tow MITSUBISHI MONTERO 1991 Service Manual

* Wrap shop towels around fuel return and high pressure hoses
to prevent fuel splashing on engine. Disconnect fuel return
hose and high pressure fuel hose to drain any residual fuel.
ENGINE
Removal (Montero & Pickup)
1) Remove hood. Drain cooling system, and remove radiator.
Remove skid plate and splash shields. Release fuel system pressure.
See FUEL PRESSURE RELEASE under REMOVAL & INSTALLATION. Disconnect
negative battery cable.
2) Remove air cleaner ducts. Remove accessory drive belts.
Remove and support A/C compressor and power steering pump. DO NOT
disconnect hoses from compressor or pump. Disconnect oil cooler hoses.
Cover fuel hose using shop towel, and disconnect high pressure fuel
hose and "O" ring. Remove fuel return hose.
3) Label and disconnect all vacuum hoses. Disconnect cooling
system hoses. Label and disconnect all electrical connections from
engine. Remove heat shield from motor mounts. Remove motor mount
bolts. Ensure all hoses and wires are disconnected and set aside.
4) Disconnect exhaust pipe from exhaust manifolds. Remove
starter. Attach engine hoist to engine. Support transmission.
Disconnect engine from transmission. See appropriate article in
CLUTCHES or TRANSMISSION SERVICING. Remove engine.
Installation (Montero & Pickup)
To install, reverse removal procedure. Install new "O" ring
on fuel line. Install new exhaust gaskets and nuts. See TORQUE
SPECIFICATIONS (MONTERO & PICKUP) table at end of article. Adjust
fluid levels.
Removal (3000GT)
1) Release fuel pressure. See FUEL PRESSURE RELEASE under
REMOVAL & INSTALLATION. Remove hood. Remove cruise control vacuum pump
and linkage. On turbo models, remove necessary turbo air intake hoses
and pipes. On all other models, remove air cleaner hoses.
2) On all models, drain cooling system. Drain engine oil and
transaxle oil. Remove heater hoses and radiator hoses. Remove
transaxle assembly. See appropriate article in CLUTCHES or
TRANSMISSION SERVICING.
3) Remove radiator. Label and disconnect all vacuum hoses.
Label and disconnect all electrical connections and harnesses from
engine. Remove accessory drive belts.
4) Remove and support A/C compressor and power steering pump.
DO NOT disconnect hoses from compressor or pump. Cover fuel hose using
shop towel, and disconnect high pressure fuel hose and "O" ring.
Remove fuel return hose.
5) On turbo models, disconnect oil cooler and vacuum hoses.
On all models, remove motor mount bolts and brackets. Ensure all hoses
and wires are disconnected and set aside. Attach engine hoist to
engine. Remove engine.
Installation
To install, reverse removal procedure. Install new "O" ring
on fuel line. Install new exhaust gaskets and nuts. See TORQUE
SPECIFICATIONS (3000GT) table at end of article. Adjust fluid levels.
UPPER INTAKE MANIFOLD
Removal (Montero & Pickup)
1) Remove air intake hose. See Fig. 1. Remove accelerator
cable adjusting bolts. On models equipped with automatic transmission,
remove throttle control cable. On all models, remove accelerator

released before disconnecting fuel lines.
Removal
1) Release fuel pressure. See FUEL PRESSURE RELEASE under
REMOVAL & INSTALLATION. Remove upper intake manifold. See UPPER INTAKE
MANIFOLD under REMOVAL & INSTALLATION.
2) Drain cooling system. Remove high pressure and return fuel
lines. Cover fuel lines using shop towel during removal as some fuel
may be retained. Remove vacuum hose from pressure regulator.
Disconnect injector harness from injectors.
3) Remove fuel delivery pipe, fuel injectors and pressure
regulator. See Fig. 3. DO NOT allow injectors to fall from delivery
pipe during removal. Remove vacuum hose and pipe assembly.
4) On Montero & Pickup, disconnect coolant temperature
sending unit, coolant temperature switch (A/C equipped), coolant
temperature sensor and thermoswitch (A/T equipped). Disconnect upper
radiator and coolant by-pass hoses. Disconnect heater pipe. On all
models, remove intake manifold and gasket.
Fig. 3: Exploded View of Lower Intake Manifold & Components
Courtesy of Mitsubishi Motor Sales of America, Inc.
Inspection & Installation
1) Inspect for damage and cracks on all mounting surfaces. To

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).

surfaces. Resurface head if warpage exceeds specification. See
CYLINDER HEAD (SOHC) table under ENGINE SPECIFICATIONS at end of
article. Replace cylinder head if it is not within specification after
resurfacing.
Installation (SOHC)
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 appropriate TORQUE SPECIFICATIONS table at end of article.
3) Apply sealant to rocker cover sealing surfaces before
installation. See Fig. 6. Ensure rocker cover gasket projections are
aligned with notches in rocker cover. Coat all "O" rings with oil, and
install a new "O" ring on distributor adapter and oil dipstick tube.
4) Coat camshaft area with oil prior to installing
distributor adapter. To complete installation, reverse removal
procedure. Tighten bolts and nuts to specification. See appropriate
TORQUE SPECIFICATIONS table. After engine reaches normal operating
temperature, allow engine to cool, and retighten cylinder head bolts.
Fig. 6: Applying Sealant to Rocker Cover (SOHC)
Courtesy of Mitsubishi Motor Sales of America, Inc.
Removal (DOHC)
1) Drain cooling system. Remove upper and lower intake
manifolds and brackets. See UPPER INTAKE MANIFOLD and LOWER INTAKE
MANIFOLD under REMOVAL & INSTALLATION.
2) Remove turbocharger(s) (if equipped). See TURBOCHARGER
under REMOVAL & INSTALLATION. Remove heat shields from exhaust
manifolds. Remove exhaust manifolds. See EXHAUST MANIFOLDS under
REMOVAL & INSTALLATION.
3) Remove spark plug wires and ignition coils. Remove rocker
cover and gasket. Remove timing belt and timing belt inner covers. See

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

2) Inspect camshaft and distributor gear for damage. Measure
camshaft end play, journal diameter and lobe height. Replace camshaft
if it is not within specification. See CAMSHAFT (SOHC) table under
ENGINE SPECIFICATIONS at end of article.
3) Coat components with oil. Reassemble rocker arms, springs
and bearing caps. Install bearing caps with identification number
toward camshaft sprocket. Ensure oil holes and notch of shafts are
properly positioned. See Fig. 19.
ROCKER ARM & SHAFT SPECIFICATIONS TABLE (SOHC)









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Application In. (mm)
Oil Clearance ................. ( 1).0004-.0016 (.010-.041)
Rocker Arm I.D. ............................ .7444 (18.91)
Rocker Arm Shaft O.D. ...................... .7440 (18.90)
Spring Free Length ......................... 2.173 (55.19)
( 1) - Maximum clearance is .0039" (.099 mm).









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Fig. 20: Installing Rocker Arm Shafts (SOHC)
Courtesy of Mitsubishi Motor Sales of America, Inc.
Installation
1) Coat camshaft with oil, and install in cylinder head.

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

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.

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A/C C O M PR ESSO R O IL C HEC KIN G

1991 M it s u bis h i M onte ro
1991 GENERAL SERVICING
Compressor Refrigerant Oil Checking
ISOLATING COMPRESSOR
NOTE: Only compressors with stem-type service valves can be
isolated.
1) Connect service gauge set to the compressor service valves
and open compressor valves slightly (turn in clockwise). Start engine
and operate air conditioning. Slowly turn compressor suction valve
clockwise toward closed (front-seated) position.
2) When suction pressure is reduced to zero or less, turn off
engine and compressor and quickly turn suction valve stem in to full
front-seated position. Suction pressure should be slightly above zero.
Turn discharge valve into front-seated position.
3) To check oil level, slowly open compressor crankcase plug
to relieve any remaining pressure. After oil level is corrected, cap
service gauge ports on both valves. Back-seat suction service valve to
allow refrigerant to enter compressor. Open discharge valve halfway.
4) Loosen discharge service valve cap, allowing refrigerant
pressure to force air out of compressor. Back-seat service valve and
tighten cap. Compressor is now ready for operation.
REFRIGERANT OIL
Only new, pure, moisture-free refrigerant oil should be used
in the air conditioning system. This oil is highly refined and
dehydrated to a point where moisture content is less than 10 parts per
million. The oil container must be tightly closed at all times when
not in use, or moisture will be absorbed into the refrigerant oil from
the air.
SERVICING PRECAUTIONS
NOTE: Recent findings by the EPA indicate that refrigerant is
harmful to the earth's protective Ozone layer. When
discharging refrigerant, DO NOT allow refrigerant to enter
the atmosphere. If available, use refrigerant
recovery/recycle systems when discharging system. Always
follow manufacturer's instructions.
DISCHARGING SYSTEM PRECAUTIONS
If compressor has stem-type service valves, it can be
isolated and removed without discharging entire system. See ISOLATING
COMPRESSOR at the beginning of this article. Otherwise, discharge
system completely before loosening any fittings.
DISCONNECTING LINES & FITTINGS TEST
After system is discharged, carefully clean area around all
fittings to be opened. Always use 2 wrenches when tightening or
loosening fittings to avoid twisting or distorting lines. Cap or plug
all openings as soon as lines are removed. DO NOT remove caps until
immediately before connections are made. This will keep entry of air