(3) Install new oil seal in housing using Seal
Installer C-3995-A (Fig. 84).
EXTENSION HOUSING SEAL
REMOVAL
(1) Raise vehicle.
(2) Mark propeller shaft and axle yoke for align-
ment reference.
(3) Disconnect and remove propeller shaft.
(4) Remove old seal with Seal Remover C-3985-B
(Fig. 85) from overdrive housing.
INSTALLATION
(1) Place seal in position on overdrive housing.
(2) Drive seal into overdrive housing with Seal
Installer C-3995-A (Fig. 86).
(3) Carefully guide propeller shaft slip yoke into
housing and onto output shaft splines. Align marks
made at removal and connect propeller shaft to rear
axle pinion yoke.
FLUID AND FILTER
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - EFFECTS OF
INCORRECT FLUID LEVEL
A low fluid level allows the pump to take in air
along with the fluid. Air in the fluid will cause fluid
pressures to be low and develop slower than normal.
If the transmission is overfilled, the gears churn the
fluid into foam. This aerates the fluid and causing
the same conditions occurring with a low level. In
either case, air bubbles cause fluid overheating, oxi-
dation and varnish buildup which interferes with
valve and clutch operation. Foaming also causes fluid
expansion which can result in fluid overflow from the
transmission vent or fill tube. Fluid overflow can eas-
ily be mistaken for a leak if inspection is not careful.
DIAGNOSIS AND TESTING - CAUSES OF
BURNT FLUID
Burnt, discolored fluid is a result of overheating
which has two primary causes.
Fig. 83 Bushing Removal - Typical
1 - REMOVER 6957
2 - EXTENSION HOUSING BUSHING
Fig. 84 Extension Housing Seal Installation
1 - SPECIAL TOOL C-3995-A OR C-3972-A
2 - SPECIAL TOOL C-4471
Fig. 85 Removing Overdrive Housing Yoke Seal
1 - SPECIAL TOOL C-3985-B
2 - SEAL
Fig. 86 Installing Overdrive Housing Seal
1 - SPECIAL TOOL C-3995-A OR C-3972-A
2 - SPECIAL TOOL C-4471
WJAUTOMATIC TRANSMISSION - 42RE 21 - 69
EXTENSION HOUSING BUSHING (Continued)
INPUT AND LOW RANGE GEARS
Inspect the low range gear pinions and pinion pins.
Replace the low range gear if any of the pins or pin-
ions are worn or damaged.
Inspect the thrust washers, retainer, and snap-
ring. Replace the snap-ring if bent, or distorted.
Replace the thrust washers and retainer if worn,
cracked or damaged in any way.
Examine the input gear carefully. Be sure the gear
teeth and bearing surfaces are in good condition.
Replace the gear if wear or damage is evident.
Check the input gear pilot bearing. Rotate the
bearing and check for roughness or noise. Also check
bearing position in the bore. The bearing should be
recessed approximately 2.5 mm (0.100 in.) below the
top edge of the bore. The bearing should not be
seated at the bottom of the bore. Replace the bearing
if worn, or roughness is evident. Replace both the
gear and bearing if the bearing is a loose fit in the
bore.
GEAR CASE AND RETAINERS
Examine both case halves and retainers carefully.
Replace any retainer or case half if wear, cracks, or
other damage is evident.
Check condition of the low range annulus gear and
the shift rail bushing in the front case (Fig. 32). The
low range annulus gear is not a serviceable part.
Replace the gear and case as an assembly if the gear
is loose, worn, or damaged. The shift rail bushing is
a serviceable part and can be replaced if necessary.
Check the bushing in the rear retainer. Replace the
bushing if worn or scored.
Examine the sealing surfaces of both case halves
and retainers. Small burrs, or scratches on these sur-
faces can be reduced with crocus cloth or a fine tooth
file.
Examine condition of the shift rail bushing in the
front case. If the bushing is worn or damaged, it can
be removed with a blind hole type puller. A replace-
ment bushing can be installed with a suitable size
driver. Recess the bushing slightly below the edge of
the bore but do not seat it all the into the case.
GEARTRAIN
Inspect the mainshaft splines, gear teeth and bear-
ing surfaces carefully for evidence of wear, or dam-
age. Replace the shaft if necessary. do not attempt to
salvage it if damaged.
The shift rail and range fork are an assembly.
Replace both parts if either is damaged. However, the
nylon pads in the fork can be replaced if worn, or
cracked.
Inspect the transfer case snap-rings closely. Do not
attempt to salvage a distorted snap-ring by straight-ening or reshaping it. Replace any snap-ring that is
distorted, or worn.
Inspect the low range gear, input gear and the gear
thrust washers retainer, and snap-ring. The low
range gear is serviced as an assembly only. Replace
the gear if the case or pinions are damaged.
During inspection, also make sure the seal surface
of the input gear is in good condition. Minor nicks on
this surface can be reduced with crocus cloth. How-
ever, replace the gear if the seal surface is severely
scored or worn.
OIL PUMP AND PROGRESSIVE COUPLING
The oil pump and progressive coupling are not ser-
viceable components. Replace the coupling as an
assembly if it is damaged. Replace the oil pump as
an assembly if the gear teeth are worn, or if the
pump has become damaged.
BEARINGS AND SEALS
The transfer case seals should be replaced during
overhaul. Use new seals in the input gear bearing
retainer, front case and rear retainer. Also replace
the yoke seal washer and the detent plug O-ring.
Check condition of each transfer case bearing.
Replace any bearing exhibiting signs of roughness,
wear, or damage.
Fig. 32 Low Range Annulus Gear Location
1 - LOW RANGE ANNULUS GEAR
2 - SHIFT RAIL BUSHING
WJTRANSFER CASE - NV247 21 - 325
TRANSFER CASE - NV247 (Continued)
