1991 MITSUBISHI MONTERO Service Manual

and No. 2. Install bearing caps with front mark arrow facing the same
direction as similar mark on cylinder head beside bearing journal.
Note bearing cap number and identification mark ("I" for intake
camshaft and "E" for exhaust). See Fig. 22.
3) Install front and rear bearing caps. Tighten bearing cap
bolts to specification. See TORQUE SPECIFICATIONS (3000GT) table at
end of article. Coat camshaft oil seal area with oil. Using Seal
Installer (MD998761), install camshaft oil seal. Using Circular
Packing Installer (MD998761), install circular packing.
4) Install crankshaft angle sensor adapter. To complete
installation, reverse removal procedure. Tighten bolts to
specification. See TORQUE SPECIFICATIONS table.
REAR CRANKSHAFT OIL SEAL
Removal
Remove transaxle/transmission. See appropriate article in
TRANSMISSION SERVICING or CLUTCHES. Remove flywheel or drive plate.
Remove rear oil seal case. Pry seal from seal case.
Installation
To install, coat seal lip with oil. Using Seal Installer
(MD998718), install seal in seal case. Apply sealant to sealing
surface of seal case. Install seal case. Install flywheel or drive
plate. Tighten bolts to specification. See appropriate TORQUE
SPECIFICATIONS table at end of article. To complete installation,
reverse removal procedure.
WATER PUMP
Removal
Drain cooling system. Remove timing belt and crankshaft
sprocket. See TIMING BELT under REMOVAL & INSTALLATION. Remove coolant
pipes to water pump (if required). Remove water pump bolts, noting
length and location for reassembly reference. Remove water pump.
Installation
To install, reverse removal procedure using new gasket and
"O" rings. Coat all "O" rings with water before installation. Install
water pump and gasket. Tighten bolts to specification. See appropriate
TORQUE SPECIFICATIONS table at end of article.
OIL PAN
Removal (Montero)
1) Remove hood. Remove skid plate and lower covers. Raise and
support vehicle. Disconnect and remove exhaust pipe from exhaust
manifolds. Drain engine oil. Remove starter cover and starter. Remove
oil pressure sending unit connector. Remove front suspension
crossmember.
2) Remove transmission stays. Remove ground cable and motor
mount heat shields. Attach engine hoist. Remove motor mount bolts.
Raise engine, and insert a 1" wood spacer between front insulator and
mounts. Lower engine onto wood blocks.
3) Raise vehicle using a hoist. Remove oil pan bolts. Using
Seal Cutter (MD998727), separate oil pan from cylinder block. Remove
pan from vehicle.
Removal (Pickup)
1) Remove skid plate and lower covers. Raise and support
vehicle. Drain engine oil. Using Steering Linkage Puller (C-3894-A or
MB990635), disconnect relay rod from idler arm and steering box.
2) Remove oil pan bolts. Using Seal Cutter (MD998727),

separate oil pan from cylinder block. Remove pan from vehicle.
Removal (3000GT)
1) Raise and support vehicle. Remove engine undercovers.
Drain engine oil. Disconnect O2 sensor connector. Remove front exhaust
pipe from manifolds. On All-Wheel Drive (AWD) models, drain transfer
assembly. Remove front air dam. Remove AWD drive shaft and transfer
assembly.
2) On turbocharged models, remove oil return lines from oil
pan. On all models, remove starter. Remove crossmember and transaxle
stays. Remove bellhousing cover. Remove oil pan bolts. Using Seal
Cutter (MD998727), separate oil pan from cylinder block. Remove pan
from vehicle.
Inspection (All Models)
Clean sealant from oil pan mating surface on engine block and
oil pan. Check oil pan for cracks and damage. Check sealing surface
for damage and deformation. Inspect oil pick-up screen for damage.
Installation (All Models)
1) To install, reverse removal procedure. Apply sealant to
oil pan flange in a continuous .16" (4 mm) diameter bead. See Fig. 22.
Install oil pan within 15 minutes of applying sealant.
2) Tighten bolts to specification in proper sequence. See
appropriate TORQUE SPECIFICATIONS table at end of article. Wait at
least 30 minutes before adding oil and starting engine. On AWD models,
refill transfer assembly with GL-4 hypoid gear oil. On all models,
complete installation by reversing removal procedure.
Fig. 22: Sealant Application & Oil Pan Bolt Tightening Sequence
Courtesy of Mitsubishi Motor Sales of America, Inc.
OVERHAUL

CYLINDER HEAD
Check cylinder head height and warpage at gasket and manifold
surfaces. Resurface head if warpage exceeds specification. See
appropriate CYLINDER HEAD table under ENGINE SPECIFICATIONS at end of
article. Replace cylinder head if it is not within specification after
resurfacing.
VALVE SPRINGS
Measure free length of valve springs. Check spring pressure
at specified height. Replace springs if not within specification. See
appropriate VALVES & VALVE SPRINGS table under ENGINE SPECIFICATIONS
at end of article. Check valve spring for squareness. Replace spring
if out-of-square exceeds 4 degrees.
NOTE: Install valve springs with enamel-coated side toward valve
spring retainer.
VALVE STEM OIL SEALS
With valves removed, remove oil seals from cylinder head.
Coat new seals with oil. Using Valve Stem Oil Seal Installer (MD998377
for Montero, MD998729 for Pick-up or MD998763 for DOHC), install valve
stem oil seal.
VALVE GUIDES
1) Measure valve stem-to-guide clearance. Replace valve guide
if not within specification. See appropriate VALVES & VALVE SPRINGS
table under ENGINE SPECIFICATIONS at end of article.
2) Using rod of Valve Guide Remover/Installer (MD998115) for\
SOHC, drive out valve guide toward combustion chamber side of cylinder
head. Note length of valve guides. On DOHC, use press and
appropriately-sized rod to press valve guide toward combustion chamber
side of head.
3) On all models, cylinder head must be bored to install
oversized valve guide once guide is removed. DO NOT install valve
guide of same dimension as old guide. Bore cylinder head to
specification for oversize valve guide. See appropriate OVERSIZE VALVE
GUIDE SPECIFICATIONS table.
4) On SOHC, install proper length valve guide. Intake guide
is 1.73" (43.9 mm) long and exhaust guide is 1.89" (48.0 mm) long. O\
n
all models, position cylinder head with combustion chamber downward.
5) Using valve guide remover/installer, install valve guide.
Remover/installer sets valve guide height on SOHC. On DOHC, install
valve guide to .689" (17.5 mm), measured from cylinder head spring
seating area to top of valve guide. On all models, ensure valve slides
smoothly in valve guide. Recondition valve seat.
OVERSIZE VALVE GUIDE SPECIFICATIONS TABLE (SOHC)









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Oversize In. (mm) Size Mark Bore Size In. (mm)
.002 (.05) ............ 5 ... .5138-.5145 (13.050-13.068)
.010 (.25) ............ 25 .. .5217-.5224 (13.251-13.269)
.020 (.51) ............ 50 .. .5315-.5322 (13.500-13.518)









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OVERSIZE VALVE GUIDE SPECIFICATIONS TABLE (DOHC)








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Oversize In. (mm) Size Mark Bore Size In. (mm)
.002 (.05) ............ 5 ... .4744-.4751 (12.050-12.068)
.010 (.25) ............ 25 .. .4823-.4830 (12.251-12.269)
.020 (.51) ............ 50 .. .4921-.4928 (12.500-12.518)









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VALVE SEAT (SOHC)
1) Valve seat sinkage should be checked after valve and valve
seat have been reconditioned and lightly lapped. With valve assembly
installed, measure installed height of valve spring between spring
seat and retainer. Valve seat must be replaced if measurement exceeds
1.63" (41.4 mm).
2) Grind seat wall thickness until seat can be removed.
Machine cylinder head to accommodate an oversize valve seat. See
OVERSIZE VALVE SEAT SPECIFICATIONS (SOHC) table. Heat cylinder head to\
approximately 480
F (250C), and install valve seat. Grind valve seat
using 45-degree stone. Use 30-degree and 60-degree stones to set seat
height.
OVERSIZE VALVE SEAT SPECIFICATIONS TABLE (SOHC)









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Application In. (mm)
Intake
Bore Depth
.012" (.3 mm) Oversize ............ .311-.319 (7.9-8.1)
.024" (.6 mm) Oversize ............ .323-.331 (8.2-8.4)
Bore Diameter
.012" (.3 mm) Oversize .. 1.7440-1.7451 (44.300-44.325)
.024" (.6 mm) Oversize .. 1.7559-1.7569 (44.600-44.625)
Exhaust
Bore Depth
.012" (.3 mm) Oversize ............ .311-.319 (7.9-8.1)
.024" (.6 mm) Oversize ............ .323-.331 (8.2-8.4)
Bore Diameter
.012" (.3 mm) Oversize .. 1.5079-1.5089 (38.300-38.325)
.024" (.6 mm) Oversize .. 1.5197-1.5207 (38.600-38.625)









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VALVE SEAT (DOHC)
Grind seat wall thickness until seat can be removed. Machine
cylinder head to accommodate an oversize valve seat. See OVERSIZE
VALVE SEAT SPECIFICATIONS (DOHC) table. Chill cylinder head with
liquid nitrogen, and install valve seat. Grind valve seat using 45-
degree stone. Use 30-degree and 60-degree stones to adjust seat
height.
OVERSIZE VALVE SEAT SPECIFICATIONS TABLE (DOHC)









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Application In. (mm)
Intake
Bore Depth
.012" (.3 mm) Oversize ............ .295-.303 (7.5-7.7)
.024" (.6 mm) Oversize ............ .307-.315 (7.8-8.0)
Bore Diameter
.012" (.3 mm) Oversize .. 1.4291-1.4301 (36.300-36.325)
.024" (.6 mm) Oversize .. 1.4409-1.4419 (36.600-36.625)
Exhaust
Bore Depth

.012" (.3 mm) Oversize ............ .311-.319 (7.9-8.1)
.024" (.6 mm) Oversize ............ .323-.331 (8.2-8.4)
Bore Diameter
.012" (.3 mm) Oversize .. 1.3110-1.3120 (33.300-33.325)
.024" (.6 mm) Oversize .. 1.3228-1.3238 (33.600-33.625)









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VALVES
Disassemble cylinder head. Measure valve stem diameter, valve
margin and overall length. Replace valves if not within specification.
See appropriate VALVES & VALVE SPRINGS table under ENGINE
SPECIFICATIONS at end of article. Check valve for worn valve tip.
Measure valve margin after grinding valves.
LASH ADJUSTERS
Before installation, submerge lash adjuster in diesel fuel.
Using a small wire, hold down internal check valve. Pump plunger up
and down 4 or 5 times to bleed air from lash adjuster.
CYLINDER BLOCK ASSEMBLY OVERHAUL
CYLINDER BLOCK
1) Inspect cylinder block for cracks, warpage, cylinder bore
taper and out-of-round. Replace or repair cylinder block if it is not
within specification. See CYLINDER BLOCK table under ENGINE
SPECIFICATIONS at end of article.
2) Measure cylinder bore and piston skirt diameter. Piston
skirt diameter should be measured at 90-degree angle to piston pin.
Clearance between piston and cylinder bore must be within
specification. See appropriate PISTONS, PINS & RINGS table under
ENGINE SPECIFICATIONS at end of article.
PISTON & ROD ASSEMBLY
1) Remove cylinder heads, and remove oil pan. See CYLINDER
HEADS and OIL PAN under REMOVAL & INSTALLATION. Ensure cylinder ridge
is removed. Mark connecting rod and cap for cylinder identification.
2) Note front mark on piston and connecting rod. See Fig. 23.
Mark is positioned toward timing belt side of engine. Remove rod cap
and piston assembly.
3) Ensure piston ring end gap and side clearance are within
specification. See appropriate PISTONS, PINS & RINGS table under
ENGINE SPECIFICATIONS at end of article. Install rings on piston with
ring code identification marks toward top of piston. On DOHC, top ring
is marked "T" and No. 2 ring is marked "T2". On SOHC, top ring is
marked "T1" and No. 2 ring is marked "2R". Lubricate piston, rings and
cylinder bore with engine oil.
4) Properly space ring end gaps on piston. See Fig. 23.
Install piston and rod into cylinder bore. Ensure piston is installed
with front mark toward timing belt side of engine.
NOTE: Front mark "R" on piston indicates installation in
cylinders No. 1, 3 or 5 while front mark "L" indicates
installation in cylinders No. 2, 4 or 6. Ensure front mark
on piston and connecting rod are toward timing belt side of
engine. See Fig. 23.
5) Check bearing clearance using Plastigage method. Tighten
rod cap nuts to specification. See appropriate TORQUE SPECIFICATIONS

table at end of article. Ensure rod moves freely on crankshaft. Check
connecting rod side play. Repair or replace connecting rod if not
within specification. See CONNECTING RODS table under ENGINE
SPECIFICATIONS at end of article.
Fig. 23: Aligning Piston & Rings
Courtesy of Mitsubishi Motor Sales of America, Inc.
FITTING PISTONS

Measure cylinder bore and piston skirt diameter. Piston skirt
diameter should be measured at 90-degree angle to piston pin.
Clearance between piston and cylinder bore must be within
specification. See appropriate PISTONS, PINS & RINGS table under
ENGINE SPECIFICATIONS at end of article.
PISTON PIN REPLACEMENT
1) Note reference mark on top of piston and connecting rod.
See Fig. 23 . Using press and Piston Pin Remover/Installer (MD998184
for SOHC or MD998765 for DOHC), remove pin.
2) Inspect piston for cracks and damage. Check ring side
clearance. Replace piston if not within specification. See appropriate
PISTONS, PINS & RINGS table under ENGINE SPECIFICATIONS.
3) Check connecting rod for bend and twist. Replace
connecting rod if twist exceeds .004" (.10 mm) or bend exceeds .002"
(.05 mm). Pressure required to install pin in rod is 1686-3934 lbs.
(7500-17,500 N).
4) Position piston on connecting rod. Ensure reference marks
on top of piston and connecting rod are aligned. See Fig. 23.
Lubricate all components with oil. To install, reverse removal
procedure. Ensure piston pin is centered in piston.
NOTE: Install piston with reference mark aligned with connecting
rod reference mark. See Fig. 23.
CRANKSHAFT & MAIN BEARINGS
1) Remove flywheel or drive plate. Remove
transaxle/transmission mounting plate and rear seal case. Remove oil
pump, oil pan and oil pick-up tube. Ensure connecting rods and main
bearing cap are marked for location.
2) Remove connecting rod caps and bearings. Note direction of
arrow on main bearing cap. Remove main bearing cap. See Fig. 24.
Ensure all components are placed in correct order. Remove crankshaft.
Remove main bearings from cylinder block. Mark bearings for location.
3) Inspect crankshaft for cracks and damaged gear or threads.
Check crankshaft for taper and out-of-round. Replace or repair
crankshaft if it is not within specification. See CRANKSHAFT, MAIN &
CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS at end of
article.
4) Install upper main bearings in cylinder block. Ensure oil
hole is aligned and bearing is properly seated. Lubricate bearings
with engine oil. Install thrust bearings on No. 3 main bearing journal
with oil grooves toward crankshaft thrust surface.
5) Install crankshaft in block. Install thrust bearing on No.
3 main bearing cap with oil grooves toward crankshaft thrust surface.
Install main bearing cap with arrow toward front of engine.
6) Check oil clearance using Plastigage method. Tighten bolts
to specification in proper sequence. See Fig. 24. See appropriate
TORQUE SPECIFICATIONS table at end of article. Remove main bearing
cap. Clearance must be within specification. See CRANKSHAFT, MAIN &
CONNECTING ROD BEARINGS table. If oil clearance exceeds specification,
replace bearings or crankshaft.
7) Ensure crankshaft rotates freely with main bearing cap
installed. Check crankshaft end play. See CRANKSHAFT, MAIN &
CONNECTING ROD BEARINGS table.
8) Install connecting rod caps and bearings. Ensure
components are installed in original location. Tighten rod nuts to
specification. See appropriate TORQUE SPECIFICATIONS table. Ensure
connecting rods move freely on crankshaft. To complete installation,
reverse removal procedure. Tighten bolts to specification.

Fig. 24: Main Bearing Cap Bolt Tightening Sequence
Courtesy of Mitsubishi Motor Sales of America, Inc.
CONNECTING ROD BEARINGS
1) Mark bearing cap and connecting rod for location. Remove
connecting rod cap and bearing. Install replacement bearing.
2) Ensure reference marks on rod cap and connecting rod are
aligned. Check bearing clearance using Plastigage method. Ensure
connecting rod moves freely on crankshaft. Check connecting rod side
play. See CONNECTING RODS table under ENGINE SPECIFICATIONS at end of
article.
CRANKSHAFT END PLAY
If end play is not within specification, inspect thrust
bearings and crankshaft. Replace thrust bearing or crankshaft to
obtain correct end play. See CRANKSHAFT, MAIN & CONNECTING ROD
BEARINGS table under ENGINE SPECIFICATIONS at end of article.
ENGINE OILING
ENGINE LUBRICATION SYSTEM
Oil pressure is provided by a rotor-type pump driven by
crankshaft. Pressure relief valve is located in oil pump body.
CRANKCASE CAPACITY
Montero & Pick-up oil capacity is 5.0 qts. (4.7L). Add .5 qt.\
(.4L) with filter replacement. Add .5 qt. (.4L) with oil cooler.
3000GT oil capacity is 4.2 qts. (4.0L). Add .5 qt. (.4L) with filter\
replacement. Add .5 qt. (.4L) with oil cooler.