front differential cover JEEP GRAND CHEROKEE 2002 WJ / 2.G User Guide

TRANSFER CASE - NV242
TABLE OF CONTENTS
page page
TRANSFER CASE - NV242
DESCRIPTION........................280
OPERATION..........................281
DIAGNOSIS AND TESTING - TRANSFER
CASE - NV242.......................281
REMOVAL............................282
DISASSEMBLY........................282
CLEANING...........................292
INSPECTION.........................293
ASSEMBLY...........................295
INSTALLATION........................307
SPECIFICATIONS
TRANSFER CASE - NV242.............308
SPECIAL TOOLS
TRANSFER CASE - NV242.............308
FLUID
STANDARD PROCEDURE - FLUID DRAIN/
REFILL............................310FRONT OUTPUT SHAFT SEAL
REMOVAL............................310
INSTALLATION........................310
POSITION SENSOR
DESCRIPTION........................311
OPERATION..........................311
REMOVAL............................312
INSTALLATION........................312
REAR RETAINER BUSHING AND SEAL -
NV242HD
REMOVAL............................312
INSTALLATION........................312
SHIFT CABLE
REMOVAL............................313
INSTALLATION........................313
TRANSFER CASE - NV242
DESCRIPTION
The NV242 is a full transfer case (Fig. 1). It pro-
vides full time 2-wheel, or 4-wheel drive operation.
A differential in the transfer case is used to control
torque transfer to the front and rear axles. A low
range gear provides increased low speed torque capa-
bility for off road operation. The low range provides a
2.72:1 reduction ratio.
The geartrain is mounted in two aluminum case
halves attached with bolts. The mainshaft front and
rear bearings are mounted in aluminum retainer
housings bolted to the case halves.
TRANSFER CASE IDENTIFICATION
Two versions of the NV242 are used in the WJ
vehicles, NV242LD and NV242HD. The two transfer
cases can be distinguished from one another by the
rear output shaft retainer. The NV242LD uses a rub-
ber boot to cover the rear output shaft, while the
NV242HD uses a cast aluminum housing. Other than
this difference, the two transfer cases are serviced
the same.
A circular ID tag is attached to the rear case of
each transfer case (Fig. 2). The ID tag provides the
transfer case model number, assembly number, serial
number, and low range ratio.The transfer case serial number also represents
the date of build.
SHIFT MECHANISM
Operating ranges are selected with a lever in the
floor mounted shifter assembly. The shift lever is con-
nected to the transfer case range lever by an adjust-
able cable. A straight line shift pattern is used.
Range positions are marked on the shifter bezel.
Fig. 1 NV242 Transfer Case
21 - 280 TRANSFER CASE - NV242WJ

(a) If the refrigerant system fails to reach the
specified vacuum, the system has a leak that must
be corrected. (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING - DIAGNOSIS AND
TESTING - REFRIGERANT SYSTEM LEAKS)
(b) If the refrigerant system maintains the spec-
ified vacuum for five minutes, restart the vacuum
pump, open the suction and discharge valves and
evacuate the system for an additional ten minutes.
(3) Close all of the valves, and turn off the charg-
ing station vacuum pump.
(4) The refrigerant system is now ready to be
charged with R-134a refrigerant. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
STANDARD PROCEDURE - REFRIGERANT
SYSTEM CHARGE
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
After the refrigerant system has been tested for
leaks and evacuated, a refrigerant charge can be
injected into the system. (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - SPECIFICA-
TIONS - CHARGE CAPACITY)
A R-134a refrigerant recovery/recycling/charging
station that meets SAE Standard J2210 must be
used to charge the refrigerant system with R-134a
refrigerant. Refer to the operating instructions sup-
plied by the equipment manufacturer for proper care
and use of this equipment.
PARTIAL CHARGE METHOD
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
The partial charge method is used to add a partial
charge to a refrigerant system that is low on refrig-
erant. To perform this procedure the evaporator inlet
and outlet tube temperatures are measured. The
temperature difference is measured with a tempera-
ture meter with one or two clamp-on thermocouple
probes. The difference between the evaporator inlet
and outlet tube temperatures will determine the
amount of refrigerant needed.Before adding a partial refrigerant charge, check
for refrigerant system leaks. (Refer to 24 - HEATING
& AIR CONDITIONING/PLUMBING - DIAGNOSIS
AND TESTING - REFRIGERANT SYSTEM LEAKS)
If a leak is found, make the necessary repairs before
attempting a full or partial refrigerant charge.
(1) Attach a manifold gauge set to the refrigerant
system service ports.
(2) Attach the two clamp-on thermocouple probes
to the inlet and outlet tubes of the evaporator coil.
²If a single thermocouple probe is used, attach
the probe to the evaporator inlet tube just before the
collar of the refrigerant line connector fitting. The
probe must make contact with the bottom surface of
the evaporator inlet tube.
²If dual thermocouple probes are used, attach
probe 1 to the evaporator inlet tube, and probe 2 to
the evaporator outlet tube. Attach both probes to the
evaporator tubes just before the collar of the refrig-
erant line connector fittings. The probes must make
contact with the bottom surfaces of the evaporator
inlet and outlet tubes.
(3) Open all of the windows or doors of the passen-
ger compartment.
(4) Set the A/C button on the A/C Heater controls
to the on position, the temperature control knob in
the full cool position, select Recirculation Mode, and
place the blower motor switch in the highest speed
position.
(5) Start the engine and hold the engine idle speed
at 1,000 rpm. Allow the engine to warm up to normal
operating temperature.
(6) The compressor clutch may cycle, depending
upon ambient temperature, humidity, and the refrig-
erant system charge level.
(7) Hold the engine idle speed at 1,000 rpm.
(8) Allow three to five minutes for the refrigerant
system to stabilize, then record the temperatures of
the evaporator inlet and outlet tubes.
²If a single probe is used, record the temperature
of the evaporator inlet tube. Then remove the probe
from the inlet tube and attach it to the evaporator
outlet tube just before the collar of the refrigerant
line connector fitting. The probe must make contact
with the bottom surface of the evaporator outlet tube.
Allow the thermocouple and meter time to stabilize,
then record the temperature of the evaporator outlet
tube. Subtract the inlet tube temperature reading
from the outlet tube temperature reading.
²If dual probes are used, record the temperatures
of both the evaporator inlet and outlet tubes. Then
subtract the inlet tube temperature reading from the
outlet tube temperature reading.
(9) If the measured temperature differential is
higher than 22É C to 26É C (40É F to 47É F), add 0.4
kilograms (14 ounces) of refrigerant.
24 - 56 PLUMBINGWJ
PLUMBING (Continued)