2003 JEEP GRAND CHEROKEE Lock cylinder

HYDRAULIC LIFTERS
DESCRIPTION
Valve lash is controlled by hydraulic tappets
located inside the cylinder block, in tappet bores
above the camshaft.
REMOVAL
NOTE: Retain all the components in the same order
as removed.
(1) Remove the engine cylinder head(Refer to 9 -
ENGINE/CYLINDER HEAD - REMOVAL).
(2) Remove the push rods.
(3) Remove the tappets through the push rod open-
ings in the cylinder block with a Hydraulic Valve
Tappet Removal/Installation Tool (Fig. 53).
CLEANING
Clean each tappet assembly in cleaning solvent to
remove all varnish, gum and sludge deposits.
INSPECTION
Inspect for indications of scuffing on the side and
base of each tappet body.
Inspect each tappet base for concave wear with a
straightedge positioned across the base. If the base is
concave, the corresponding lobe on the camshaft is
also worn. Replace the camshaft and tappets.
After cleaning and inspection, test each tappet for
specified leak-down rate tolerance to ensure zero-lash
operation (Fig. 54).
Swing the weighted arm of the hydraulic valve tap-
pet tester away from the ram of the Leak-Down
Tester.
(1) Place a 7.925-7.950 mm (0.312-0.313 inch)
diameter ball bearing on the plunger cap of the tap-
pet.(2) Lift the ram and position the tappet (with the
ball bearing) inside the tester cup.
(3) Lower the ram, then adjust the nose of the ram
until it contacts the ball bearing. DO NOT tighten
the hex nut on the ram.
(4) Fill the tester cup with hydraulic valve tappet
test oil until the tappet is completely submerged.
(5) Swing the weighted arm onto the push rod and
pump the tappet plunger up and down to remove air.
When the air bubbles cease, swing the weighted arm
away and allow the plunger to rise to the normal
position.
(6) Adjust the nose of the ram to align the pointer
with the SET mark on the scale of the tester and
tighten the hex nut.
(7) Slowly swing the weighted arm onto the push
rod.
(8) Rotate the cup by turning the handle at the
base of the tester clockwise one revolution every 2
seconds.
(9) Observe the leak-down time interval from the
instant the pointer aligns with the START mark on
the scale until the pointer aligns with the 0.125
mark. A normally functioning tappet will require
20-110 seconds to leak-down. Discard tappets with
leak-down time interval not within this specification.
INSTALLATION
Retain all the components in the same order as
removed.
Fig. 53 HYDRAULIC VALVE TAPPET REMOVAL -
4.0L
1 - HYDRAULIC TAPPET REMOVAL TOOL
2 - CYLINDER BLOCK
Fig. 54 Leak-Down Tester
1 - POINTER
2 - WEIGHTED ARM
3 - RAM
4 - CUP
5 - HANDLE
6 - PUSH ROD
WJENGINE - 4.0L 9 - 43

PISTON SIZE CHART
CYLINDER BORE SIZE PISTON LETTER SIZE
98.438 - 98.448 mm
(3.8755 - 3.8759 in.)A
98.448 - 98.458 mm
(3.8759 - 3.8763 in.)B
98.458 - 98.468 mm
(3.8763 - 3.8767 in.)C
98.468 - 98.478 mm
(3.8767 - 3.8771 in.)D
98.478 - 98.488 mm
(3.8771 - 3.8775 in.)E
98.488 - 98.498 mm
(3.8775 - 3.8779 in.)F
REMOVAL
(1) Remove the engine cylinder head cover. (Refer
to 9 - ENGINE/CYLINDER HEAD/CYLINDER
HEAD COVER(S) - REMOVAL).
(2) Remove the rocker arms, bridges and pivots.
(3) Remove the push rods.
(4) Remove the engine cylinder head. (Refer to 9 -
ENGINE/CYLINDER HEAD - REMOVAL).
(5) Position the pistons one at a time near the bot-
tom of the stroke. Use a ridge reamer to remove theridge from the top end of the cylinder walls. Use a
protective cloth to collect the cuttings.
(6) Raise the vehicle.
(7) Drain the engine oil.
(8) Remove the oil pan and gasket. (Refer to 9 -
ENGINE/LUBRICATION/OIL PAN - REMOVAL).
(9) Remove main bearing cap brace (Fig. 58).
(10) Remove the connecting rod bearing caps and
inserts. Mark the caps and rods with the cylinder
bore location. The connecting rods and caps are
stamped with a two letter combination (Fig. 59).
Fig. 57 Bore Gauge
1 - FRONT
2 - BORE GAUGE
3 - CYLINDER BORE
4 - 49.5 MM (1-15/16 in.)
Fig. 58 Main Bearings Caps and Brace
1 - BLOCK
2 - MAIN BEARING CAP BRACE
Fig. 59 Stamped Connecting Rods and Caps
1 - CONNECTING ROD CAP
2 - CONNECTING ROD
WJENGINE - 4.0L 9 - 45
PISTON & CONNECTING ROD (Continued)

(11) Lower the vehicle until it is about 2 feet from
the floor.
CAUTION: Ensure that the connecting rod bolts DO
NOT scratch the crankshaft journals or cylinder
walls. Short pieces of rubber hose, slipped over the
rod bolts will provide protection during removal.
(12) Have an assistant push the piston and con-
necting rod assemblies up and through the top of the
cylinder bores (Fig. 60).
INSTALLATION
(1) Clean the cylinder bores thoroughly. Apply a
light film of clean engine oil to the bores with a clean
lint-free cloth.
(2) Install the piston rings on the pistons if
removed (Refer to 9 - ENGINE/ENGINE BLOCK/
PISTON RINGS - STANDARD PROCEDURE).
(3) Lubricate the piston and rings with clean
engine oil.
CAUTION: Ensure that connecting rod bolts DO
NOT scratch the crankshaft journals or cylinder
walls. Short pieces of rubber hose slipped over the
connecting rod bolts will provide protection during
installation.(4) Use a piston ring compressor to install the con-
necting rod and piston assemblies through the top of
the cylinder bores (Fig. 61).
(5) Ensure the arrow on the piston top points to
the front of the engine (Fig. 61).
(6) Raise the vehicle.
(7) Each bearing insert is fitted to its respective
journal to obtain the specified clearance between the
bearing and the journal. In production, the select fit
is obtained by using various-sized, color-coded bear-
ing inserts as listed in the Connecting Rod Bearing
Fitting Chart. The color code appears on the edge of
the bearing insert. The size is not stamped on inserts
used for production of engines.
(8) The rod journal is identified during the engine
production by a color-coded paint mark on the adja-
cent cheek or counterweight toward the flange (rear)
end of the crankshaft. The color codes used to indi-
cate journal sizes are listed in the Connecting Rod
Bearing Fitting Chart.
(9) When required, upper and lower bearing
inserts of different sizes may be used as a pair (refer
to Connecting Rod Bearing Fitting Chart). A stan-
dard size insert is sometimes used in combination
with a 0.025 mm (0.001 inch) undersize insert to
reduce clearance 0.013 mm (0.0005 inch).
CAUTION: DO NOT intermix bearing caps. Each
connecting rod and bearing cap are stamped with
the cylinder number. The stamp is located on a
machined surface adjacent to the oil squirt hole
that faces the camshaft side of the cylinder block.
(10) Install the connecting rod bearing caps and
inserts in the same positions as removed.
CAUTION: Verify that the oil squirt holes in the rods
face the camshaft and that the arrows on the pis-
tons face the front of the engine.
(11) Install main bearing cap brace (Fig. 58).
Tighten nuts to 47 N´m (35 ft. lbs.).
Fig. 60 Removal of Connecting Rod and Piston
Assembly
1 - PISTON
2 - CONNECTING ROD
3 - BLOCK
Fig. 61 Rod and Piston Assembly Installation
9 - 46 ENGINE - 4.0LWJ
PISTON & CONNECTING ROD (Continued)

crankshaft is drilled internally to pass oil from the
main bearing journals (except number 4 main bear-
ing journal) to the connecting rod journals. Each con-
necting rod bearing cap has a small squirt hole, oil
passes through the squirt hole and is thrown off as
the rod rotates. This oil throwoff lubricates the cam-
shaft lobes, distributor drive gear, cylinder walls, and
piston pins.
The hydraulic valve tappets receive oil directly
from the main oil gallery. Oil is provided to the cam-
shaft bearing through galleries. The front camshaft
bearing journal passes oil through the camshaft
sprocket to the timing chain. Oil drains back to the
oil pan under the number one main bearing cap.
The oil supply for the rocker arms and bridged
pivot assemblies is provided by the hydraulic valve
tappets which pass oil through hollow push rods to a
hole in the corresponding rocker arm. Oil from the
rocker arm lubricates the valve train components,
then passes down through the push rod guide holes
in the cylinder head past the valve tappet area, and
returns to the oil pan (Fig. 73).
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE OIL
PRESSURE
(1) Disconnect connector and remove oil pressure
sending unit.
(2) Install Oil Pressure Line and Gauge Tool
C-3292 or equivalent. Start engine and record pres-
sure. (Refer to 9 - ENGINE - SPECIFICATIONS) for
the correct pressures.
DIAGNOSIS AND TESTING - ENGINE OIL LEAK
Begin with a thorough visual inspection of the
engine, particularly at the area of the suspected leak.
If an oil leak source is not readily identifiable, the
following steps should be followed:
(1) Do not clean or degrease the engine at this
time because some solvents may cause rubber to
swell, temporarily stopping the leak.
(2) Add an oil soluble dye (use as recommended by
manufacturer). Start the engine and let idle for
approximately 15 minutes. Check the oil dipstick to
make sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light.
(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified,
repair per service manual instructions.
(4) If dye is not observed, drive the vehicle at var-
ious speeds for approximately 24km (15 miles), and
repeat inspection.If the oil leak source is not pos-itively identified at this time, proceed with the air
leak detection test method.
Air Leak Detection Test Method
(1) Disconnect the breather cap to air cleaner hose
at the breather cap end. Cap or plug breather cap
nipple.
(2) Remove the CCV valve from the cylinder head
cover. Cap or plug the CCV valve grommet.
(3) Attach an air hose with pressure gauge and
regulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to
more than 20.6 kpa (3 PSI) of test pressure.
(4) Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus-
pected source. Adjust the regulator to the suitable
test pressure that provide the best bubbles which
will pinpoint the leak source. If the oil leak is
detected and identified, repair per service informa-
tion procedures.
(5) If the leakage occurs at the rear oil seal area,
INSPECTION FOR REAR SEAL AREA LEAKS .
(6) If no leaks are detected, turn off the air supply
and remove the air hose and all plugs and caps.
Install the CCV valve and breather cap hose.
(7) Clean the oil off the suspect oil leak area using
a suitable solvent. Drive the vehicle at various
speeds approximately 24 km (15 miles). Inspect the
engine for signs of an oil leak by using a black light.
INSPECTION FOR REAR 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, pressurize the crank-
case as outlined in the, Inspection (Engine oil Leaks
in general)
CAUTION: Do not exceed 20.6 kPa (3 psi).
WJENGINE - 4.0L 9 - 51
LUBRICATION (Continued)

All Jeep engines are equipped with a high quality
full-flow, throw-away type oil filter. DaimlerChrysler
Corporation recommends a Mopartor equivalent oil
filter be used.
(1) Position a drain pan under the oil filter.
(2) Using a suitable oil filter wrench loosen filter.
(3) Rotate the oil filter counterclockwise to remove
it from the cylinder block oil filter boss or filter
adapter housing (Fig. 75).
(4) When filter separates from adapter nipple, tip
gasket end upward to minimize oil spill. Remove fil-
ter from vehicle.
(5) Make sure old gasket comes off with oil filter.
With a wiping cloth, clean the gasket sealing surface
(Fig. 76) of oil and grime.
INSTALLATION
(1) Lightly lubricate oil filter gasket with engine
oil or chassis grease.
(2) Thread filter onto adapter nipple. When gasket
makes contact with sealing surface, (Fig. 76) hand
tighten filter one full turn, do not over tighten.
(3) Add oil, verify crankcase oil level and start
engine. Inspect for oil leaks.
OIL PAN
DESCRIPTION
The oil pan is made of stamped steel. The oil pan
gasket is a one piece steel backbone silicone coated
gasket (Fig. 77).
REMOVAL
(1) Disconnect negative cable from battery.
(2) Raise the vehicle.
(3) Remove the oil pan drain plug and drain the
engine oil.
(4) Disconnect the exhaust pipe at the exhaust
manifold.
(5) Disconnect the exhaust hanger at the catalytic
converter and lower the pipe.
(6) Remove the starter motor. (Refer to 8 - ELEC-
TRICAL/STARTING/STARTER MOTOR - REMOV-
AL).
(7) Remove the engine flywheel and transmission
torque converter housing access cover.
(8) If equipped with an oil level sensor, disconnect
the sensor.
(9) Position a jack stand directly under the engine
vibration damper.
Fig. 75 Oil FilterÐ4.0L Engine
1 - CYLINDER BLOCK
2 - ADAPTER
3 - OIL FILTER
Fig. 76 Oil Filter Sealing SurfaceÐTypical
1 - SEALING SURFACE
2 - RUBBER GASKET
3 - OIL FILTER
Fig. 77 Oil Pan
1 - OIL PAN
2 - OIL PAN DRAIN PLUG
9 - 54 ENGINE - 4.0LWJ
OIL FILTER (Continued)

(10) Place a piece of wood (2 x 2) between the jack
stand and the engine vibration damper.
(11) Remove the engine mount through bolts.
(12) Using the jack stand, raise the engine until
adequate clearance is obtained to remove the oil pan.
(13) Remove transmission oil cooling lines (if
equipped) and oxygen sensor wiring supports that
are attached to the oil pan studs.
(14) Remove the oil pan bolts and studs. Carefully
slide the oil pan and gasket to the rear. If equipped
with an oil level sensor, take care not to damage the
sensor.
INSTALLATION
(1) Clean the block and pan gasket surfaces.
(2) Fabricate 4 alignment dowels from 1 1/2 x 1/4
inch bolts. Cut the head off the bolts and cut a slot
into the top of the dowel. This will allow easier
installation and removal with a screwdriver (Fig. 78).
(3) Install two dowels in the timing case cover.
Install the other two dowels in the cylinder block
(Fig. 79).
(4) Apply MopartSilicone Rubber Adhesive Seal-
ant on cylinder block to rear main bearing cap cor-
ners and cylinder block to front cover joints (four
places) (Fig. 80).
(5) Slide the one-piece gasket over the dowels and
onto the block and timing case cover.
(6) Position the oil pan over the dowels and onto
the gasket. If equipped with an oil level sensor, take
care not to damage the sensor.
(7) Install the 1/4 inch oil pan bolts. Tighten these
bolts to 9.5 N´m (84 in. lbs.) torque. Install the 5/16
inch oil pan bolts (Fig. 81). Tighten these bolts to 15
N´m (132 in. lbs.) torque.
(8) Remove the dowels. Install the remaining 1/4
inch oil pan bolts. Tighten these bolts to 9.5 N´m (84
in. lbs.) torque.
Fig. 78 Fabrication of Alignment Dowels
1 - 1/488ý 1 1/288BOLT
2 - DOWEL
3 - SLOT
Fig. 79 Position of Dowels in Cylinder Block
1 - DOWEL HOLES
2 - CYLINDER BLOCK
3 - 5/1688HOLES
4 - 5/1688HOLES
Fig. 80 Oil Pan Sealer Location
1 - SEALER LOCATIONS
Fig. 81 Position of 5/16 inch Oil Pan Bolts
1 - OIL PAN
2 - OIL PAN DRAIN PLUG
WJENGINE - 4.0L 9 - 55
OIL PAN (Continued)

(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)