSTER.....................84
DIAGNOSIS AND TESTINGÐCYLINDER
HEAD GASKET.......................85
REMOVAL.............................85
CLEANING............................86
INSPECTION..........................87INSTALLATION.........................87
CAMSHAFT(S) - LEFT
DESCRIPTION.........................88
REMOVAL.............................89
INSTALLATION.........................90
CYLINDER HEAD COVER(S) - LEFT
DESCRIPTION.........................93
REMOVAL - LEFT SIDE..................93
CLEANING............................93
INSTALLATIONÐLEFT SIDE...............93
INTAKE/EXHAUST VALVES & SEATS
DESCRIPTION.........................94
STANDARD PROCEDUREÐREFACING......94
REMOVAL.............................94
INSTALLATION.........................95
ROCKER ARM / ADJUSTER ASSEMBLY
DESCRIPTION.........................96
REMOVAL.............................96
INSTALLATION.........................96
VALVE SPRINGS
DESCRIPTION.........................97
VALVE STEM SEALS
DESCRIPTION.........................97
CYLINDER HEAD - RIGHT
DESCRIPTION
DESCRIPTION - CYLINDER HEAD........97
DESCRIPTION - VALVE GUIDES..........97
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTINGÐCYLINDER
HEAD GASKET.......................97
DIAGNOSIS AND TESTING - HYDRAULIC
LASH ADJUSTER.....................98
REMOVAL.............................98
CLEANING............................99
INSPECTION..........................99
INSTALLATION.........................99
CAMSHAFT(S) - RIGHT
DESCRIPTION........................100
REMOVAL............................100
INSTALLATION........................102
CYLINDER HEAD COVER(S) - RIGHT
DESCRIPTION........................104
REMOVAL - RIGHT SIDE................104
CLEANING...........................104
INSTALLATION - RIGHT SIDE.............104
INTAKE/EXHAUST VALVES & SEATS
DESCRIPTION........................104
STANDARD PROCEDUREÐREFACING.....105
REMOVAL............................105
INSTALLATION........................106
WJENGINE - 4.7L 9 - 61

ROCKER ARM / ADJUSTER ASSEMBLY
DESCRIPTION........................107
REMOVAL............................107
INSTALLATION........................107
VALVE SPRINGS
DESCRIPTION........................108
VALVE STEM SEALS
DESCRIPTION........................108
ENGINE BLOCK
DESCRIPTION........................108
STANDARD PROCEDUREÐCYLINDER BORE
HONING...........................108
CLEANING...........................109
INSPECTION.........................109
CONNECTING ROD BEARINGS
STANDARD PROCEDURE - CONNECTING
ROD BEARING FITTING...............109
CRANKSHAFT
DESCRIPTION........................111
STANDARD PROCEDURE - MEASURING
CRANKSHAFT END PLAY..............111
REMOVAL............................112
INSPECTION..........................112
INSTALLATION........................112
CRANKSHAFT MAIN BEARINGS
STANDARD PROCEDUREÐCRANKSHAFT
MAIN BEARING - FITTING..............114
INSPECTION..........................115
CRANKSHAFT OIL SEAL - FRONT
REMOVAL............................115
INSTALLATION........................116
CRANKSHAFT OIL SEAL - REAR
REMOVAL............................117
INSTALLATION........................117
FLEX PLATE
REMOVAL............................118
INSTALLATION........................118
PISTON & CONNECTING ROD
DESCRIPTION........................118
STANDARD PROCEDUREÐPISTON FITTING . 118
REMOVAL............................118
CLEANING...........................119
INSPECTION..........................119
INSTALLATION........................120
PISTON RINGS
STANDARD PROCEDURE - PISTON RING
FITTING............................121
VIBRATION DAMPER
REMOVAL............................122
INSTALLATION........................123
STRUCTURAL COVER
DESCRIPTION........................124
OPERATION..........................124
REMOVAL............................124
INSTALLATION........................124
FRONT MOUNT
REMOVAL............................124INSTALLATION........................125
REAR MOUNT
REMOVAL............................125
INSTALLATION........................126
LUBRICATION
DESCRIPTION........................126
OPERATION..........................126
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTINGÐENGINE OIL
PRESSURE.........................128
DIAGNOSIS AND TESTINGÐREAR SEAL
AREA LEAKS........................128
DIAGNOSIS AND TESTINGÐENGINE OIL
LEAK..............................129
OIL
STANDARD PROCEDURE - ENGINE OIL....130
OIL FILTER
REMOVAL............................131
INSTALLATION........................132
OIL PAN
DESCRIPTION........................132
REMOVAL............................132
CLEANING...........................132
INSPECTION.........................132
INSTALLATION........................132
OIL PRESSURE SENSOR/SWITCH
DESCRIPTION........................133
OPERATION..........................133
REMOVAL............................133
INSTALLATION........................133
OIL PUMP
REMOVAL............................134
DISASSEMBLY........................134
CLEANING...........................134
INSPECTION.........................134
ASSEMBLY...........................135
INSTALLATION........................135
INTAKE MANIFOLD
DESCRIPTION........................136
DIAGNOSIS AND TESTINGÐINTAKE
MANIFOLD LEAKAGE.................136
REMOVAL............................136
CLEANING...........................137
INSPECTION.........................137
INSTALLATION........................137
EXHAUST MANIFOLD - LEFT
DESCRIPTION........................138
REMOVAL............................138
CLEANING...........................138
INSPECTION.........................138
INSTALLATION........................138
EXHAUST MANIFOLD - RIGHT
DESCRIPTION........................139
REMOVAL............................139
CLEANING...........................140
INSPECTION.........................141
INSTALLATION........................141
9 - 62 ENGINE - 4.7LWJ

DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION
Engine diagnosis is helpful in determining the
causes of malfunctions not detected and remedied by
routine maintenance.
These malfunctions may be classified as either per-
formance (e.g., engine idles rough and stalls) or
mechanical (e.g., a strange noise).
(Refer to 9 - ENGINE - DIAGNOSIS AND TEST-
ING)ÐPERFORMANCE and (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)ÐMECHANICAL for
possible causes and corrections of malfunctions.
(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY -
DIAGNOSIS AND TESTING) and (Refer to 14 -
FUEL SYSTEM/FUEL INJECTION - DIAGNOSIS
AND TESTING) for the fuel system diagnosis.
Additional tests and diagnostic procedures may be
necessary for specific engine malfunctions that can
not be isolated with the Service Diagnosis charts.
Information concerning additional tests and diagno-
sis is provided within the following diagnosis:
²Cylinder Compression Pressure Test (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
²Cylinder Combustion Pressure Leakage Test
(Refer to 9 - ENGINE - DIAGNOSIS AND TEST-
ING).
²Engine Cylinder Head Gasket Failure Diagnosis
(Refer to 9 - ENGINE/CYLINDER HEAD - DIAGNO-
SIS AND TESTING).
²Intake Manifold Leakage Diagnosis (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
DIAGNOSIS AND TESTING).
Fig. 1 Engine Identification Location
1 - VEHICLE VIN NUMBER LOCATION
2 - CYLINDER BLOCK RIGHT HAND SIDE
3 - CYLINDER BORE #2
9 - 64 ENGINE - 4.7LWJ
ENGINE - 4.7L (Continued)

CONDITION POSSIBLE CAUSE CORRECTION
1. ENGINE MISSES ON
ACCELERATION1. Spark plugs dirty or incorrectly
gapped.1. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/SPARK PLUG -
CLEANING).
2. Dirt in fuel system. 2. Clean fuel system.
3. Burned, warped or pitted valves. 3. Replcae as necessary.
4. Faulty coil. 4. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/IGNITION COIL -
REMOVAL).
1. ENGINE MISSES AT HIGH
SPEED1. Spark plugs dirty or incorrectly
gapped.1. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/SPARK PLUG -
CLEANING).
2. Faulty coil. 2. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/IGNITION COIL -
REMOVAL).
3. Dirt or water in fuel system. 3. Clean system and replace fuel filter.
DIAGNOSIS AND TESTING - ENGINE DIAGNOSIS - MECHANICAL
CONDITION POSSIBLE CAUSES CORRECTIONS
NOISY VALVES 1. High or low oil level in crankcase. 1. (Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
SPECIFICATIONS).
2. Thin or diluted oil. 2. Change oil and filter.
3. Low oil pressure. 3. Check oil pump, if Ok, check rod
and main bearings for excessive wear.
4. Dirt in lash adjusters. 4. Replace as necessary.
5. Worn rocker arms. 5. Replace as necessary.
6. Worn lash adjusters 6. Replace as necessary.
7. Worn valve guides. 7. (Refer to 9 - ENGINE/CYLINDER
HEAD/INTAKE/EXHAUST VALVES &
SEATS - STANDARD PROCEDURE).
8. Excessive runout of valve seats
on valve faces.8. Service valves and valve seats.
(Refer to 9 - ENGINE/CYLINDER
HEAD/INTAKE/EXHAUST VALVES &
SEATS - STANDARD PROCEDURE).
CONNECTING ROD NOISE 1. Insufficient oil supply. 1. (Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
SPECIFICATIONS).
2. Low oil pressure. 2. Check oil pump, if Ok, check rod
and main bearings for excessive wear.
3. Thin or diluted oil. 3. Change oil and filter.
4. Excessive bearing clearance. 4. Replace as necessary.
5. Connecting rod journal out-of-
round.5. Service or replace crankshaft.
6. Misaligned connecting rods. 6. Replace bent connecting rods.
9 - 66 ENGINE - 4.7LWJ
ENGINE - 4.7L (Continued)

CONDITION POSSIBLE CAUSES CORRECTIONS
MAIN BEARING NOISE 1. Insufficient oil supply. 1. (Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
SPECIFICATIONS).
2. Low oil pressure. 2. Check oil pump, if Ok, check rod
and main bearings for excessive wear.
3. Thin or diluted oil. 3. Change oil and filter.
4. Excessive bearing clearance. 4. Replace as necessary.
5. Excessive end play. 5. Check thrust washers for wear.
6. Crankshaft journal out-of round. 6. Service or replace crankshaft.
7. Loose flywheel or torque
converter.7. Tighten to correct torque
DIAGNOSIS AND TESTING - ENGINE DIAGNOSIS - LUBRICATION
CONDITION POSSIBLE CAUSES CORRECTION
OIL LEAKS 1. Gaskets and O-Rings. 1.
(a) Misaligned or damaged. (a) Replace as necessary.
(b) Loose fasteners, broken or
porous metal parts.(b) Tighten fasteners, Repair or
replace metal parts.
2. Crankshaft rear seal 2. Replace as necessary (Refer to 9 -
ENGINE/ENGINE BLOCK/
CRANKSHAFT OIL SEAL - REAR -
REMOVAL).
3. Crankshaft seal flange.
Scratched, nicked or grooved.3. Polish or replace crankshaft.
4. Oil pan flange cracked. 4. Replace oil pan (Refer to 9 -
ENGINE/LUBRICATION/OIL PAN -
REMOVAL).
5. Timing chain cover seal, damaged
or misaligned.5. Replace seal (Refer to 9 -
ENGINE/ENGINE BLOCK/
CRANKSHAFT OIL SEAL - FRONT -
REMOVAL).
6. Scratched or damaged vibration
damper hub.6. Polish or replace damper.
WJENGINE - 4.7L 9 - 67
ENGINE - 4.7L (Continued)