1991 MITSUBISHI MONTERO check engine

install, reverse removal procedure using new gaskets and "O" rings.
Coat "O" ring with fuel before installation.
2) Install lower intake manifold gasket with adhesive side
toward intake manifold and gasket protrusions facing outboard of
engine. Tighten bolts and nuts to specification. See appropriate
TORQUE SPECIFICATIONS table at end of article. Check for fuel leaks.
TURBOCHARGER
Removal (Front)
1) Drain coolant, and remove radiator. Disconnect exhaust
pipe from turbo. Remove all air intake pipes. Note match marks and
installation depth on air pipes and hoses for reinstallation. Remove
serpentine drive belt. Remove alternator. Remove A/C compressor and
bracket, and support aside.
2) Remove O2 sensor. Remove dipstick assembly and turbo heat
shield. Disconnect turbo coolant feed and return lines. Disconnect
turbo oil feed and return lines. Remove turbocharger assembly.
Removal (Rear)
1) Drain coolant. Remove battery. Disconnect accelerator
cable at bracket and throttle body. Disconnect exhaust pipe from
turbo. Remove all air intake pipes and heat shields. Disconnect
accelerator cable at pedal.
2) Remove clutch booster vacuum hose. Remove O2 sensor.
Remove EGR pipe and turbo heat shield. Disconnect turbo coolant feed
and return lines. Disconnect turbo oil feed and return lines. Remove
turbocharger assembly.
CAUTION: DO NOT allow foreign material into turbocharger air intakes
or coolant and oil passages.
Inspection (Front & Rear)
1) Inspect turbocharger for oil leakage. Check turbine and
compressor wheels for cracks and other damage. Both wheels should turn
easily by hand.
2) Apply 6.8 psi (61 kPa) vacuum to wastegate diaphragm.
Ensure wastegate operates and diaphragm holds vacuum pressure. Use
care when cleaning gasket surfaces so no foreign material enters
turbocharger oil, coolant and air passages.
Installation (Front & Rear)
Refill turbocharger with clean engine oil through oil pipe
installation hole. To complete installation, reverse removal
procedure. Align match marks, and install air pipes and hoses to
proper depth.
EXHAUST MANIFOLDS
Removal (Montero & Pickup)
1) Remove splash shields. Remove O2 sensor. Remove exhaust
pipe-to-manifold nuts. Lower exhaust pipe, and remove gasket. Remove
heat protector. To remove right exhaust manifold, remove air duct,
engine lift bracket and alternator bracket.
2) To remove left exhaust manifold, remove EGR pipe and
gasket. Remove front intake manifold plenum bracket. Remove exhaust
manifolds and gaskets.
Inspection (Montero & Pickup)
Clean all gasket mating surfaces. Inspect for damage and
cracks on all mounting surfaces. Check mounting surfaces of manifold
and cylinder head for warpage. Repair or replace components if warpage
exceeds .012" (.30 mm).

TIMING BELT under REMOVAL & INSTALLATION. Remove intake camshaft
sprockets.
4) Remove coolant manifold and coolant inlet pipe. Using
Socket (MD998051), remove cylinder head bolts. Remove cylinder head
and camshaft assemblies. Note direction of washer installation on head
bolts.
Inspection (DOHC)
Check cylinder head height. Check warpage at gasket and
manifold surfaces. Resurface head if warpage exceeds specification.
See CYLINDER HEAD (DOHC) table under ENGINE SPECIFICATIONS at end of
article. After resurfacing, recheck cylinder head height. Replace
cylinder head if it is not within specification.
Installation (DOHC)
1) Ensure mating surfaces are clean and dry. Note
identification mark located on front of head gasket. Identification
marks are: "R" for SOHC, "2DN" for DOHC non-turbocharged and "2DT" for
DOHC turbocharged engine. Install head gasket with identification mark
toward timing belt side of engine and facing upward. Ensure all holes
are aligned.
NOTE: Install head gasket with identification mark toward timing
belt side of engine and facing upward. Ensure all holes
align. Install washers on head bolts with chamfered side
toward bolt head.
2) Install cylinder head and bolts. Ensure washers are
installed on head bolts with chamfered side toward bolt head. Using
proper sequence, tighten bolts to specification in 2-3 steps. See
Fig. 5 . See TORQUE SPECIFICATIONS (3000GT) table at end of article. On
turbocharger equipped engines, back off head bolts once, and repeat
tightening procedure.
3) To reinstall camshaft sprocket, hold hexagonal area of
camshaft using wrench while tightening sprocket bolt. Tighten rocker
cover bolts in a crisscross pattern. Start at 4 corners of rocker
cover and move toward center.
NOTE: Rocker cover bolts are color coded. Front cylinder bank
bolts are black; rear cylinder bank bolts are green.
4) To complete installation, reverse removal procedure.
Tighten bolts and nuts to specification. See TORQUE SPECIFICATIONS
(3000GT) table.
FRONT CRANKSHAFT OIL SEAL
Removal & Installation
Remove timing belt and crankshaft sprocket. See TIMING BELT
under REMOVAL & INSTALLATION. Pry oil seal from oil pump. To install,
coat seal lip with grease. Using Seal Installer (MD998717), install
seal in oil pump. Install remaining components. See appropriate TORQUE
SPECIFICATIONS table at end of article.
TIMING BELT
Removal (Montero & Pickup)
1) Drain cooling system. Disconnect upper radiator hose.
Remove upper radiator shroud. Remove cooling fan and fan clutch
assembly. Remove cooling fan pulley. Remove all drive belts. Remove
power steering pump with pressure and return hoses connected, and set
aside.
2) Remove power steering pump brackets. Remove A/C tensioner

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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.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.