1991 MITSUBISHI MONTERO engine
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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
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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
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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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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.
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OIL PRESSURE
Oil pressure should be at least 11.4 psi (.8 kg/cm) at idle
and engine oil temperature of 167-194F (75-90C).
OIL PUMP
Removal
Remove timing belt and crankshaft sprocket. See TIMING BELT
under REMOVAL & INSTALLATION. Remove oil pan. See OIL PAN under
REMOVAL & INSTALLATION. Remove oil filter and mounting bracket. Remove
oil pump and gasket from cylinder block. Note bolt length and location
for installation.
Disassembly & Inspection
1) Disassemble pump, and check for scoring and cracks.
Install rotors in pump body. Check clearance between driven rotor and
pump body. See OIL PUMP SPECIFICATIONS table. Place straightedge
across pump body to check rotor side clearance.
2) Check clearance between straightedge and both rotors.
Replace rotor set or pump assembly if not within specification. Ensure
relief valve slides freely in pump body bore. Inspect relief valve
spring for damage.
OIL PUMP SPECIFICATIONS TABLE
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Application In. (mm)
Driven Rotor-To-Pump Body ........ .0039-.0071 (.099-.180)
Rotor Side Clearance ............. .0016-.0037 (.041-.094)
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Reassembly & Installation
1) Reassemble pump. Tighten pump rear cover bolts to
specification. See appropriate TORQUE SPECIFICATIONS table in this
article. Install oil pump and gasket. Ensure splined teeth of oil pump
align with crankshaft. Install bolts, and tighten to specification.
2) If oil seal was removed, coat new seal with grease. Using
Seal Installer (MD998717), install seal in oil pump until flush with
case. Install remaining components.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE (MONTERO & PICKUP) \
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Application Ft. Lbs. (N.m)
Air Intake Plenum Stay Bolts ............... 11-14 (15-19)
Camshaft Bearing Cap Bolt .................. 14-15 (19-20)
Camshaft Sprocket Bolt ..................... 58-72 (79-98)
Connecting Rod Nut ......................... 37-38 (50-52)
Crankshaft Pulley Bolt
Montero .............................. 108-116 (146-157)
Pickup ............................... 130-137 (176-186)
Cylinder Head Bolt ( 1)
Cold Engine .............................. 65-72 (88-98)
Drive Plate Bolt ........................... 53-55 (72-75)
Exhaust Manifold Nut ....................... 11-16 (15-22)
Flywheel Bolt .............................. 53-55 (72-75)
Intake Manifold Bolts ...................... 11-15 (15-20)
Left Engine Support Bracket Bolt ........... 15-21 (20-30)
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Main Bearing Cap Bolt ...................... 55-61 (75-83)
Oil Pick-Up Tube Bolt ...................... 11-15 (15-20)
Rear Engine Support
Bracket-To-Engine Bolt .................... 13-18 (18-25)
Relief Valve Plug .......................... 29-36 (39-49)
Right Engine Support Bracket Bolt
10x22 mm ................................. 25-36 (34-49)
12x22 mm & 12x32 mm ...................... 47-61 (64-83)
Rocker Shaft ............................... 14-15 (19-20)
Timing Belt Tensioner Bolt ................. 16-21 (22-29)
Water Pump Bolt ............................ 14-20 (19-27)
INCH Lbs. (N.m)
Delivery Pipe Bolt ......................... 84-108 (9-12)
Distributor Adapter Bolt .................. 108-132 (12-15)
Oil Filter Bracket Bolt .................. 108-120 (12-14)
Oil Pan Bolt ................................. 48-60 (5-7)
Oil Pump Cover Bolt ........................ 72-108 (8-12)
Oil Pump Mounting Bolt ................... 108-120 (12-14)
Rear Seal Case Bolt ........................ 84-108 (9-12)
Rocker Cover Bolt ............................ 72-84 (8-9)
Throttle Body Bolt ......................... 84-108 (9-12)
Timing Belt Cover Bolt ..................... 84-108 (9-12)
Transmission Mounting Plate Bolt ........... 84-108 (9-12)
( 1) - Tighten in 2 steps using proper sequence.
See Fig. 4.
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TORQUE SPECIFICATIONS TABLE (3000GT) \
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Application Ft. Lbs. (N.m)
Air Intake Plenum Stay Bolts ..................... 13 (18)
Automatic Tensioner Bolt ......................... 17 (23)
Camshaft Bearing Cap Bolt ........................ 15 (20)
Camshaft Sprocket Bolt ........................... 65 (88)
Connecting Rod Nut ............................... 38 (52)
Crankshaft Pulley Bolt
SOHC ................................. 108-116 (146-157)
DOHC ................................. 130-137 (176-186)
Cylinder Head Bolt ( 1)
SOHC ................................... 76-83 (103-113)
DOHC
Non-Turbo ............................. 76-83 (103-113)
Turbo ................................. 87-94 (118-127)
Distributor Adapter Bolt ......................... 11 (15)
Drive Plate Bolt ................................. 55 (75)
Engine Support Bracket Bolt
Except 10x40 mm ........................ 76-83 (103-113)
10x40 mm ................................. 47-54 (63-73)
Exhaust Manifold Nut ............................. 13 (18)
Flywheel Bolt .................................... 55 (75)
Intake Manifold Bolt
Lower Manifold
Non-Turbo ............................... 11-15 (15-20)
Turbo .................................... 9-11 (12-15)
Upper Manifold ................................. 13 (18)
Main Bearing Cap Bolt ............................ 58 (79)
Oil Filter Bracket Bolt .......................... 11 (15)
Oil Pick-Up Tube Bolt ............................ 14 (19)
Oil Pump Mounting Bolt ........................... 11 (15)
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Rear Engine Support
Bracket-To-Engine Bolt .................... 13-18 (18-25)
Relief Valve Plug ................................ 33 (45)
Rocker Shaft ............................... 14-15 (19-20)
Roll Stopper Bracket Through Bolts ......... 36-43 (49-58)
Turbocharger-To-Exhaust Fitting ............ 40-47 (54-64)
Timing Belt Tensioner Bolt ....................... 31 (42)
Water Pump Bolt .................................. 17 (23)
INCH Lbs. (N.m)
Delivery Pipe Bolt .............................. 108 (12)
Oil Pan Bolt ................................. 48-60 (5-7)
Oil Pump Cover Bolt .............................. 96 (11)
Rear Seal Case Bolt .............................. 96 (11)
Rocker Cover Bolt
SOHC ....................................... 72-84 (8-9)
DOHC ............................................ 26 (3)
Throttle Body Bolt ......................... 84-108 (9-12)
Timing Belt Cover Bolt ..................... 84-108 (9-12)
Transmission Mounting Plate Bolt ........... 84-108 (9-12)
( 1) - Tighten in 2 steps using proper sequence.
See Fig. 4.
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ENGINE SPECIFICATIONS
GENERAL ENGINE SPECIFICATIONS
GENERAL SPECIFICATIONS TABLE \
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Application Specification
3.0L V6 DOHC Non-Turbo
Displacement ....................... 181.4 Cu. In. (3.0L)
Bore ................................... 3.587" (91.1 mm)
Stroke ................................. 2.992" (76.0 mm)
Compression Ratio ................................ 10.0:1
Fuel System ......................................... PFI
Horsepower @ RPM ............................. 222 @ 6000
Torque Ft. Lbs. @ RPM ........................ 201 @ 4500
3.0L V6 DOHC Turbo
Displacement ....................... 181.4 Cu. In. (3.0L)
Bore ................................... 3.587" (91.1 mm)
Stroke ................................. 2.992" (76.0 mm)
Compression Ratio ................................. 8.0:1
Fuel System ......................................... PFI
Horsepower @ RPM ............................. 300 @ 6000
Torque Ft. Lbs. @ RPM ........................ 307 @ 2500
3.0L V6 SOHC
Displacement ....................... 181.4 Cu. In. (3.0L)
Bore ................................... 3.587" (91.1 mm)
Stroke ................................. 2.992" (76.0 mm)
Compression Ratio ................................. 8.9:1
Fuel System ......................................... PFI
Horsepower @ RPM ............................. 143 @ 5000
Torque Ft. Lbs. @ RPM ........................ 168 @ 2500
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\003
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