2003 JEEP GRAND CHEROKEE seat

(1) A result of restricted fluid flow through the
main and/or auxiliary cooler. This condition is usu-
ally the result of a faulty or improperly installed
drainback valve, a damaged main cooler, or severe
restrictions in the coolers and lines caused by debris
or kinked lines.
(2) Heavy duty operation with a vehicle not prop-
erly equipped for this type of operation. Trailer tow-
ing or similar high load operation will overheat the
transmission fluid if the vehicle is improperly
equipped. Such vehicles should have an auxiliary
transmission fluid cooler, a heavy duty cooling sys-
tem, and the engine/axle ratio combination needed to
handle heavy loads.
DIAGNOSIS AND TESTING - FLUID
CONTAMINATION
Transmission fluid contamination is generally a
result of:
²adding incorrect fluid
²failure to clean dipstick and fill tube when
checking level
²engine coolant entering the fluid
²internal failure that generates debris
²overheat that generates sludge (fluid break-
down)
²failure to reverse flush cooler and lines after
repair
²failure to replace contaminated converter after
repair
The use of non-recommended fluids can result in
transmission failure. The usual results are erratic
shifts, slippage, abnormal wear and eventual failure
due to fluid breakdown and sludge formation. Avoid
this condition by using recommended fluids only.
The dipstick cap and fill tube should be wiped
clean before checking fluid level. Dirt, grease and
other foreign material on the cap and tube could fall
into the tube if not removed beforehand. Take the
time to wipe the cap and tube clean before withdraw-
ing the dipstick.
Engine coolant in the transmission fluid is gener-
ally caused by a cooler malfunction. The only remedy
is to replace the radiator as the cooler in the radiator
is not a serviceable part. If coolant has circulated
through the transmission, an overhaul is necessary.
The transmission cooler and lines should be
reverse flushed whenever a malfunction generates
sludge and/or debris. The torque converter should
also be replaced at the same time.
Failure to flush the cooler and lines will result in
recontamination. Flushing applies to auxiliary coolers
as well. The torque converter should also be replaced
whenever a failure generates sludge and debris. This
is necessary because normal converter flushing proce-
dures will not remove all contaminants.
STANDARD PROCEDURE
STANDARD PROCEDURE - FLUID LEVEL
CHECK
Low fluid level can cause a variety of conditions
because it allows the pump to take in air along with
the fluid. As in any hydraulic system, air bubbles
make the fluid spongy, therefore, pressures will be
low and build up slowly.
Improper filling can also raise the fluid level too
high. When the transmssion has too much fluid, the
geartrain churns up foam and cause the same condi-
tions which occur with a low fluid level.
In either case, air bubbles can cause overheating
and/or fluid oxidation, and varnishing. This can
interfere with normal valve, clutch, and accumulator
operation. Foaming can also result in fluid escaping
from the transmission vent where it may be mis-
taken for a leak.
After the fluid has been checked, seat the dipstick
fully to seal out water and dirt.
The transmission has a dipstick to check oil level.
It is located on the right side of the engine. Be sure
to wipe all dirt from dipstick handle before removing.
Fluid level is checked with the engine running at
curb idle speed, the transmission in NEUTRAL and
the transmission fluid at normal operating tempera-
ture.The engine should be running at idle
speed for at least one minute, with the vehicle
on level ground.
The transmission fluid level can be checked two
ways.
PROCEDURE ONE
(1) Transmission fluid must be at normal operat-
ing temperature for accurate fluid level check. Drive
vehicle if necessary to bring fluid temperature up to
normal hot operating temperature of 82ÉC (180ÉF).
(2) Position vehicle on level surface.
(3) Start and run engine at curb idle speed.
(4) Apply parking brakes.
(5) Shift transmission momentarily into all gear
ranges. Then shift transmission back to NEUTRAL.
(6) Clean top of filler tube and dipstick to keep
dirt from entering tube.
(7) Remove dipstick (Fig. 87) and check fluid level
as follows:
(a) Correct acceptable level is in crosshatch area.
(b) Correct maximum level is to MAX arrow
mark.
(c) Incorrect level is at or below MIN line.
(d) If fluid is low, add only enough MopartAT F
+4, type 9602, to restore correct level. Do not over-
fill.
21 - 70 AUTOMATIC TRANSMISSION - 42REWJ
FLUID AND FILTER (Continued)

OPERATION
To apply the clutch, pressure is applied between
the clutch retainer and piston. The fluid pressure is
provided by the oil pump, transferred through the
control valves and passageways, and enters the
clutch through the hub of the reaction shaft support.
With pressure applied between the clutch retainer
and piston, the piston moves away from the clutch
retainer and compresses the clutch pack. This action
applies the clutch pack, allowing torque to flow
through the input shaft into the driving discs, and
into the clutch plates and pressure plate that are
lugged to the clutch retainer. The waved snap-ring is
used to cushion the application of the clutch pack.
When pressure is released from the piston, the
spring returns the piston to its fully released position
and disengages the clutch. The release spring also
helps to cushion the application of the clutch assem-
bly. When the clutch is in the process of being
released by the release spring, fluid flows through a
vent and one-way ball-check-valve located in the
clutch retainer. The check-valve is needed to elimi-
nate the possibility of plate drag caused by centrifu-
gal force acting on the residual fluid trapped in the
clutch piston retainer.
DISASSEMBLY
(1) Remove waved snap-ring and remove pressure
plate, clutch plates and clutch discs (Fig. 92).
(2) Compress clutch piston spring with Compressor
Tool C-3575-A (Fig. 93). Be sure legs of tool are
seated squarely on spring retainer before compress-
ing spring.
(3) Remove retainer snap-ring and remove com-
pressor tool.
(4) Remove spring retainer and clutch spring. Note
position of retainer on spring for assembly reference.
(5) Remove clutch piston from clutch retainer.
Remove piston by rotating it up and out of retainer.
(6) Remove seals from clutch retainer piston bore
and clutch retainer hub. Discard both seals as they
are not reusable.
INSPECTION
Inspect the front clutch components. Replace the
clutch discs if warped, worn, scored, burned or
charred, or if the facing is flaking off. Replace the
steel plates if heavily scored, warped, or broken. Be
sure the driving lugs on the plates are in good con-
dition. The lugs must not be bent, cracked or dam-
aged in any way.
Replace the clutch spring and spring retainer if
either is distorted, warped or broken.Check the lug grooves in the clutch retainer. The
steel plates should slide freely in the slots. Replace
the retainer if the grooves are worn or damaged.
Check action of the check ball in the retainer (Fig.
94). The ball must move freely and not stick.
NOTE: Inspect the clutch retainer bushings care-
fully (Fig. 95). The retainer bushings are NOT ser-
viceable. It will be necessary to replace the retainer
if either bushing is scored, or worn.
Inspect the piston and retainer seal surfaces for
nicks or scratches. Minor scratches can be removed
with crocus cloth. However, replace the piston and/or
retainer if the seal surfaces are seriously scored.
ASSEMBLY
NOTE: The 42RE transmission uses four plates and
discs for the front clutch.
(1) Soak clutch discs in transmission fluid while
assembling other clutch parts.
(2) Install new seals in the clutch retainer lower
groove and on outer diameter of the retainer hub. Be
sure lip of each seal faces interior of clutch retainer.
(3) Lubricate lips of the retainer seals with liberal
quantity of MopartDoor Ease. Then lubricate
retainer hub, bore and piston with light coat of trans-
mission fluid.
(4) Install clutch piston in retainer (Fig. 96). Use
twisting motion to seat piston in bottom of retainer.
CAUTION: Never push the clutch piston straight in.
This will fold the seals over causing leakage and
clutch slip.
(5) Position spring in clutch piston (Fig. 97).
(6) Position spring retainer on top of piston spring.
Make sure retainer is properly installed (Fig. 92).
(7) Compress piston spring and retainer with Com-
pressor Tool C-3575-A (Fig. 93). Then install new
snap-ring to secure spring retainer and spring.
(8) Install clutch plates and discs (Fig. 92). Install
steel plate then disc until all plates and discs are
installed. The front clutch uses 4 clutch discs and
plates in a 42RE transmission.
(9) Install pressure plate and waved snap-ring
(Fig. 92).
Clearance should be 1.70 to 3.40 mm (0.067 to
0.134 in.). If clearance is incorrect, clutch discs,
plates, pressure plates and snap-ring may have to be
changed.
21 - 74 AUTOMATIC TRANSMISSION - 42REWJ
FRONT CLUTCH (Continued)

(12) Install new oil seal in pump with Special Tool
C-4193 and Tool Handle C-4171 (Fig. 122). Be sure
seal lip faces inward.
(13) Install new seal ring around pump housing.
Be sure seal is properly seated in groove.
(14) Lubricate lip of pump oil seal and O-ring seal
with transmission fluid.
OUTPUT SHAFT FRONT
BEARING
REMOVAL
(1) Remove overdrive unit from the vehicle.
(2) Remove overdrive geartrain from housing.
(3) Remove snap-ring holding output shaft front
bearing to overdrive geartrain. (Fig. 123).
(4) Pull bearing from output shaft.
INSTALLATION
(1) Place replacement bearing in position on
geartrain with locating retainer groove toward the
rear.
(2) Push bearing onto shaft until the snap-ring
groove is visible.
(3) Install snap-ring to hold bearing onto output
shaft.
(4) Install overdrive geartrain into housing.
(5) Install overdrive unit in vehicle.
OUTPUT SHAFT REAR
BEARING
REMOVAL
(1) Remove overdrive unit from the vehicle. (Refer
to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC/
OVERDRIVE - REMOVAL)
(2) Remove overdrive geartrain from housing.
(3) Remove snap-ring holding output shaft rear
bearing into overdrive housing (Fig. 124).
(4) Using a suitable driver inserted through the
rear end of housing, drive bearing from housing.
INSTALLATION
(1) Place replacement bearing in position in hous-
ing.
(2) Using a suitable driver, drive bearing into
housing until the snap-ring groove is visible.
(3) Install snap-ring to hold bearing into housing
(Fig. 124).
(4) Install overdrive geartrain into housing.
(5) Install overdrive unit in vehicle.
Fig. 122 Pump Oil Seal Installation
1 - PUMP BODY
2 - PUMP SEAL
3 - SPECIAL TOOL C-4193
Fig. 123 Output Shaft Front Bearing
1 - OUTPUT SHAFT FRONT BEARING
2 - SNAP-RING
3 - OUTPUT SHAFT
4 - GROOVE TO REAR
5 - OVERDRIVE GEARTRAIN
Fig. 124 Output Shaft Rear Bearing
1 - OUTPUT SHAFT REAR BEARING
2 - OVERDRIVE HOUSING
3 - SNAP-RING
WJAUTOMATIC TRANSMISSION - 42RE 21 - 85
OIL PUMP (Continued)

(10) Remove snap-ring that secures annulus gear
on output shaft (Fig. 153). Use two screwdrivers to
unseat and work snap-ring out of groove as shown.(11) Remove annulus gear from output shaft (Fig.
154). Use rawhide or plastic mallet to tap gear off
shaft.
Fig. 151 Clutch Drum Outer Retaining Ring Removal
1 - OUTER RETAINING RING
Fig. 152 Marking Annulus Gear And Output Shaft
For Assembly Alignment
1 - OUTPUT SHAFT
2 - HAMMER
3 - PUNCH
Fig. 153 Annulus Gear Snap-Ring Removal
1 - OUTPUT SHAFT
2 - ANNULUS GEAR
3 - SNAP-RING
Fig. 154 Annulus Gear Removal
1 - OUTPUT SHAFT
2 - ANNULUS GEAR
21 - 94 AUTOMATIC TRANSMISSION - 42REWJ
OVERDRIVE UNIT (Continued)

(4) Align and install clutch drum on annulus gear
(Fig. 157). Be sure drum is engaged in annulus gear
lugs.
(5) Install clutch drum outer retaining ring (Fig.
157).
(6) Slide clutch drum forward and install inner
retaining ring (Fig. 158).
(7) Install rear bearing and snap-ring on output
shaft (Fig. 159). Be sure locating ring groove in bear-
ing is toward rear.(8) Install overrunning clutch on hub (Fig. 160).
Note that clutch only fits one-way. Shoulder on clutch
should seat in small recess at edge of hub.
(9) Install thrust bearing on overrunning clutch
hub. Use generous amount of petroleum jelly to hold
bearing in place for installation. Bearing fits one-way
only. Be sure bearing is seated squarely against hub.
Reinstall bearing if it does not seat squarely.
(10) Install overrunning clutch in output shaft
(Fig. 161). Insert snap-ring pliers in hub splines.
Expand pliers to grip hub. Then install assembly
with counterclockwise, twisting motion.
(11) Install planetary gear in annulus gear (Fig.
162). Be sure planetary pinions are fully seated in
annulus gear before proceeding.
(12) Coat planetary thrust bearing and bearing
contact surface of spring plate with generous amount
of petroleum jelly. This will help hold bearing in
place during installation.
Fig. 156 Annulus Gear Installation
1 - SNAP-RING
2 - OUTPUT SHAFT FRONT BEARING
3 - ANNULUS GEAR
Fig. 157 Clutch Drum And Outer Retaining Ring
Installation
1 - ANNULUS GEAR
2 - OUTER SNAP-RING
3 - CLUTCH DRUM
Fig. 158 Clutch Drum Inner Retaining Ring
Installation
1 - ANNULUS GEAR
2 - INNER SNAP-RING
3 - CLUTCH DRUM
Fig. 159 Rear Bearing And Snap-Ring Installation
1 - REAR BEARING
2 - SNAP-RING
21 - 96 AUTOMATIC TRANSMISSION - 42REWJ
OVERDRIVE UNIT (Continued)

(13) Install planetary thrust bearing on sun gear
(Fig. 163). Slide bearing onto gear and seat it against
spring plate as shown. Bearing fits one-way only. If it
does not seat squarely against spring plate, remove
and reposition bearing.
(14) Install assembled sun gear, spring plate and
thrust bearing (Fig. 164). Be sure sun gear and
thrust bearing are fully seated before proceeding.
Fig. 160 Assembling Overrunning Clutch And Hub
1 - CLUTCH HUB
2 - OVERRUNNING CLUTCH
Fig. 161 Overrunning Clutch Installation
1 - CLUTCH DRUM
2 - OVERRUNNING CLUTCH ASSEMBLY
3 - EXPANDING-TYPE SNAP-RING PLIERS
4 - CLUTCH DRUM
5 - ANNULUS GEAR
6 - OVERRUNNING CLUTCH ASSEMBLY SEATED IN OUTPUT
SHAFT
Fig. 162 Planetary Gear Installation
1 - PLANETARY GEAR
2 - ANNULUS GEAR
Fig. 163 Planetary Thrust Bearing Installation
1 - SPRING PLATE
2 - PLANETARY THRUST BEARING
3 - SUN GEAR
WJAUTOMATIC TRANSMISSION - 42RE 21 - 97
OVERDRIVE UNIT (Continued)

(15) Mount assembled output shaft, annulus gear,
and clutch drum in shop press. Direct clutch spring,
hub and clutch pack are easier to install with assem-
bly mounted in press.
(16) Align splines in hubs of planetary gear and
overrunning clutch with Alignment tool 6227-2 (Fig.
165). Insert tool through sun gear and into splines of
both hubs. Be sure alignment tool is fully seated
before proceeding.
(17) Install direct clutch spring (Fig. 166). Be sure
spring is properly seated on spring plate.
NOTE: The 42RE transmission has 6 direct clutch
discs and 5 clutch plates.
(18) Assemble and install direct clutch pack on
hub as follows:
(a) Assemble clutch pack components (Fig. 167).
(b) Install direct clutch reaction plate on clutch
hub first. Note that one side of reaction plate is
counterbored. Be sure this side faces rearward.
Splines at rear of hub are raised slightly. Counter-
bore in plate fits over raised splines. Plate should
be flush with this end of hub (Fig. 168).
(c) Install first clutch disc followed by a steel
plate until all discs and plates have been installed.
(d) Install pressure plate. This is last clutch
pack item to be installed. Be sure plate is installed
with shoulder side facing upward (Fig. 169).
(19) Install clutch hub and clutch pack on direct
clutch spring (Fig. 170). Be sure hub is started on
sun gear splines before proceeding.
Fig. 164 Sun Gear Installation
1 - SUN GEAR AND SPRING PLATE ASSEMBLY
Fig. 165 Alignment Tool Installation
1 - SPECIAL TOOL 6227-2
2 - PRESS PLATES
3 - ASSEMBLED DRUM AND ANNULUS GEAR
4 - SUN GEAR
Fig. 166 Direct Clutch Spring Installation
1 - SPECIAL TOOL 6227-2
2 - DIRECT CLUTCH SPRING
3 - CLUTCH HUB
4 - PRESS PLATES
21 - 98 AUTOMATIC TRANSMISSION - 42REWJ
OVERDRIVE UNIT (Continued)

WARNING: THE NEXT STEP IN GEARTRAIN
ASSEMBLY INVOLVES COMPRESSING THE DIRECT
CLUTCH HUB AND SPRING. IT IS EXTREMELY
IMPORTANT THAT PROPER EQUIPMENT BE USED
TO COMPRESS THE SPRING AS SPRING FORCE IS
APPROXIMATELY 830 POUNDS. USE COMPRES-
SOR TOOL C-6227-1 AND A HYDRAULIC-TYPE
SHOP PRESS WITH A MINIMUM RAM TRAVEL OF 6
INCHES. THE PRESS MUST ALSO HAVE A BED
THAT CAN BE ADJUSTED UP OR DOWN AS
REQUIRED. RELEASE CLUTCH SPRING TENSION
SLOWLY AND COMPLETELY TO AVOID PERSONAL
INJURY.
(20) Position Compressor Tool 6227-1 on clutch
hub.
(21) Compress clutch hub and spring just enough
to place tension on hub and hold it in place.
(22) Slowly compress clutch hub and spring. Com-
press spring and hub only enough to expose ring
grooves for clutch pack snap ring and clutch hub
retaining ring.
(23) Realign clutch pack on hub and seat clutch
discs and plates in clutch drum.
(24) Install direct clutch pack snap-ring (Fig. 171).
Be very sure snap-ring is fully seated in clutch drum
ring groove.
(25) Install clutch hub retaining ring (Fig. 172). Be
very sure retaining ring is fully seated in sun gear
ring groove.
(26) Slowly release press ram, remove compressor
tools and remove geartrain assembly.
GEAR CASE
(1) Position park pawl and spring in case and
install park pawl shaft. Verify that end of spring
with 90É bend is hooked to pawl and straight end of
spring is seated against case.
(2) Install pawl shaft retaining bolt. Tighten bolt
to 27 N´m (20 ft. lbs.) torque.
(3) Install park lock reaction plug. Note that plug
has locating pin at rear (Fig. 173). Be sure pin is
seated in hole in case before installing snap-ring.
(4) Install reaction plug snap-ring (Fig. 174). Com-
press snap ring only enough for installation; do not
distort it.
Fig. 170 Direct Clutch
1 - CLUTCH HUB
2 - DIRECT CLUTCH PACK
3 - CLUTCH DRUM
Fig. 171 Direct Clutch Pack Snap-Ring Installation
1 - SPECIAL TOOL 6227-1
2 - DIRECT CLUTCH PACK SNAP-RING
Fig. 172 Clutch Hub Retaining Ring Installation
1 - SPECIAL TOOL 6227-1
2 - CLUTCH HUB RETAINING RING
21 - 100 AUTOMATIC TRANSMISSION - 42REWJ
OVERDRIVE UNIT (Continued)