1998 DODGE RAM 1500 rear main seal

CONDITION POSSIBLE CAUSE CORRECTION
Lubricant leaking from transfer case
seals or vent.1) Transfer case overfilled. 1) Drain lubricant to the correct
level.
2) Transfer case vent closed or
restricted.2) Clean or replace vent as
necessary.
3) Transfer case seals damaged or
installed incorrectly.3) Replace suspect seal.
Transfer case will not shift through
4HI (Part-time) range.1) Incomplete shift due to drivetrain
torque load.1) Drive in a straight line and
momentarily release the accelerator
pedal to complete the shift.
2) Incorrect tire pressure. 2) Correct tire pressure as
necessary.
3) Excessive tire wear. 3) Correct tire condition as
necessary.
4) Excessive vehicle loading. 4) Correct as necessary.
REMOVAL
(1) Shift transfer case into AWD.
(2) Raise vehicle.
(3) Drain transfer case lubricant.
(4) Mark front and rear propeller shafts for align-
ment reference.
(5) Support transmission with jack stand.
(6)
Remove the transfer case skid plate, if equipped.
(7) Disconnect front and rear propeller shafts at
transfer case.
(8) Disconnect transfer case shift motor and mode
sensor wire connectors.
(9) Disconnect transfer case vent hose.
(10) Support transfer case with transmission jack.
(11) Secure transfer case to jack with chains.
(12) Remove nuts attaching transfer case to trans-
mission (Fig. 2).(13) Pull transfer case and jack rearward to disen-
gage transfer case.
(14) Remove transfer case from under vehicle.
DISASSEMBLY
Position transfer case in a shallow drain pan.
Remove drain plug and drain any remaining lubri-
cant remaining in case.
SHIFT MOTOR ASSEMBLY AND FRONT OUTPUT
SHAFT SEAL
(1) Remove the bolts (Fig. 3) which hold the shift
motor and mode sensor assembly to the transfer
case.
Fig. 2 Remove Transfer Case - Typical
1 - TRANSMISSION
2 - TRANSFER CASE
3 - MODE SENSOR CONNECTOR
Fig. 3 Remove the Shift Motor and Mode Sensor
Assembly Bolts - Typical
1 - TRANSFER CASE
2 - SHIFT MOTOR AND MODE SENSOR ASSEMBLY
3 - BOLT
21 - 514 TRANSFER CASE - NV244 GENIIDR
TRANSFER CASE - NV244 GENII (Continued)

(4) Remove the rear output shaft retaining ring
(Fig. 16) from the output shaft.
(5) Pull front sprocket, rear sprocket, and chain
outward simultaneously (Fig. 17).
(6) Remove front sprocket, rear sprocket, and
chain as an assembly.
SHIFT FORKS AND MAINSHAFT
(1) Loosen detent plug.
(2) Remove detent plug, spring, and plunger (Fig.
18). Note that the plug has an O-ring seal. Remove
and discard this seal.
(3) Remove the front output shaft snap-ring (Fig.
19).
Fig. 18 Remove Detent Plug, Spring, and Plunger
1 - FRONT CASE
2 - DETENT PLUG
3 - DETENT SPRING
4 - DETENT PLUNGER
Fig. 19 Remove Front Output Shaft Snap-ring
1 - FRONT OUTPUT SHAFT
2 - SNAP-RING
Fig. 16 Remove Rear Output Shaft Retaining Ring
1 - REAR OUTPUT SHAFT
2 - RETAINING RING
Fig. 17 Remove Drive Sprockets and Chain
1 - FRONT DRIVE SPROCKET
2 - DRIVE CHAIN
3 - REAR DRIVE SPROCKET
21 - 518 TRANSFER CASE - NV244 GENIIDR
TRANSFER CASE - NV244 GENII (Continued)

(3) Remove front tabbed thrust washer (Fig. 36).
(4) Remove input gear (Fig. 37).
(5) Remove rear tabbed thrust washer from low
range gear (Fig. 38).
CLEANING
Clean the transfer case parts with a standard
parts cleaning solvent. Remove all traces of sealer
from the cases and retainers with a scraper and
3MŸ all purpose cleaner. Use compressed air to
remove solvent residue from oil feed passages in the
case halves, retainers, gears, and shafts.
INSPECTION
MAINSHAFT/SPROCKET/HUB INSPECTION
Inspect the splines on the hub and shaft and the
teeth on the sprocket. Minor nicks and scratches can
be smoothed with an oilstone. However, replace any
part that is damaged.
Check the contact surfaces in the sprocket bore
and on the mainshaft. Minor nicks and scratches can
be smoothed with 320-400 grit emery cloth but do not
try to salvage the shaft if nicks or wear is severe.
INPUT GEAR AND PLANETARY CARRIER
Check the teeth on the gear (Fig. 39). Minor nicks
can be dressed off with an oilstone but replace the
gear if any teeth are broken, cracked, or chipped. The
bearing surface on the gear can be smoothed with
300-400 grit emery cloth if necessary.
Examine the carrier body and pinion gears for
wear or damage. The carrier will have to be replaced
as an assembly if the body, pinion pins, or pinion
gears are damaged.
Check the lock ring and both thrust washers for
wear or cracks. Replace them if necessary. Also
replace the lock retaining ring if bent, distorted, or
broken.
SHIFT FORKS/HUBS/SLEEVES
Check condition of the shift forks and mode fork
shift rail. Minor nicks on the shift rail can be
smoothed with 320-400 grit emery cloth.
Inspect the shift fork wear pads (Fig. 40). The
mode and range fork pads are serviceable and can be
replaced if necessary.
Check both of the sleeves for wear or damage,
especially on the interior teeth. Replace the sleeves if
wear or damage is evident.
Fig. 36 Front Tabbed Thrust Washer Removal
1 - FRONT TABBED THRUST WASHER
Fig. 37 Input Gear Removal
1 - INPUT GEAR
2 - LOW RANGE GEAR
Fig. 38 Rear Tabbed Thrust Washer Removal
1 - LOW RANGE GEAR
2 - REAR TABBED THRUST WASHER
DRTRANSFER CASE - NV244 GENII 21 - 523
TRANSFER CASE - NV244 GENII (Continued)

OIL PUMP AND REAR CASE
Lubricate the oil pump components with transmis-
sion fluid before installation. Prime the oil pickup
tube by pouring a little oil into the tube before instal-
lation.
CAUTION: Do not remove the bolts holding the oil
pump cover to the rear case half. The oil pump
cover is aligned to the rear output shaft inner bear-
ing race and will become mis-aligned if the bolts
are loosened. If the transfer case failure has gener-
ated any debris which may have become trapped in
the oil pump. the rear case and oil pump assembly
MUST be replaced.
(1) Install new o-ring in pickup tube inlet of oil
pump, if necessary.
(2) Insert oil pickup tube into the oil pump.
(3) Apply bead of MopartGasket Maker, or equiv-
alent, to mating surface of front case. Keep sealer
bead width to maximum of 3/16 inch. Do not use
excessive amount of sealer as excess will be displaced
into case interior.
(4) Align oil pump with mainshaft and align shift
rail with bore in rear case. Then install rear case and
oil pump assembly (Fig. 73).
(5) Install rear output bearing snap-ring (Fig. 74)
to output shaft.
(6) Install 4-5 rear case-to front case bolts (Fig. 75)
to hold rear case in position. Tighten bolts snug but
not to specified torque at this time.
CAUTION: Verify that shift rail, and case alignment
dowels are seated before installing any bolts. Case
could be cracked if shaft rail or dowels are mis-
aligned.(7) Apply MopartLock 'n Seal Adhesive to remain-
der of rear case-to-front case bolt threads and install
bolts. Tighten bolts to 25-28 N´m (18-21 ft. lbs.),
Fig. 73 Install Rear Case
1 - REAR CASE
2 - FRONT CASE
Fig. 74 Install Output Shaft Retaining Ring
1 - REAR OUTPUT SHAFT
2 - OUTPUT SHAFT BEARING
3 - RETAINING RING
4 - TRANSFER CASE
Fig. 75 Install Case Bolts
1 - REAR CASE
2 - FRONT CASE
3 - BOLT
DRTRANSFER CASE - NV244 GENII 21 - 533
TRANSFER CASE - NV244 GENII (Continued)

TRANSFER CASE - NV273
TABLE OF CONTENTS
page page
TRANSFER CASE - NV273
DESCRIPTION........................542
OPERATION..........................543
DIAGNOSIS AND TESTING - TRANSFER
CASE - NV273.......................543
REMOVAL............................544
DISASSEMBLY........................544
CLEANING...........................554
INSPECTION.........................554
ASSEMBLY...........................556
INSTALLATION........................568
SPECIFICATIONS
TRANSFER CASE - NV273.............568
SPECIAL TOOLS
TRANSFER CASE NV271/NV273.........569
EXTENSION HOUSING SEAL AND DUST BOOT
REMOVAL............................571
INSTALLATION........................571FLUID
STANDARD PROCEDURE - FLUID DRAIN AND
REFILL............................571
FRONT OUTPUT SHAFT SEAL
REMOVAL............................572
INSTALLATION........................572
MODE SENSOR
DESCRIPTION........................573
OPERATION..........................573
SELECTOR SWITCH
DESCRIPTION........................574
OPERATION..........................574
SHIFT MOTOR
DESCRIPTION........................575
OPERATION..........................575
REMOVAL............................575
INSTALLATION........................575
TRANSFER CASE - NV273
DESCRIPTION
The NV273 is an electronically controlled part-time
transfer case with a low range gear reduction system.
The NV273 has three operating ranges plus a NEU-
TRAL position. The low range system provides a gear
reduction ratio for increased low speed torque capa-
bility.
The geartrain is mounted in two aluminum case
halves attached with bolts. The mainshaft front and
rear bearings are mounted in aluminum case halves.
OPERATING RANGES
Transfer case operating ranges are:
²2WD (2-wheel drive)
²4HI (4-wheel drive)
²4LO (4-wheel drive low range)
²NEUTRAL
The 2WD range is for use on any road surface at
any time.The 4HI and 4LO ranges are for off road use only.
They are not for use on hard surface roads. The only
exception being when the road surface is wet or slip-
pery or covered by ice and snow.
The low range reduction gear system is operative
in 4LO range only. This range is for extra pulling
power in off road situations. Low range reduction
ratio is 2.72:1.
SHIFT MECHANISM
Operating ranges are selected with a dash
mounted shift selector switch. The shift selector
switch provides a input to the Transfer Case Control
Module (TCCM) to indicate the driver's desire to
change operating ranges. The TCCM uses this input,
along with input from the transfer case mounted
mode sensor and information from the vehicle's bus,
to determine if a shift is permitted. If the TCCM
decides the shift is permitted, the TCCM controls the
shift motor, mounted to the exterior of the transfer
case, to perform the shift.
21 - 542 TRANSFER CASE - NV273DR

Condition Possible Cause Correction
Transfer case noisy while in, or
jumps out of, 4LO mode.1) Transfer case not completely
engaged in 4LO position.1) While rolling 2-3 MPH and the
transmission in NEUTRAL, or clutch
depressed on vehicles equipped
with a manual transmission, shift
transfer case to the 2WD or 4HI
position, and then back into the 4LO
position.
2) Range fork damaged, inserts
worn, or fork is binding on the shift
rail.2) Repair or replace components as
necessary.
3) Low range gear worn or
damaged.3) Repair or replace components as
necessary.
Lubricant leaking from transfer case
seals or vent.1) Transfer case overfilled. 1) Drain lubricant to the correct
level.
2) Transfer case vent closed or
restricted.2) Clean or replace vent as
necessary.
3) Transfer case seals damaged or
installed incorrectly.3) Replace suspect seal.
Abnormal tire wear. 1) Extended operation in 4HI mode
on dry surfaces,1) Operate vehicle in 2WD mode on
dry surfaces.
REMOVAL
(1) Shift transfer case into 2WD.
(2) Raise vehicle.
(3) Drain transfer case lubricant.
(4) Mark front and rear propeller shafts for align-
ment reference.
(5) Support transmission with jack stand.
(6) Remove the transfer case skid plate, if
equipped.
(7) Disconnect front and rear propeller shafts at
transfer case.
(8) Disconnect transfer case shift motor and mode
sensor wire connectors.
(9) Disconnect transfer case vent hose.
(10) Support transfer case with transmission jack.
(11) Secure transfer case to jack with chains.
(12) Remove nuts attaching transfer case to trans-
mission (Fig. 2).
(13) Pull transfer case and jack rearward to disen-
gage transfer case.
(14) Remove transfer case from under vehicle.
DISASSEMBLY
Position transfer case in a shallow drain pan.
Remove drain plug and drain any remaining lubri-
cant remaining in case.
Fig. 2 Remove Transfer Case - Typical
1 - TRANSMISSION
2 - TRANSFER CASE
3 - MODE SENSOR CONNECTOR
21 - 544 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)

(6) Using a screw mounted in a slide hammer,
remove the front output shaft seal.
(7) Remove the front output shaft snap-ring (Fig.
22).
(8) Remove front output shaft from bearing in case
(Fig. 23).(9) Pull mainshaft assembly out of input gear,
mode sleeve, and case (Fig. 24).
(10) Remove mode fork, mode sleeve, and shift rail
as assembly (Fig. 25). Note which way the sleeve fits
in the fork (long side of sleeve goes to front or the
points on the sleeve teeth go to the rear of case).
Fig. 22 Remove Front Output Shaft Bearing Inner
Snap-Ring
1 - FRONT CASE HALF
2 - SNAP-RING
Fig. 23 Remove Front Output Shaft
1 - FRONT CASE
2 - FRONT OUTPUT SHAFT
Fig. 24 Remove Mainshaft Assembly
1 - FRONT CASE HALF
2 - MAINSHAFT ASSEMBLY
Fig. 25 Mode Fork And Sleeve Removal
1 - MODE SLEEVE
2 - MODE FORK AND RAIL
21 - 550 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)

(8) Remove bottom tabbed thrust washer from low
range planetary (Fig. 38).
CLEANING
Clean the transfer case parts with a standard
parts cleaning solvent. Remove all traces of sealer
from the cases and retainers with a scraper and
3MŸ all purpose cleaner. Use compressed air to
remove solvent residue from oil feed passages in the
case halves, retainers, gears, and shafts.
INSPECTION
MAINSHAFT/SPROCKET/HUB INSPECTION
Inspect the splines on the hub and shaft and the
teeth on the sprocket. Minor nicks and scratches can
be smoothed with an oilstone. However, replace any
part that is damaged.
Check the contact surfaces in the sprocket bore
and on the mainshaft. Minor nicks and scratches can
be smoothed with 320-400 grit emery cloth but do not
try to salvage the shaft if nicks or wear is severe.
INPUT GEAR AND PLANETARY CARRIER
Check the teeth on the gear (Fig. 39). Minor nicks
can be dressed off with an oilstone but replace the
gear if any teeth are broken, cracked, or chipped. The
bearing surface on the gear can be smoothed with
300-400 grit emery cloth if necessary.
Examine the carrier body and pinion gears for
wear or damage. Check the pinion gear thrust wash-
ers on the pinon pins for damage. The carrier will
have to be replaced as an assembly if the body, pin-
ion pins, or pinion gears are damaged.
Check the lock ring and both thrust washers for
wear or cracks. Replace them if necessary. Also
replace the lock retaining ring if bent, distorted, or
broken.
Fig. 39 Input Gear And Carrier Components
1 - PLANETARY CARRIER 4 - CARRIER LOCK RING
2 - REAR THRUST WASHER 5 - CARRIER LOCK RETAINING RING
3 - FRONT THRUST WASHER 6 - INPUT GEAR
Fig. 38 Remove Bottom Input Gear Thrust Plate
1 - PLANETARY
2 - THRUST PLATE
21 - 554 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)