1991 MITSUBISHI MONTERO battery

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3.0 L V 6 - V IN S [ B ,C ,S ]

1 991 M it s u bis h i M onte ro
1991 ENGINES
Mitsubishi 3.0L V6
Montero, Pickup, 3000GT
* PLEASE READ THIS FIRST *
NOTE: For engine repair procedures not covered in this article,
see ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION article
in the GENERAL INFORMATION section.
ENGINE IDENTIFICATION
Engine may be identified by using Vehicle Identification
Number (VIN) stamped on a metal pad, located near lower left corner of\
windshield. The eighth character identifies the engine model.
Engine model number is stamped on front upper edge of
cylinder block (below cylinder head) or on vehicle information plate
on firewall. Engine serial number is stamped near the engine model
number.
ENGINE IDENTIFICATION CODES TABLE









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Application Engine Model Engine Code
3.0L V6 SOHC
Montero ............... 6G72 .................... S
Pickup ................ 6G72 .................... S
3.0L V6 DOHC
3000GT
Non-Turbo ............ 6G72 .................... B
Turbo ................ 6G72 .................... C









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ADJUSTMENTS
VALVE CLEARANCE ADJUSTMENT
NOTE: Hydraulic lash adjusters are set into rocker arms (SOHC) or
cylinder head (DOHC). No adjustment is required.
REMOVAL & INSTALLATION
NOTE: For reassembly reference, label all electrical connectors,
vacuum hoses and fuel lines before removal. Also place
mating marks on engine hood and other major assemblies
before removal.
FUEL PRESSURE RELEASE
Perform these steps to release fuel system pressure:
* Disconnect fuel pump harness connector at fuel tank.
* Start engine. After it stalls, turn ignition switch to OFF
position.
* Disconnect battery (-) terminal, and reconnect fuel pump
harness connector.

* 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

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).

COMPRESSOR CLUTCH
Disconnect wiring to compressor clutch. Connect battery
voltage directly to A/C compressor clutch wiring harness connector
terminals. If a click is heard, clutch engagement is okay. If click is
not heard, pulley and armature are not making contact. Repair or
replace as necessary.
REAR BLOWER SWITCH
Montero
With blower switch in position indicated in REAR BLOWER
SWITCH CONTINUITY TEST table, ensure continuity exists between
terminals listed. See Fig. 8.
REAR BLOWER SWITCH CONTINUITY TEST TABLE









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Switch Terminal
Position Numbers Continuity
OFF ................. 1-6 ................. No
Low .............. 1, 2 & 6 .............. Yes
Medium 1 ......... 1, 3 & 6 .............. Yes
Medium 2 ......... 1, 4 & 6 .............. Yes
High ............. 1, 5 & 6 .............. Yes









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Fig. 8: Identifying Rear Blower Switch Terminals (Montero)
Courtesy of Mitsubishi Motor Sales of America.
REFRIGERANT TEMPERATURE SENSOR
Disconnect refrigerant temperature sensor electrical
connector. Using an ohmmeter, measure resistance between terminals. At

77F (25C) resistance should be approximately 80,470 ohms. If
resistance deviates greatly, replace sensor.
RELAYS
4-Terminal Relay
1) Either round or square relays may be used. Testing is same
for either relay. Remove relay from holder. Using an ohmmeter, ensure
continuity exists between terminals No. 2 and 4 and does not exist
between terminals No. 1 and 3. See Fig. 9.
2) Connect battery voltage to terminal No. 2, and ground
terminalNo. 4. Ensure continuity exists between terminals No. 1 and 3.
If continuity is not as specified, replace relay.
Fig. 9: Testing 4-Terminal Relays
Courtesy of Mitsubishi Motor Sales of America.
6-Terminal Relay
Remove relay from holder. Using an ohmmeter, ensure

continuity exists between terminals No. 2 and 5 and terminals No. 1
and 3 and does not exist between terminals No. 3 and 6. Connect
battery voltage to terminal No. 2, and ground terminal No. 5. Ensure
continuity exists between terminals No. 3 and 6 and does not exist
between terminals No. 1 and 3. See Fig. 10. If continuity is not as
specified, replace relay.
Fig. 10: Testing 6-Terminal Relay
Courtesy of Mitsubishi Motor Sales of America.
REMOVAL & INSTALLATION
NOTE: For removal and installation procedures not covered in this

Eclipse & Galant ............. TEST NO. 2
2.4L
Pickup & Ram-50 .............. TEST NO. 1
3.0L
Montero, Pickup, Ram-50,
Stealth & 3000GT ............ TEST NO. 2









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Test No. 1
1) Loosen throttle cable. Turn ignition on for more than 15
seconds. DO NOT start engine. Turn ignition off. This should fully
retract ISC motor plunger.
2) On 2.0L Galant (VIN V), connect jumper wire between
ignition timing adjustment connector and ground. See IGNITION TIMING
ADJUSTMENT CONNECTOR LOCATION table under IGNITION TIMING.
3) On all models, disconnect harness connector(s) from Idle
Speed Control (ISC) motor. Ensure ISC plunger is in fully retracted
position. Unscrew fixed Speed Adjusting Screw (SAS) until throttle
valve is fully closed. See Fig. 1.
CAUTION: When cleaning throttle body, plug air by-pass hole in
throttle body to prevent solvent from entering passage.
4) Start engine. Check basic idle speed. See IDLE SPEED
SPECIFICATIONS table. If basic idle speed is within specification, go
to step 7). If basic idle speed is not within specification, remove
air intake hose and clean throttle body. Reconnect air intake hose.
Recheck basic idle speed.
5) If basic idle speed is still not within specification
after cleaning throttle body, adjust basic idle speed by turning idle
speed adjusting screw. See Fig. 1. After adjusting basic idle speed,
turn fixed SAS screw clockwise until engine speed begins to increase.
6) Turn fixed SAS screw counterclockwise until engine speed
decreases. Turn fixed SAS screw counterclockwise an additional 1/2
turn from point at which engine speed no longer decreases. Turn off
engine.
7) Adjust throttle cable. Reconnect harness connector(s) at
ISC motor. Start engine. Operate engine for about 5 minutes. Ensure
engine idles within curb idle speed specification. See IDLE SPEED
SPECIFICATIONS table.
8) Turn ignition off. Disconnect negative battery cable for
at least 10 seconds to clear diagnostic trouble code. Reconnect
negative battery cable. Operate engine at idle for about 5 minutes to
ensure engine idles smoothly.
Test No. 2
1) Locate ignition timing adjustment connector. See IGNITION
TIMING ADJUSTMENT CONNECTOR LOCATION table under IGNITION TIMING.
Connect jumper wire between ignition timing adjustment connector and
ground.
2) Locate diagnostic connector under instrument panel.
Connect jumper wire between diagnostic connector terminal No. 10
(White wire) and ground. See Fig. 3. Start engine. Check basic idle
speed. See IDLE SPEED SPECIFICATIONS table. If basic idle speed is
within specification, go to step 9). If basic idle speed is not within
specification, go to step 3).
3) Remove air intake hose. Check throttle body. If throttle
body contains deposits, go to next step. If throttle body is clean,
disconnect jumper wires connected in steps 1) and 2). On all models
except Eclipse, Galant and Mirage, go to step 6). On Eclipse, Galant
and Mirage, go to step 5).
CAUTION: When cleaning throttle body, plug air by-pass hole in

NOTE: Idle mixture is computer controlled on fuel injected engines
and is nonadjustable. CO level specifications are not
available from manufacturer.
THROTTLE POSITION SENSOR (TPS)
TPS ADJUSTMENT
NOTE: Ensure basic idle speed is set to specification before
adjusting TPS. See BASIC IDLE SPEED under IDLE SPEED &
MIXTURE. Perform all adjustments with engine at normal
operating temperature, front wheels in straight-ahead
position, cooling fan and all accessories off, and
transmission in Park or Neutral.
TPS TEST APPLICATION









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Application Test
1.5L
Colt, Colt 200,
Mirage & Summit ............. TEST NO. 1
1.6L
Mirage ....................... TEST NO. 2
1.8L
Eclipse ...................... TEST NO. 3
2.0L (VIN V)
Colt Vista & Galant .......... TEST NO. 1
2.0L (VIN R & U)
Galant ....................... TEST NO. 1
Eclipse ...................... TEST NO. 3
2.4L
Pickup & Ram-50 .............. TEST NO. 1
3.0L
Montero, Pickup & Ram-50 ..... TEST NO. 4
Stealth & 3000GT ............. TEST NO. 5









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Test No. 1
1) Turn ignition on for more than 15 seconds. DO NOT start
engine. Turn ignition off. ISC plunger should be retracted fully.
2) Ensure ISC plunger is in fully retracted position.
Disconnect harness connector(s) from ISC motor. Turn ignition on. DO
NOT start engine.
3) Using digital voltmeter, backprobe terminal No. 19
(Green/White wire) and terminal No. 24 (Black or Green/Black wire) a\
t
Engine Control Unit (ECU) wiring harness connector. Note TPS output
voltage.
4) If output voltage is .48-.52 volt, go to step 6). If
output voltage is not .48-.52 volt, loosen TPS mounting screw(s) and
rotate TPS clockwise, or counterclockwise, until output voltage is
within specification. Tighten TPS mounting screws.
5) Turn ignition off. Reconnect harness connector(s) at ISC
motor. Start engine. Ensure engine idles within curb idle speed
specification.
6) Turn ignition off. Disconnect negative battery cable for
at least 15 seconds to clear diagnostic trouble code. Reconnect
negative battery cable. Operate engine at idle for about 5 minutes to
ensure engine idles smoothly.
Test No. 2
1) Turn ignition on. DO NOT start engine. Loosen throttle