engine JEEP CHEROKEE 1994 Service Repair Manual

(3) Install the flywheel or converter drive plate.
New bolts MUST be used when installing the fly-
wheel or converter plate. Tighten the new bolts to 68
Nzm (50 ft. lbs.) torque. Turn the bolts an additional
60É.
CYLINDER BLOCK
Remove the Engine Assembly from the vehicle.
DISASSEMBLY
Refer to the applicable sections for detailed instruc-
tions.
(1) Drain the engine oil. Remove and discard the
oil filter.
(2) Remove the water pump from the cylinder
block.
(3) Remove the distributor from the cylinder block.
(4) Remove the vibration damper.
(5) Remove the timing case cover and lay the cover
upside down.
(6) Position a drift punch into the slot in the back
of the cover and tap the old seal out.
(7) Remove the timing chain bumper.
(8) Remove the oil slinger from crankshaft.
(9) Remove the camshaft retaining bolt and re-
move the sprockets and chain as an assembly.
(10) Remove the camshaft.
(11) Remove the oil pan and gasket.
(12) Remove the timing chain tensioner.
(13) Remove the front and rear oil galley plugs.
(14) Remove the connecting rods and the pistons.
Remove the connecting rod and piston assemblies
through the top of the cylinder bores.
(15) Remove the crankshaft.
CLEANING
Thoroughly clean the oil pan and engine block gas-
ket surfaces.Use compressed air to clean out:
²The galley at the oil filter adaptor hole, the filter
bypass hole (Fig. 9).
²The front and rear oil galley holes (Figs. 10 and
11).
Fig. 8 Replacement of Rear Crankshaft Oil SealFig. 9 Oil Filter Adaptor Hole
Fig. 10 Front Oil Galley Hole
Fig. 11 Rear Oil Galley Hole
J2.5L ENGINE 9 - 45

²The feed holes for the crankshaft main bearings.
Once the block has been completely cleaned, apply
Loctite PST pipe sealant with Teflon 592 to the
threads of the front and rear oil galley plugs.
Tighten the plugs to 41 Nzm (30 ft. lbs.) torque.
INSPECTIONÐCYLINDER BORE
(1) Use a bore gauge to measure each cylinder bore
diameter (Fig. 12). If a bore gauge is not available,
use an inside micrometer.
(2) Measure the cylinder bore diameter crosswise
to the cylinder block near the top of the bore. Repeat
the measurement near the bottom of the bore.
(3) Determine taper by subtracting the smaller di-
ameter from the larger diameter.
(4) Rotate measuring device 120É and repeat steps
above. Finally, rotate the device another 120É and re-
peat measurements.
(5) Determine out-of-roundness by comparing the
difference between each 120É measurement.(6) If cylinder bore taper does not exceed 0.025 mm
(0.001 inch) and out-of-roundness does not exceed
0.025 mm (0.001 inch), the cylinder bore can be
honed. If the cylinder bore taper or out-of-round con-
dition exceeds these maximum limits, the cylinder
must be bored and then honed to accept an oversize
piston. A slight amount of taper always exists in the
cylinder bore after the engine has been in use for a
period of time.
HONINGÐCYLINDER BORE
The honing operation should be closely coordinated
with the fitting of pistons and rings. This will ensure
specified clearances are maintained.
Refer to Standard Service Procedures in the begin-
ning of this Group for the proper honing of cylinder
bores.
ASSEMBLY
Refer to the applicable sections for detailed instruc-
tions.
(1) Install the crankshaft.
(2) Install the connecting rods and the pistons
through the top of the cylinder bores.
(3) Install the front and rear oil galley plugs.
(4) Install the timing chain tensioner.
(5) Install the camshaft.
(6) Install the sprockets and chain as an assembly.
(7) Install the oil slinger to the crankshaft.
(8) Install the timing chain bumper.
(9) Install the timing case cover seal.
(10) Install the timing case cover.
(11) Install the oil pan gasket and oil pan.
(12) Install the vibration damper.
(13) Install the water pump. Tighten the mounting
bolts to 31 Nzm (270 in. lbs.) torque.
(14) Remove the distributor from the cylinder
block.
(15) Lubricate the oil filter seal with clean engine
oil. Tighten oil filter to 18 Nzm (13 ft. lbs.) torque.
(16) Install the engine into the vehicle.
(17) Fill the engine with clean lubrication oil (re-
fer to Group 0, Lubrication and Maintenance).
(18) Fill the cooling system (refer to Group 7, Cool-
ing System for the proper procedures).
Fig. 12 Cylinder Bore Measurement
9 - 46 2.5L ENGINEJ

SPECIFICATIONS
ENGINE SPECIFICATIONS
J2.5L ENGINE 9 - 47

ENGINE SPECIFICATIONS (CONT.)
9 - 48 2.5L ENGINEJ

ENGINE SPECIFICATIONS (CONT.)
TORQUE SPECIFICATIONS
J2.5L ENGINE 9 - 49

4.0L ENGINE SERVICE PROCEDURES
INDEX
page page
Camshaft............................... 69
Camshaft Pin Replacement................. 71
Crankshaft Main Bearings.................. 80
Cylinder Block........................... 85
Engine AssemblyÐXJ Vehicles.............. 54
Engine AssemblyÐYJ Vehicles.............. 57
Engine Cylinder Head..................... 60
Engine Cylinder Head Cover................ 59
Engine MountÐRear...................... 52
Engine MountsÐFront..................... 51
General Information....................... 50
Hydraulic Tappets........................ 65
Oil Pan ................................ 72Oil Pump............................... 73
Pistons and Connecting Rods............... 74
Rear Main Oil Seals...................... 84
Rocker Arms............................ 59
Specifications........................... 87
Timing Case Cover....................... 67
Timing Case Cover Oil Seal Replacement...... 67
Timing Chain and Sprockets................ 68
Valve Springs and Oil Seals................ 62
Valve Timing............................ 66
Valves and Valve Springs.................. 63
Vibration Damper........................ 67
GENERAL INFORMATION
The 4.0 Liter (242 CID) six-cylinder engine is an
In-line, lightweight, overhead valve engine (Fig. 1).
This engine is designed for unleaded fuel.
The engine cylinder head has dual quench-type
combustion chambers that create turbulence and fast
burning of the air/fuel mixture. This results in good
fuel economy.
The cylinders are numbered 1 through 6 from front
to rear. The firing order is 1-5-3-6-2-4 (Fig. 2).The crankshaft rotation is clockwise, when viewed
from the front of the engine. The crankshaft rotates
within seven main bearings. The camshaft rotates
within four bearings.
BUILD DATE CODE
The engine Build Date Code is located on a ma-
chined surface on the right side of the cylinder block
between the No.2 and No.3 cylinders (Fig. 3).
The digits of the code identify:
(1) 1st DigitÐThe year (4 = 1994).
(2) 2nd & 3rd DigitsÐThe month (01 - 12).
(3) 4th & 5th DigitsÐThe engine type/fuel system/
compression ratio (MX = A 4.0 Liter (242 CID) 8.7:1
compression ratio engine with a multi-point fuel in-
jection system).
(4) 6th & 7th DigitsÐThe day of engine build (01 -
31).
FOR EXAMPLE:Code * 401MX12 * identifies a
4.0 liter (242 CID) engine with a multi-point fuel in-
jection system, 8.7:1 compression ratio and built on
January 12, 1994.
Fig. 2 Engine Firing Order
Fig. 1 Engine Description
9 - 50 4.0L ENGINEJ

OVERSIZE AND UNDERSIZE COMPONENT
CODES
Some engines may be built with oversize or under-
size components such as:
²Oversize cylinder bores.
²Oversize camshaft bearing bores.
²Undersize crankshaft main bearing journals.
²Undersize connecting rod journals.
These engines are identified by a letter code (Fig.
4) stamped on a boss between the ignition coil and
the distributor (Fig. 5).
ENGINE MOUNTSÐFRONT
The front mounts support the engine at each side.
These supports are made of resilient rubber.
REMOVAL
(1) Disconnect negative cable from battery.
(2) Raise the vehicle.
(3) Support the engine.
(4) Remove the nut from the through bolt (Figs. 6
and 7). DO NOT remove the through bolt.
(5) Remove the retaining bolts/nuts from the sup-
port cushions (Figs. 6 and 7).
(6) Remove the through bolt.
(7) Remove the support cushions.
INSTALLATION
(1) If the engine support bracket was removed, po-
sition the bracket onto the block and install the at-
taching bolts (Figs. 6 and 7). Tighten the engine
support bracket bolts:
²XJ VehiclesÐ61 Nzm (45 ft. lbs.) torque.
²YJ VehiclesÐ62 Nzm (46 ft. lbs.) torque.
(2) ON XJ VEHICLES, if the support cushion
bracket was removed, position the bracket onto the
lower front sill (Fig. 8). Install support cushion
bracket bolts/nuts. Tighten the bolts to 54 Nzm (40 ft.
lbs.) torque. Tighten the nuts to 41 Nzm (30 ft. lbs.)
torque.
(3) Place the support cushion into position on the
support cushion bracket (Figs. 6 and 7). Install and
tighten the bolts/nuts:
²XJ VehiclesÐ41 Nzm (30 ft. lbs.) torque.
²YJ VehiclesÐ52 Nzm (38 ft. lbs.) torque.
Fig. 3 Build Date Code Location
Fig. 4 Oversize and Undersize Component Codes
Fig. 5 Oversize and Undersize Component Code
Location
J4.0L ENGINE 9 - 51

(4) Install the through bolt and the retaining nut
(Figs. 6 and 7). Tighten the through bolt nut:
²XJ VehiclesÐ65 Nzm (48 ft. lbs.) torque.
²YJ VehiclesÐ69 Nzm (51 ft. lbs.) torque.
(5) Remove the engine support.
(6) Lower the vehicle.
(7) Connect negative cable to battery.
ENGINE MOUNTÐREAR
A resilient rubber cushion supports the transmis-
sion at the rear between the transmission extension
housing and the rear support crossmember or skid
plate.
REMOVALÐXJ VEHICLES
(1) Disconnect negative cable from battery.
(2) Raise the vehicle and support the transmission.
(3) Remove the nuts holding the support cushion to
the crossmember (Figs. 9 and 10). Remove the cross-
member.
(4)MANUAL TRANSMISSION (Fig. 9):
(a) Remove the support cushion nuts and remove
the cushion.
(b) Remove the transmission support bracket
bolts and remove the bracket from the transmis-
sion.
(5)AUTOMATIC TRANSMISSION (Fig. 10):
Fig. 6 Front MountsÐXJ Vehicles
Fig. 7 Front MountsÐYJ Vehicles
Fig. 8 Support Cushion BracketÐXJ Vehicles
9 - 52 4.0L ENGINEJ

(a) Remove the support cushion bolts and remove
the cushion and the support bracket from the
transmission (4WD) or from the adaptor bracket
(2WD).
(b) On 2WD vehicles, remove the bolts holding
the transmission support adaptor bracket to the
transmission (Fig. 10). Remove the adaptor
bracket.
INSTALLATIONÐXJ VEHICLES
(1)MANUAL TRANSMISSION:
(a) Install the transmission support bracket to
the transmission. Install the bolts and tighten to
46 Nzm (34 ft. lbs.) torque.
(b) Install the support cushion to the support
bracket. Install the nuts and tighten to 75 Nzm (55
ft. lbs.) torque.
(2)AUTOMATIC TRANSMISSION:
(a) On 2WD vehicles, position the transmission
support adaptor bracket to the transmission. Install
the bolts and tighten to 75 Nzm (55 ft. lbs.) torque.
(b) Position the transmission support bracket
and support cushion to the adaptor bracket (2WD)
or the transmission (4WD). Install the bolts and
tighten to 75 Nzm (55 ft. lbs.) torque.
(3) Position the crossmember onto the support
cushion studs. Install the stud nuts and tighten to 22
Nzm (192 in. lbs) torque.
(4) Install crossmember-to-sill bolts and tighten to
41 Nzm (30 ft. lbs.) torque.
(5) Remove the transmission support.
(6) Lower the vehicle.
(7) Connect negative cable to battery.
REMOVALÐYJ VEHICLES
(1) Disconnect negative cable from battery.
(2) Raise the vehicle and support the transmission.
(3)MANUAL TRANSMISSION (Fig. 11):
(a) Remove the nuts holding the support cushion
and the insulator to the skid plate. Remove the up-
per nut from the insulator stud.
(b) Remove the skid plate bolts and the skid
plate. Remove the insulator stud assembly.
(c) Remove the support cushion nuts. Remove the
support cushion from the torque arm bracket.
(d) Remove the torque arm bracket bolts and re-
move the bracket from the transmission.
(4)AUTOMATIC TRANSMISSION (Fig. 12):
(a) Remove the nuts holding the support cushion
to the skid plate. Remove the skid plate.
(b) Remove the bolts and nuts holding the sup-
port cushion to the torque arm bracket. Remove
the support cushion.
(c) Remove the bolts holding the torque arm
bracket to the transmission. Remove the torque
arm bracket.
INSTALLATIONÐYJ VEHICLES
(1)MANUAL TRANSMISSION:
Fig. 9 Rear MountÐXJ Vehicles (Manual
Transmission)
Fig. 10 Rear MountÐXJ Vehicles (Automatic
Transmission)
J4.0L ENGINE 9 - 53

(a) Position the torque arm bracket to the trans-
mission. Install the bolts and tighten to 54 Nzm (40
ft. lbs.) torque.
(b) Position the support cushion onto the torque
arm bracket. Install the nuts and tighten to 54
Nzm (40 ft. lbs.) torque.
(c) Position the insulator stud assembly and up-
per nut (Fig. 11). Position the skid plate to the
studs of the support cushion and the insulator stud
(Fig. 11). Install the support cushion stud nuts and
tighten to 54 Nzm (40 ft. lbs.) torque. Install the
lower stud nut and tighten the upper and lower in-
sulator stud nuts to 41 Nzm (30 ft. lbs.) torque.
(2)AUTOMATIC TRANSMISSION:
(a) Position the torque arm bracket to the trans-
mission. Install the bolts and tighten to 54 Nzm (40
ft. lbs.) torque.
(b) Position the support cushion onto the torque
arm bracket. Install the bolts/nuts and tighten to
54 Nzm (40 ft. lbs.) torque.
(c) Position the skid plate to the studs of the sup-
port cushion and install the nuts. Tighten the sup-
port cushion stud nuts to 54 Nzm (40 ft. lbs.)
torque.
(3) Install the skid plate bolts to the sill and
tighten to 88 Nzm (65 ft. lbs.) torque.(4) Remove the transmission support.
(5) Lower the vehicle.
(6) Connect negative cable to battery.
ENGINE ASSEMBLYÐXJ VEHICLES
REMOVAL
(1) Disconnect the battery cables. Remove the bat-
tery.
(2) Mark the hinge locations on the hood panel for
alignment reference during installation. Remove the
engine compartment lamp. Remove the hood.
WARNING: THE COOLANT IN A RECENTLY OPER-
ATED ENGINE IS HOT AND PRESSURIZED. USE
CARE TO PREVENT SCALDING BY HOT COOLANT.
CAREFULLY RELEASE THE PRESSURE BEFORE
REMOVING THE RADIATOR DRAIN COCK AND
CAP.
(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 lower radiator hose.
(5) Remove the upper radiator hose and coolant re-
covery hose (Fig. 13).
Fig. 11 Rear MountÐYJ Vehicles (Manual
Transmission)Fig. 12 Rear MountÐYJ Vehicles (Automatic
Transmission)
9 - 54 4.0L ENGINEJ