Page 1860 of 2627

CONDITION POSSIBLE CAUSES CORRECTION
OIL LEAKS. 1. Fluid Lines and Fittings Loose/
Leaks/Damaged.1. Tighten fittings. If leaks persist, replace
fittings and lines if necessary.
2. Fill Tube (where tube enters case)
Leaks/Damaged.2. Replace tube seal. Inspect tube for
cracks in fill tube.
3. Pressure Port Plug Loose
Loose/Damaged.3. Tighten to correct torque. Replace plug
or reseal if leak persists.
4. Pan Gasket Leaks. 4. Tighten pan screws (150 in. lbs.). If leaks
persist, replace gasket.
5. Valve Body Manual Lever Shaft
Seal Leaks/Worn.5. Replace shaft seal.
6. Rear Bearing Access Plate Leaks. 6. Replace gasket. Tighten screws.
7. Gasket Damaged or Bolts are
Loose.7. Replace bolts or gasket or tighten both.
8. Adapter/Extension Gasket
Damaged Leaks/Damaged.8. Replace gasket.
9. Park/Neutral Switch, or
Transmission Range Sensor
Leaks/Damaged.9. Replace switch and gasket.
10. Converter Housing Area Leaks. 10. Check for leaks at seal caused by worn
seal or burr on converter hub (cutting seal),
worn bushing, missing oil return, oil in front
pump housing or hole plugged. Check for
leaks past O-ring seal on pump or past
pump-to-case bolts; pump housing porous,
oil coming out vent due to overfill or leak
past front band shaft access plug.
11. Pump Seal Leaks/Worn/
Damaged.11. Replace seal.
12. Torque Converter Weld
Leak/Cracked Hub.12. Replace converter.
13. Case Porosity Leaks. 13. Replace case.
NOISY OPERATION IN
FOURTH GEAR ONLY1. Overdrive Clutch Discs, Plates or
Snap Rings Damaged.1. Remove unit and rebuild clutch pack.
2. Overdrive Piston or Planetary
Thrust Bearing Damaged.2. Remove and disassemble unit. Replace
either thrust bearing if damaged.
3. Output Shaft Bearings Scored/
Damaged.3. Remove and disassemble unit. Replace
either bearing if damaged.
4. Planetary Gears Worn/Chipped. 4. Remove and overhaul overdrive unit.
5. Overdrive Unit Overrunning Clutch
Rollers Worn/Scored.5. Remove and overhaul overdrive unit.
DRAUTOMATIC TRANSMISSION - 48RE 21 - 157
AUTOMATIC TRANSMISSION - 48RE (Continued)
Page 1861 of 2627

STANDARD PROCEDURE - ALUMINUM
THREAD REPAIR
Damaged or worn threads in the aluminum trans-
mission case and valve body can be repaired by the
use of Heli-CoilsŸ, or equivalent. This repair con-
sists of drilling out the worn-out damaged threads.
Then tap the hole with a special Heli-CoilŸ tap, or
equivalent, and installing a Heli-CoilŸ insert, or
equivalent, into the hole. This brings the hole back to
its original thread size.
Heli-CoilŸ, or equivalent, tools and inserts are
readily available from most automotive parts suppli-
ers.
REMOVAL
NOTE: The overdrive unit can be removed and ser-
viced separately. It is not necessary to remove the
entire transmission assembly to perform overdrive
unit repairs.
(1) Disconnect battery negative cable.
(2) Raise vehicle.
(3) Remove the transfer case skid plate (Fig. 12), if
equipped.(4) Disconnect and lower or remove necessary
exhaust components.
(5) Remove engine-to-transmission struts.
(6) Remove starter motor. (Refer to 8 - ELECTRI-
CAL/STARTING/STARTER MOTOR - REMOVAL)
(7) Disconnect and remove the crankshaft position
sensor. (Refer to 14 - FUEL SYSTEM/FUEL INJEC-
TION/CRANKSHAFT POSITION SENSOR -
REMOVAL) Retain the sensor attaching bolts.
(8) If transmission is being removed for overhaul,
remove transmission oil pan, drain fluid and reinstall
pan.
(9) Remove torque converter access cover.
(10) Rotate crankshaft in clockwise direction until
converter bolts are accessible. Then remove bolts one
at a time. Rotate crankshaft with socket wrench on
dampener bolt.
(11) Mark propeller shaft and axle yokes for
assembly alignment. Then disconnect and remove
propeller shaft. On4x4models, remove both propel-
ler shafts. (Refer to 3 - DIFFERENTIAL & DRIV-
ELINE/PROPELLER SHAFT/PROPELLER SHAFT -
REMOVAL)
(12) Disconnect wires from the transmission range
sensor and transmission solenoid connector.
(13) Disconnect gearshift cable (Fig. 13) from the
transmission.
Fig. 12 Transfer Case Skid Plate
1 - FRAME RAIL
2 - SKID PLATE
3 - BOLTS (6)
Fig. 13 Gearshift Cable At Transmission
1 - GEARSHIFT CABLE
2 - TRANSMISSION MANUAL LEVER
3 - CABLE SUPPORT BRACKET
21 - 158 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)
Page 1862 of 2627

(14) Disconnect throttle valve cable from transmis-
sion bracket and throttle valve lever.
(15) On 4X4 models, disconnect shift rod from
transfer case shift lever.
(16) Support rear of engine with safety stand or
jack.
(17) Raise transmission slightly with service jack
to relieve load on crossmember and supports.
(18) Remove bolts securing rear support and cush-
ion (Fig. 14) and (Fig. 15) to transmission and cross-
member and remove rear support.
(19) Remove bolts attaching crossmember to frame
and remove crossmember.
(20) On 4X4 models, remove transfer case with
transmission jack or aid of helper.
(21) Disconnect fluid cooler lines at transmission.
(22) Remove fill tube bracket bolts and pull tube
out of transmission. Retain fill tube seal. On 4X4
models, it will also be necessary to remove bolt
attaching transfer case vent tube to converter hous-
ing (Fig. 16).
(23) Remove all converter housing bolts.
(24) Carefully work transmission and torque con-
verter assembly rearward off engine block dowels.
(25) Lower transmission and remove assembly
from under the vehicle.
(26) To remove torque converter, remove C-clamp
from edge of bell housing and carefully slide torque
converter out of the transmission.
Fig. 14 Engine Rear Mount - 4X2 Automatic
Transmission
1 - ENGINE REAR MOUNT
2 - BOLT
3 - NUT
4 - THROUGH BOLT NUT
5 - TRANSMISSION
Fig. 15 Engine Rear Mount - 4X4 Automatic
Transmission
1 - TRANSMISSION
2 - ENGINE REAR MOUNT
3 - BOLT
Fig. 16 Fill Tube Attachment
1 - TRANSFER CASE VENT TUBE
2 - FILL TUBE (V8)
3 - TUBE SEAL
4 - FILL TUBE (V6)
DRAUTOMATIC TRANSMISSION - 48RE 21 - 159
AUTOMATIC TRANSMISSION - 48RE (Continued)
Page 1863 of 2627

DISASSEMBLY
(1) Clean exterior of transmission with suitable
solvent or pressure washer.
(2) Place transmission in vertical position.
(3) Measure the input shaft end play as follows
(Fig. 17).
(a) Attach Adapter 8266-5 to Handle 8266-8.
(b) Attach dial indicator C-3339 to Handle
8266-8.
(c) Install the assembled tool onto the input
shaft of the transmission and tighten the retaining
screw on Adapter 8266-5 to secure it to the input
shaft.
(d) Position the dial indicator plunger against a
flat spot on the oil pump and zero the dial indica-
tor.
(e) Move input shaft in and out and record read-
ing. Record the maximum travel for assembly ref-
erence
(4) Remove the overdrive unit from the main
transmission case. If overdrive unit is not to be ser-
viced, install Alignment Shaft 6227-2 into the over-
drive unit to prevent misalignment of the overdrive
clutches during service of main transmission compo-
nents.
(5) Remove throttle and shift levers from valve
body manual shaft and throttle lever shaft.
(6) Remove transmission oil pan and gasket.(7) Remove filter from valve body (Fig. 18). Keep
filter screws separate from other valve body screws.
Filter screws are longer and should be kept with fil-
ter.
(8) Remove the transmission range sensor.
(9) Remove hex head bolts attaching valve body to
transmission case (Fig. 19). A total of 10 bolts are
used. Note different bolt lengths for assembly refer-
ence.
Fig. 19 Valve Body Bolt Locations
1 - VALVE BODY BOLTS
2 - VALVE BODY BOLTS
Fig. 17 Checking Input Shaft End Play
1 - TOOL 8266-8
2 - TOOL 8266-5
3 - TOOL C-3339
Fig. 18 Oil Filter Removal
1 - OIL FILTER
2 - VALVE BODY
3 - FILTER SCREWS (2)
21 - 160 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)
Page 1864 of 2627

(10) Remove valve body assembly. Push valve body
harness connector out of case. Then work park rod
and valve body out of case (Fig. 20).
(11) Remove accumulator outer spring, piston and
inner spring (Fig. 21). Note position of piston and
springs for assembly reference. Remove and discard
piston seals if worn or cut.
(12) Remove pump oil seal with suitable pry tool
or slide-hammer mounted screw.
(13) Remove front band lever pin access plug (Fig.
22). Use square end of 1/4 in. drive extension to
remove plug as shown.(14) Remove oil pump and reaction shaft support
assembly as follows:
(a) Tighten front band adjusting screw until
band is tight around front clutch retainer (Fig. 23).
This will prevent retainer from coming out with
pump and possibly damaging clutch or pump com-
ponents.
Fig. 23 Tightening Front Band To Hold Front Clutch
In Place
1 - LOCK-NUT
2 - FRONT BAND ADJUSTER
Fig. 20 Valve Body Removal
1 - GOVERNOR PRESSURE SENSOR
2 - VALVE BODY
3 - PARK ROD
4 - ACCUMULATOR PISTON
5 - GOVERNOR PRESSURE SOLENOID
Fig. 21 Accumulator Component Removal
1 - ACCUMULATOR PISTON
2 - OUTER SPRING
3 - INNER SPRING
Fig. 22 Front Band Lever Pin Access Plug
1 - FRONT BAND REACTION PIN ACCESS PLUG
2 - 1/4 DRIVE EXTENSION AND RATCHET
DRAUTOMATIC TRANSMISSION - 48RE 21 - 161
AUTOMATIC TRANSMISSION - 48RE (Continued)
Page 1865 of 2627
(b) Remove oil pump bolts.
(c) Thread Slide Hammer Tools C-3752 into
threaded holes in flange of oil pump housing (Fig.
24).
(d) Remove oil pump and reaction shaft support
by bumping slide hammers outward alternately to
pull pump from case (Fig. 25).
(15) Remove oil pump gasket (Fig. 26). Note gas-
ket position in case for assembly reference.(16) Loosen front band adjusting screw until band
is completely loose.
(17) Remove front band strut and anchor (Fig. 27).
Fig. 24 Oil Pump Removal Tools
1 - PUMP HOUSING
2 - SLIDE HAMMER TOOLS (THREAD INTO PUMP HOUSING)
Fig. 25 Oil Pump Removal
1 - OIL PUMP AND REACTION SHAFT SUPPORT
Fig. 26 Oil Pump Gasket
1 - OIL PUMP GASKET
Fig. 27 Front Band Linkage
1 - LEVER
2 - STRUT
3 - ANCHOR
4 - FRONT BAND
21 - 162 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)
Page 1866 of 2627
(18) Squeeze front band together slightly and slide
band over front clutch retainer and out of case (Fig.
28).
(19) Remove front and rear clutch assemblies as a
unit (Fig. 29).(20) Remove front band reaction pin and lever.
Start pin through lever and out of case bore with
drift or punch. Then use pencil magnet to withdraw
pin completely (Fig. 30).
(21) Remove intermediate shaft thrust washer. Tri-
angular shaped washer will either be on shaft pilot
hub or in rear clutch retainer (Fig. 31).
Fig. 29 Removing Front/Rear Clutch Assemblies
1 - FRONT AND REAR CLUTCH ASSEMBLIES
Fig. 30 Front Band Lever And Pin
1 - BAND LEVER
2 - USE PENCIL MAGNET TO REMOVE REACTION PIN
Fig. 31 Intermediate Shaft Thrust Washer
1 - THRUST WASHER
2 - INTERMEDIATE SHAFT PILOT HUB
Fig. 28 Front Band Removal
1 - FRONT BAND
2 - FRONT CLUTCH RETAINER
DRAUTOMATIC TRANSMISSION - 48RE 21 - 163
AUTOMATIC TRANSMISSION - 48RE (Continued)
Page 1867 of 2627
(22) Remove thrust plate from intermediate shaft
hub (Fig. 32).
(23) Remove intermediate shaft-planetary
geartrain assembly (Fig. 33).
(24) Loosen rear band locknut and loosen adjust-
ing screw 3-4 turns.
(25) Remove snap-ring that retains low-reverse
drum on overdrive piston retainer hub (Fig. 34).
(26) Slide low-reverse drum and thrust washer off
piston retainer hub and out of rear band (Fig. 35).
Fig. 35 Low-Reverse Drum And Thrust Washer
1 - LOW-REVERSE DRUM
2 - SPOTFACE FOR WASHER
3 - THRUST WASHER
Fig. 32 Intermediate Shaft Thrust Plate
1 - SHAFT THRUST PLATE
2 - INTERMEDIATE SHAFT PILOT HUB
Fig. 33 Intermediate Shaft And Planetary Geartrain
1 - INTERMEDIATE SHAFT AND PLANETARY GEAR TRAIN
ASSEMBLY
Fig. 34 Low-Reverse Drum Snap-Ring
1 - LOW-REVERSE DRUM
2 - TABBED WASHER
3 - SNAP-RING
21 - 164 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)