1991 MITSUBISHI MONTERO check oil

POWER BRAKE UNIT CHECK VALVE
NOTE: To test check valve before removal, stop engine, and apply
service brake to ensure air flows only toward intake
manifold.
Removal & Installation
Loosen hose clamps, and remove check valve. Before
installation, coat both ends of check valve with sealant, and install
valve with arrow (identification mark) pointing toward intake
manifold. Install check valve clamp, and secure hose clamps.
POWER BRAKE UNIT
Removal
Remove brake master cylinder. Disconnect vacuum hose from
power brake unit. Disconnect clevis pin attaching brake pedal to power
brake unit push rod. From inside vehicle, remove 4 nuts attaching
power brake unit to firewall. Remove power brake unit.
Installation
To install, reverse removal procedure. Install master
cylinder. Bleed brake system if necessary.
REAR AXLE BEARINGS & OIL SEAL
Removal (Montero)
1) With drum removed, disconnect brake line from wheel
cylinder. Disconnect bearing case from axle housing end. Remove brake
backing plate, bearing case and axle shaft as an assembly. If axle
shaft binds, use slide hammer with puller to remove.
2) Remove "O" ring and shims for preloading wheel bearing (if\
equipped). Retain shims for reassembly. To remove oil seal, use slide
hammer and hook.
3) To remove wheel bearing, straighten lock washer tabs. See
Fig. 9 . Remove lock nut using spanner wrench. Remove lock washer.
Install lock nut 3 turns on axle shaft. Install Puller (MB990787-01)
to remove axle shaft from bearing case. Rotate nuts with equal force
to remove axle shaft. Remove bearing outer race using a hammer and
drift.
Fig. 9: Removing Rear Axle Bearing (Montero)
Courtesy of Mitsubishi Motor Sales of America.
Installation
1) Apply Multipurpose Grease (SAE J310) to oil seal. Install\

oil seal using seal driver. Apply grease to outside circumference of
bearing outer race. Apply grease to lip of oil seal and to roller
surfaces of bearing inner race.
2) Press bearing onto axle shaft. Install rear brake assembly
and bearing case. Pack bearing case and axle threads with grease.
Install lock washer (tab aligned with axle slot) and lock nut (chamfe\
r
toward lock washer). Tighten lock nut to 130-159 ft. lbs. (176-216 N.
m).
3) Bend tabs on lock washer into slots of lock nut. Apply
grease to oil seal area of rear axle housing. Adjust clearance between
bearing case and rear axle by inserting .04" (1.0 mm) shim and "O"
ring into left rear axle housing.
4) Apply semi-drying sealant to mating surface of bearing
case. Install left axle shaft into rear housing. Tighten nuts
diagonally to 36-43 ft. lbs. (49-58 N.m).
5) Install right axle shaft without shims and "O" ring.
Temporarily tighten to about 53 INCH lbs. (6 N.m). Using a feeler
gauge, measure clearance between bearing case and rear axle housing.
6) Remove right axle shaft. Install shims to equal bearing
case-to-axle housing clearance plus .002-.008" (.05-.20 mm). Install
"O" ring to right rear axle housing. Apply sealant to mating surfaces
of bearing case and shim. See Fig. 10.
7) Install axle into housing, tightening nuts diagonally to
36-43 ft. lbs. (50-58 N.m). Check axle shaft for .002-.008" (.05-.20
mm) end play using dial indicator.
Fig. 10: Applying Sealant (Montero, Pickup & Ram-50)
Courtesy of Mitsubishi Motor Sales of America.
Removal (Pickup & Ram-50)
1) With drum removed, disconnect brake line from wheel

Remove bearing outer race using a hammer and drift. Remove oil seal
from axle housing using a slide hammer and hook.
Installation
1) Apply Multipurpose Grease (SAE J310) to oil seal. Install\
oil seal using seal driver. Apply grease to outside circumference of
oil seal lip. Install backing plate and bearing case. Apply grease to
oil seal.
2) Press new oil seal into bearing case until it is flush
with face of bearing case. Apply grease to lip of oil seal and to
external surfaces of bearing outer race. Press bearing outer race into
bearing case.
3) Apply grease to roller surfaces of bearing inner race.
Install rear brake assembly and bearing case. Pack bearing case and
axle threads with grease. Install new retainer ring.
4) Adjust clearance between bearing case and rear axle by
inserting .04" (1.0 mm) shim and "O" ring into left rear axle housing.\
Apply semi-drying sealant to mating surface of bearing case. Install
left axle shaft into rear housing. Tighten nuts diagonally to 36-43
ft. lbs. (50-58 N.m).
5) Install right axle shaft without shims and "O" ring.
Temporarily tighten to about 53 INCH lbs. (6 N.m). Using a feeler
gauge, measure clearance between bearing case and rear axle housing.
6) Remove right axle shaft. Install shims to equal bearing
case-to-axle housing clearance plus .002-.008" (.05-.20 mm). Install
"O" ring to right rear axle housing. Apply sealant to mating surface
of bearing case. See Fig. 10.
7) Install axle into housing, tightening nuts diagonally to
36-43 ft. lbs. (49-58 N.m). Check axle shaft for .002-.008" (.05-.20
mm) end play using dial indicator.
OVERHAUL
NOTE: For exploded views of front disc brake caliper, see Fig. 12.
For exploded view of master cylinder, see Fig. 13.
Fig. 12: Exploded View of Front Disc Brake Caliper (Typical)
Courtesy of Mitsubishi Motor Sales of America.

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DRIV E A XLE - F R O NT

1991 M it s u bis h i M onte ro
1990-92 DRIVE AXLES
Differentials & Axle Shafts - Front
Montero, Pickup 4WD
DESCRIPTION
Front axle assembly consists of differential carrier, housing
tube, inner shaft and drive axles. A full-floating axle design is
used. Drive axles are flexible assemblies made up of inner and outer
CV joints. Birfield Joints (BJ) and Double Offset Joints (DOJ) are
used at opposite ends of each drive axle.
AXLE RATIO & IDENTIFICATION
Ratio is determined by dividing number of ring gear teeth by
number of drive pinion teeth.
AXLE RATIO SPECIFICATIONS









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Application Ratio
Montero ............................ 4.63:1
Pickup ............................. 4.22:1









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NOTE: References to BJ refer to Birfield Joint and DOJ to Double
Offset Joint.
TESTING
TOTAL ASSEMBLY BACKLASH
Place transfer case in "4H" position. Raise and support
vehicle. Check total backlash at flange. If backlash at flange exceeds
.55" (14.0 mm), check assembly for wear and proper adjustment.
DRIVE AXLES R & I
REMOVAL
1) Remove undercover on Montero. Place hub in free-wheeling
position. Place transfer case in 2H position. Remove drive hub cover,
snap ring and shim from drive axle. Remove brake calipers and wire out
of way.
2) Using dial indicator, check drive axle end play. Rotate
drive axle forward and rearward until maximum end play is obtained.
End play must be adjusted during reassembly if not within .008-.020"
(.20-.50 mm). Disconnect tie rod assembly. Support lower control arm
with jack.
3) Separate ball joints from knuckle. Remove knuckle and
front hub assembly. Remove left drive axle from differential carrier.
Use care not to damage oil seal. On right drive axle, remove drive
axle-to-inner shaft retaining bolts. Remove right drive axle.
CAUTION: Support lower control arm during drive axle removal and
installation.

CAUTION: Always replace circlips on BJ splines of left drive axle
and splines of inner shaft.
INSTALLATION
1) Install right drive axle on inner shaft. Install new
circlip on BJ side of left drive axle. Drive left drive axle into
differential. Use care not to damage oil seal.
2) Reinstall knuckle with front hub assembly. If drive axle
end play requires adjustment, select proper shim to obtain proper end
play. Shim is located behind snap ring on end of drive axle. Install
shim and recheck axle end play. Install remaining components in
reverse of removal procedure.
DIFFERENTIAL CARRIER R & I
REMOVAL
1) Raise and support vehicle. Drain gear oil. Support
differential carrier. Remove drive axles and inner shaft. See DRIVE
AXLES R & I and INNER SHAFT & BEARING R & I in this article. Place
alignment mark on drive shaft and pinion flange for reassembly
reference.
2) Remove drive shaft. Remove differential mounting brackets
at differential and frame. See Fig. 1. Disconnect front crossmember
from frame. Remove differential carrier assembly and front
crossmember. Remove differential carrier from front crossmember.
INSTALLATION
To install, reverse removal procedure. Align marks on drive
shaft and pinion flange.

must be installed in original location.
2) Using bearing puller, remove differential case side
bearings. Loosen ring gear retaining bolts in diagonal sequence.
Remove ring gear.
3) Remove drive pinion shaft lock pin from ring gear side.
Remove pinion shaft and pinion gears. Remove side gears and thrust
spacers.
DRIVE PINION
1) Remove pinion flange nut. Scribe alignment mark on pinion
flange and pinion. Remove flange. Using soft-faced hammer, drive out
pinion. Remove rear bearing and oil seal from carrier. Remove rear
adjusting shim from pinion.
2) Press front bearing from pinion. Remove front adjusting
shim and spacer from pinion. Inspect all components for unusual wear
or damage. Replace as necessary.
DIFFERENTIAL REASSEMBLY & ADJUSTMENTS
CASE REASSEMBLY
1) Place side gear thrust spacers behind side gears in
original position. Assemble side gears in differential case. Install
pinion gears and washers. Rotate pinion gears to mesh with side gears.
2) Install pinion shaft without lock pin. Check pinion and
side gear backlash. Install wooden wedge to lock side gears. Using
dial indicator, measure gear backlash. See Fig. 3.
3) Backlash must be within specification. See PINION & SIDE
GEAR BACKLASH SPECIFICATIONS table. Adjust backlash by using different
side gear spacers. Ensure both sides are equally shimmed.
4) Install pinion shaft lock pin. Securely stake in 2 places.
Ensure adhesive is removed from ring gear mounting bolts and gear
mounting surface. Clean internal threads with tap.
5) Install ring gear on differential case. Ensure alignment
marks on differential case and ring gear are aligned. Apply Loctite
271 to bolts and install. Tighten bolts alternately in diagonal
sequence to specification. See TORQUE SPECIFICATIONS table at the end
of this article.
PINION & SIDE GEAR BACKLASH SPECIFICATIONS









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Application In. (mm)
Standard ....................... .003 (.08)
Wear Limit ..................... .008 (.20)









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1) Install drive pinion in differential carrier. Install
spacer, pinion front shim(s) and front pinion bearing. DO NOT install
oil seal at this time. Install pinion flange, washer and retaining
nut. Check pinion rotating torque without pinion oil seal.
2) Recheck rotating torque. Rotating torque must be within
specification. See PINION ROTATING TORQUE SPECIFICATIONS table. Adjust
rotating torque by replacing drive pinion front shims or spacer. Once
correct rotating torque is obtained, install oil seal. Coat seal lip
with grease.
3) Install pinion flange so alignment marks are correct.
Apply light coat of grease to flange washer contact area. Install new
retaining nut. Check pinion rotating torque with pinion oil seal
installed. Rotating torque must be within specification. See PINION
ROTATING TORQUE SPECIFICATIONS table.
SIDE BEARING
1) Using Bearing Installer (MB990802-01), install bearings o\
n
differential case. Select 2 side bearing adjusting shims thinner than
those removed. Shims must be equal thickness on both sides. Install
shims on each side of case assembly. Install case assembly in
differential carrier.
2) Push case assembly fully to one side of carrier. Using 2
feeler gauges, measure clearance between carrier and side bearing shim
at opposite sides of bearing. Remove shims from one side of
differential carrier.
3) Measure thickness of shims removed. Add removed shim
thickness and 1/2 of feeler gauge clearance measurement plus .002" (.
05 mm). This is thickness of shim that should be installed on each
side of case. Select proper shims. Install equal shims on each side of
case assembly.
NOTE: Ensure no clearance exists between gear carrier and
adjusting shim.
4) Install side bearing shims and differential case assembly
in differential carrier. Using brass drift, tap shims to fit them to
side bearing outer race. Install bearing caps. Check ring gear
backlash.
RING GEAR BACKLASH
1) Lock drive pinion in place. Using dial indicator, check
ring gear backlash at heel of ring gear tooth. Measure at 4 locations
of ring gear. Gear backlash must be within .004-.006" (.10-.15 mm).
2) If not within specification, change side bearing adjusting
shims and recheck backlash. If backlash is too small, install thinner
shim behind ring gear and thicker shim opposite ring gear.
3) If backlash is excessive, install thicker shim behind ring
gear and thinner shim opposite ring gear. Check gear tooth contact
using paint impression method.
CAUTION: When changing shims, total thickness of all shims must
remain constant.
RING GEAR RUNOUT
Using dial indicator, measure runout at back side of ring
gear. Runout must be within .002" (.05 mm). If runout is excessive,
change ring gear-to-differential case mounting position. Recheck
runout. Install cover and gasket.

thickness into left side axle housing. Install left axle shaft
assembly into axle housing and tighten nuts to specification. See
TORQUE SPECIFICATIONS table at the end of this article.
2) Install right axle shaft assembly into axle housing
WITHOUT a shim or "O" ring. Temporarily tighten nuts in diagonal
sequence to 51.6 INCH lbs. (5.8 N.m) in 2 stages. Measure clearance
between bearing case and rear axle housing end with a feeler gauge.
3) Select shims equal to the sum of the thickness of the
measured clearance plus .0020-.0079" (.05-.20 mm). Remove right axle
shaft and install the selected shim(s) and "O" ring into right axle
housing end. Install right axle shaft assembly into rear axle housing.
Tighten nuts in diagonal sequence to specification. See TORQUE
SPECIFICATIONS table.
4) Using dial indicator, check end play of axle shaft. End
play must be .0020-.0079" (.05-.20 mm). If end play is not within
specification, change shim(s) to obtain correct end play. Reverse
removal procedure to install remaining components. Adjust parking
brake and bleed brake system.
DIFFERENTIAL CARRIER
Removal
Raise and support vehicle. Drain gear oil. Mark drive shaft
flange-to-pinion flange position. Remove drive shaft. Remove axle
shafts. See AXLE SHAFTS under REMOVAL & INSTALLATION. Support
differential carrier with jack. Remove differential carrier retaining
nuts. Remove differential carrier.
Inspection
Inspect for leakage at vent plug, differential carrier
companion flange and where carrier joins axle housing.
Installation
Apply sealant to axle housing surface. To install, reverse
removal procedure. Align marks on drive shaft and pinion flange.
DRIVE SHAFT
Removal
Make match marks on drive shaft yoke flange and pinion
flange. Remove bolts. Remove drive shaft from vehicle.
Installation
To install, reverse removal procedure. Ensure match marks are
aligned. Tighten bolts to specification. See TORQUE SPECIFICATIONS
table at end of article.
OVERHAUL
AXLE SHAFTS
Disassembly
1) Mount backing plate and axle shaft assembly in soft-jawed
vise. Bend over axle shaft bearing lock washer. Using Spanner Wrench
(MD990785), remove lock nut from axle shaft. Remove washers. Reinstall\
lock nut on axle shaft approximately 3 turns.
2) Attach Bearing Puller (MB990787-01) to rear of backing
plate to remove bearing case from axle shaft. See Fig. 2. Using equal
pressure to avoid binding, tighten puller nuts diagonally to remove
bearing case. Using hammer and drift, remove bearing outer race from
bearing case. Remove oil seal from end of axle housing with Slide
Hammer and Adapter (MB990211).