1991 MITSUBISHI MONTERO engine coolant

cable. Label and disconnect all vacuum hoses from throttle body and
upper intake manifold.
2) Disconnect O2 sensor connector. Remove EGR pipe and
gasket. Remove ignition coil. Remove engine oil filler neck bracket.
Remove throttle body, leaving coolant hoses connected. Remove throttle
body gasket. Remove upper intake manifold plenum mounting bolts and
nuts.
3) If necessary, remove EGR valve and pipe. Remove upper
intake manifold plenum brackets. Remove upper intake manifold and
gasket.
Inspection & Installation (Montero & Pickup)
Clean all gasket mating surfaces. Inspect for damage and
cracks on all mounting surfaces. To install, reverse removal procedure
using new gaskets. Tighten bolts and nuts to specification. See TORQUE
SPECIFICATIONS (MONTERO & PICKUP) table at end of article.
Fig. 1: Exploded View of Upper Intake Manifold & Components (DOHC)
Courtesy of Mitsubishi Motor Sales of America, Inc

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

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),

\003
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








\









\









\









\









\









\









\


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).








\









\









\









\









\









\









\


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.

speeds of blower operation are selected. In order for A/C system to
operate, blower motor control lever MUST be in a position other than
OFF.
MODE SELECTOR LEVER
Mode selector lever is located in upper right corner of
control panel. Either 2 or 6 modes are available to achieve desired
distribution of air from various outlets.
On all models, air is directed to windshield and side
windows and comes out from the panel outlets when mode selector lever
is positioned to the far left. When lever is moved one detent to the
right, air is directed to windshield and side windows simultaneously.
On 6-mode models, air is directed to floor area, windshield,
and side windows when lever is moved 2 detents to the right. When
lever is moved 3 detents to the right, air is directed to floor area.
When lever is moved to the second to last detent on control panel, air
is directed to floor area and panel outlets. When lever is in the far
right position, air will be directed to panel outlets only.
TEMPERATURE CONTROL LEVER
The temperature control lever operates blend-air door in the
heater/air conditioning unit, mixing cooled and heated air so the
selected air temperature can be obtained. The system will provide
cooled air when A/C switch is in ON position and blower motor is in
any position other than OFF. The temperature control lever should be
in the far left (maximum cooling) side of temperature selection scale
when maximum A/C cooling is desired.
DUAL PRESSURE SWITCH
The dual pressure switch, located in the refrigerant line
near condenser, is wired in series with compressor clutch. Whenever
system pressures drop below or increase above the control point of the
switch, power supplied to compressor will be cut and compressor
activity will cease until pressures are back to within operating
ranges.
ENGINE COOLANT TEMPERATURE SWITCH
The engine coolant temperature switch, located on thermostat
housing, is wired in series with compressor clutch. When coolant
temperature is greater than switch control temperature, power to
compressor is cut and compressor is turned off until temperature
returns to operating range.
EVAPORATOR THERMISTOR
The evaporator thermistor, attached to evaporator fins, is
wired in series with compressor clutch and prevents evaporator
freezing. Power to compressor clutch is cut if control temperature is
exceeded, allowing evaporator to thaw. When temperature returns to
operating range, thermistor allows power to compressor clutch.
FUSIBLE PLUG
A fusible plug, located on receiver-drier, melts and allows
refrigerant to escape when ambient temperatures in engine compartment
reach 221
F (105C). Once fusible plug has blown, it cannot be reused
and must be replaced.

Fig. 7: Front Blower Switch Terminal ID (Colt Vista & Montero)
Courtesy of Mitsubishi Motor Sales of America.
DUAL PRESSURE SWITCH
Montero, Pickup & Ram-50
1) Turn engine off. Disconnect harness connector at dual
pressure switch (located near condenser). Jumper harness connector.
Turn A/C switch and blower switch to ON positions. Momentarily turn
ignition on and listen for compressor clutch engagement.
2) If compressor clutch does not engage, check evaporator
thermistor and engine coolant temperature switch. Check for a faulty
fuse. Repair or replace components as necessary. If compressor clutch
engages, go to next step.
3) Connect manifold gauge set to system, and check operating
pressures. Dual pressure switch should allow compressor operation if
system pressure is 30-384 psi (2-27 kg/cm
). If dual pressure switch
does not operate within specified pressure range, discharge system
using approved refrigerant recovery/recycling equipment, and replace
switch.
4) After replacing switch, recharge system, and monitor
pressures for proper compressor operation. If dual pressure switch
cuts power to compressor clutch while driving even though temperatures
inside have not yet decreased, high pressure side of dual pressure
switch has possibly been activated. Go to next step.
5) Discharge system using approved refrigerant
recovery/recycling equipment. Replace switch, and recharge system.
Ensure compressor clutch operates within 30-384 psi (2-27 kg/cm
).
Check for sufficient system cooling.

ENGINE COOLANT TEMPERATURE SWITCH
1) Turn engine off. Disconnect connector at engine coolant
temperature switch. Jumper wires on harness side of connector. If
vehicle uses a single connector, ground connector.
2) Press A/C switch to ON position and turn blower switch to
ON position. Momentarily turn ignition on and listen for compressor
clutch engagement. Clutch should engage. If clutch does not engage,
check fuse and other components wired in series with compressor
clutch.
EVAPORATOR THERMISTOR
Disconnect connector and remove thermo relay from evaporator
core. Jumper wires on harness side connector. Turn A/C switch to ON
position and turn on blower. Momentarily turn ignition on and listen
for compressor clutch engagement. If clutch does not engage, check
fuse and other components wired in series with compressor clutch.
HIGH PRESSURE SWITCH
Colt Vista
Disconnect high pressure switch connector. Jumper wires on
harness side of connector. Momentarily turn ignition on and listen for
compressor clutch engagement. If clutch does not engage, check fuse
and other components wired in series with compressor clutch.
HIGH/LOW PRESSURE CUT-OFF SWITCH
Pickup & Ram-50
1) Turn engine off. Disconnect High/Low Pressure Cut-Off
(HLPCO) switch, located on refrigerant line near condenser. Jumper
HLPCO wiring harness connector. Turn A/C switch and blower switch to
ON positions. Momentarily turn ignition on and listen for compressor
clutch engagement.
2) If compressor clutch does not engage, check evaporator
thermistor and engine coolant temperature switch. Check for a faulty
fuse. Repair or replace as necessary. If compressor clutch engages, go
to next step.
3) Connect manifold gauge set to system, and check operating
pressures. HLPCO switch should allow compressor operation if system
pressure is 28-385 psi (1.9-27 kg/cm
). If HLPCO switch does not
operate within specified pressure range, discharge system using
approved refrigerant recovery/recycling equipment, and replace switch.
4) After replacing switch, recharge system, and monitor
pressures for proper compressor function. If HLPCO switch cuts power
to compressor clutch while driving even though temperatures inside
have not yet decreased, high pressure side of new HLPCO switch has
possibly been activated. Go to next step.
5) Discharge system using approved refrigerant
recovery/recycling equipment. Replace switch, and recharge system.
Ensure compressor clutch operates within 28-385 psi (1.9-27 kg/cm
).
Check for sufficient system cooling.
LOW PRESSURE SWITCH
Colt Vista
Disconnect low pressure switch connector. Jumper wires on
harness side of connector. Momentarily turn ignition on and listen for
compressor clutch engagement. If clutch does not engage, check fuse
and other components wired in series with compressor clutch.