1991 MITSUBISHI MONTERO oil type

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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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

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A/C C O M PR ESSO R S ER VIC IN G

1991 M it s u bis h i M onte ro
1991 GENERAL SERVICING
Compressor Service
* PLEASE READ THIS FIRST *
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
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.
DISCHARGING SYSTEM PRECAUTIONS
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
If compressor has stem-type service valves, it can be
isolated and removed without discharging entire system. Otherwise,
discharge system completely using approved refrigerant
recovery/recycling equipment 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

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A/C -H EA TE R S YSTE M - M AN UAL

1991 M it s u bis h i M onte ro
1991 MANUAL A/C-HEATER SYSTEMS
Chrysler Motors, Mitsubishi
Chrysler Motors: Colt Vista, Ram-50
Mitsubishi: Montero, Pickup
* PLEASE READ THIS FIRST *
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
A/C SYSTEM SPECIFICATIONS
SPECIFICATIONS TABLE








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Compressor Type
Colt Vista & Montero .................... Nippondenso 10-Cyl.
Pickup & Ram-50 ............................... Sanden Scroll
Compressor Belt Deflection
Colt Vista ............................ 11/32-7/16" (8-11 mm)
Montero ............................. 21/64-3/8" (8.5-9.5 mm)
Pickup & Ram-50 .................... 21/64-25/64" (8.5-10 mm)
Compressor Oil Capacity
Colt Vista & Montero ............................... 2.7 ozs.
Pickup & Ram-50 .................................... 5.0 ozs.
Refrigerant (R-12) Capacity
Colt Vista & Montero ................................ 32 ozs.
Pickup & Ram-50 ..................................... 30 ozs.
System Operating Pressures (1)
Colt Vista, Pickup & Ram-50
High Side .................... 130-220 psi (9.1-15.5 kg/cm
)
Low Side ........................ 20-26 psi (1.4-1.8 kg/cm)
Montero
Dual Unit
High Side .................. 142-199 psi (9.9-14.0 kg/cm
)
Low Side ...................... 16-30 psi (1.1-2.1 kg/cm)
Single Unit
High Side ................... 102-142 psi (7.1-9.9 kg/cm
)
Low Side ...................... 18-32 psi (1.3-2.2 kg/cm)
(1) - With ambient temperature at least 80
F (27C).








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DESCRIPTION
Slight variations exist among the manual A/C-heater systems
used. Either Sanden Scroll or Nippondenso 10-cylinder compressor is
used. Cycling of the compressor clutch is controlled by switches which
monitor temperatures and pressures.
Compressors will only operate within the normal operating
temperatures and pressures set for each model. An electric condenser
fan operates whenever A/C system is operating. System components used
vary depending upon model. Most systems include an A/C compressor
control unit, fan switch, evaporator, temperature sensor, high and low
(or dual) pressure switch, engine coolant temperature switch,
compressor, condenser, receiver-drier and various pipes and hoses.

Connector missing ....... C ............ Require replacement.
Inoperative ............. A ........ (2) Require replacement.
Insulation overheated ... A ............ Require replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 1) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
( 1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Inoperative includes intermittent operation or out of
OEM specification.









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BLOWER SWITCHES
See SWITCHES.
CABIN AIR FILTERS
CABIN AIR FILTER INSPECTION








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Condition Code Procedure
Air flow obstruction .... A ............. Require cleaning or
replacement.
Maintenance intervals ... 3 ............ Suggest replacement.
Missing ................. C ............ Require replacement.









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CIRCUIT BREAKERS
See FUSES, FUSIBLE LINKS AND CIRCUIT BREAKERS .
COMPRESSOR CLUTCH ASSEMBLIES
COMPRESSOR CLUTCH ASSEMBLY INSPECTION








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Condition Code Procedure
Air gap incorrect ....... B .. Require repair or replacement.
Bearing seized .......... A .. Require replacement of bearing
or assembly.
Bearing worn, affecting
performance ............ A .. Require replacement of bearing
or assembly.
Coil shows signs of
overheating ............ 1 .... Suggest replacement of coil.
Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking .......... A .. Require repair or replacement.
Connector melted,

Bracket broken, affecting
performance ............ A ............ Require replacement.
Bracket broken, not
affecting performance .. .. ........ No service suggested or
required.
Bracket corroded,
affecting performance .. A .. Require repair or replacement.
Bracket corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Bracket cracked, affecting
performance ............ A .. Require repair or replacement.
Bracket cracked, not
affecting performance .. 1 .. Suggest repair or replacement.
Bracket holes elongated,
affecting performance .. A .. Require repair or replacement.
Bracket holes elongated,
not affecting
performance ............ .. ........ No service suggested or
required.
Bracket loose, affecting
performance ............ A .. Require repair or replacement.
Bracket loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Bracket missing ......... C ............ Require replacement.
Housing broken, affecting
performance ............ A .. Require repair or replacement.
Housing broken, not
affecting performance .. .. ........ No service suggested or
required.
Housing cracked, affecting
performance ............ A .. Require repair or replacement.
Housing cracked, not
affecting performance .. 1 .. Suggest repair or replacement.
Inoperative ............. A ........... (1) Require repair or
replacement.
Leaking ................. A .. Require repair or replacement.
Noisy ................... 2 ........... ( 2) Suggest repair or
replacement.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
Tubing connection
leaking ................ A .. Require repair or replacement.
( 1) - Inoperative includes intermittent operation or out of
OEM specification.
( 2) - Compressor noise can also be caused by low oil level,
state of charge, air contamination, or type of
refrigerant.









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CONDENSER AIR SEALS
CONDENSER AIR SEAL INSPECTION








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Condition Code Procedure
Leaking ................. A . Require repair or replacement.
Missing ................. C ........... Require replacement.









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CONDENSER FAN MOTORS

missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Contaminated, affecting
performance ............ A ............ Require replacement.
Dessicant bag
deteriorated ........... A ........ (1) Require replacement.
Further inspection required.
Dessicant at the end of
its useful life (saturated
with moisture) ......... 1 .. Suggest repair or replacement.
Fusible plug leaking .... A .... Require replacement of plug.
Leaking ................. A ............ Require replacement.
Pressure relief device
leaking ................ A . Require replacement of pressure
relief device.
Restricted .............. A .. Require repair or replacement.
Sight glass no longer
transparent ............ 2 ... Suggest replacement of drier.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
Tubing connection
leaking ................ A .. Require repair or replacement.
( 1) - Inspect system to determine effects of dessicant bag
deterioration.









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REFRIGERANT
NOTE: Refrigerants include any SNAP (Significant New Alternative
Policy)-approved blends.
REFRIGERANT INSPECTION









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Condition Code Procedure
Contaminated (other than
refrigerant blends) .... B ........ Require service to remove
contamination.
Different types of
refrigerants in the same
system (other than
refrigerant blends) .... B ................. Require repair.
Overcharged ............. B ................. Require repair.
Refrigerant type
does not match
fittings and label ..... B ................. Require repair.
Undercharged ............ B ................. Require repair.









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REFRIGERANT OIL
REFRIGERANT OIL INSPECTION








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Condition Code Procedure
Contaminated ............ 1 .. Require repair or replacement.
Overfilled .............. B ................. Require repair.

system is in operation. This high pressure could rupture can
or fitting at safety can valve, resulting in damage and
personal injury.
CONNECTING LINES & FITTINGS
A new "O" ring should be used in all instances when
connecting lines and fittings (dip "O" ring in clean refrigeration oil
and make certain it is not twisted during installation). Always use
two wrenches to avoid twisting or distorting lines and fittings,
tighten coupling nuts securely.
PLACING SYSTEM IN OPERATION
After component replacement and/or system servicing has been
completed and all connections have been made, proceed as follows:
1) Evacuate the system using a vacuum pump.
2) Charge the system with new R-12 (refrigerant) according t\
o
each individual vehicle as outlined in the
GENERAL COOLING SYSTEM SERVICING article. Also see Refrigerant
Capacity in this Section.
3) Leak test the system, with particular attention to all new
connections and components.
4) Make a performance test of the system. Never assume that a
recharging has automatically corrected a problem.
COMPRESSOR REMOVAL INFORMATION - ISOLATION METHOD
On systems which have compressors equipped with stem-type
service valves (Tecumseh), it is possible to isolate the compressor
for removal.
Isolating
Turn both high and low pressure manual valves to extreme
clockwise (front seat) position. Loosen cap on high pressure manual
valve connection to compressor and allow gas to escape until
compressor is relieved of pressure.
COMPRESSOR REMOVAL INFORMATION - DISCHARGE METHOD
This procedure is to be used on vehicles which have
compressor equipped with Schrader service valves. In these cases, the
compressor cannot be isolated and the system must be discharged, using
approved refrigerant recovery/recycling equipment, prior to compressor
removal.