1991 MITSUBISHI MONTERO alternator

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).

Installation (Montero & Pickup)
To install, reverse removal procedure using new gaskets.
Tighten bolts and nuts to specification. See TORQUE SPECIFICATIONS
(MONTERO & PICKUP) table at end of article.
Removal (3000GT)
1) Remove turbocharger(s) (if equipped). See TURBOCHARGER
under REMOVAL & INSTALLATION. On front manifold, remove serpentine
drive belt and alternator. Remove oil dipstick. On rear manifold,
remove EGR pipe (if equipped).
NOTE: Note locations and direction of installation of exhaust
manifold plain and spring washers for reinstallation
reference. DO NOT mix these fasteners.
2) On all manifolds, remove exhaust pipe-to-manifold nuts.
Lower exhaust pipe, and remove gasket. Remove heat protector. Remove
exhaust manifold nuts and washers. Note locations and direction of
installation of plain and spring washers for reinstallation reference.
DO NOT mix these fasteners. Remove exhaust manifold and gasket.
Inspection (3000GT)
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).
Installation (3000GT)
To install, reverse removal procedure using new gaskets.
Install new "O" ring on dipstick guide. Coat "O" ring with oil before
installation. Install manifold nuts and washers in original locations.
Tighten nuts to specification in sequence. See Fig. 4. See TORQUE
SPECIFICATIONS (3000GT) table at end of article.
Fig. 4: Exhaust Manifold Tightening Sequence (3000GT)
Courtesy of Mitsubishi Motor Sales of America, Inc.
CYLINDER HEADS

actuator (if equipped). Remove all drive belts. Remove alternator.
Remove drive belt tensioner assembly.
2) Using Holder (MB990767) and Adapter Bolts (MD998754),
remove crankshaft pulley. See Fig. 12. Disconnect brake fluid level
sensor. Remove upper timing belt covers. Support engine. Remove front
engine mount through bolt and front engine mount.
NOTE: Apply spray lubricant on reamer bolt during removal as bolt
is sometimes seized in engine support bracket.
Fig. 12: Exploded View of Timing Belt Components (DOHC)
Courtesy of Mitsubishi Motor Sales of America, Inc.
3) Remove drive belt idler pulley. Remove engine support
bracket bolts in proper sequence. See Fig. 10. Remove engine support

ALTE R NATO R & R EG ULA TO R

1991 M it s u bis h i M onte ro
1991 ELECTRICAL
Alternators & Regulators
Colt, Colt Vista, Colt 200, Ram-50, Stealth, Summit;
Eclipse, Galant, Mirage, Montero, Pickup, Precis, 3000GT
DESCRIPTION
Mitsubishi alternators are conventional 3-phase, self-
rectifying type units containing 6 diodes (3 positive and 3 negative)
which are used to rectify current. All models use a case-mounted
Integrated Circuit (IC) voltage regulator.
Alternator relay or resistor with diode is used to ensure
charging of battery even if charging indicator light is defective. See
Figs. 1 -9.
Fig. 1: Charging System Wiring Schematic (Colt, Mirage & Summit)
Courtesy of Mitsubishi Motor Sales of America.

BELT ADJUSTMENT TABLE








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Application ( 1) New Belt Deflection: In. (mm)
Colt, Colt 200 & Summit ..................... .28-.35 (7.1-8.9)
Mirage
1.5L ...................................... .28-.35 (7.1-8.9)
1.6L ..................................... .35-.45 (8.9-11.4)
Colt Vista .................................. .28-.34 (7.1-8.6)
Eclipse & Galant
1.8L ..................................... .32-.43 (8.1-10.9)
2.0L ..................................... .35-.45 (8.9-11.4)
Montero ..................................... .22-.32 (5.6-8.1)
Pickup & Ram-50
2.4L ...................................... .28-.39 (7.1-9.9)
3.0L ...................................... .32-.39 (8.1-9.9)
Precis ...................................... .28-.32 (7.1-8.1)
Stealth & 3000GT
DOHC ...................................... .16-.22 (4.1-5.6)
SOHC ...................................... .24-.35 (6.1-8.9)
( 1) - Deflection measured with 22 lbs. (10 kg) pressure applied midway
on belt run.









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TROUBLE SHOOTING
NOTE: See TROUBLE SHOOTING - BASIC PROCEDURES article in the
GENERAL INFORMATION section.
TESTING (ON-VEHICLE)
ALTERNATOR TO BATTERY CONTINUITY TEST
NOTE: Check alternator wire harness connections and drive belt
tension and ensure battery is fully charged before
performing test.
1) Turn ignition switch to OFF position. Disconnect negative
battery cable. Remove output lead from alternator terminal "B". See
Fig. 10 . Install a 100-amp ammeter in series to terminal "B" and
disconnected output lead. Install positive lead of ammeter to terminal
"B" and negative lead to disconnected output wire.
Fig. 10: Identifying Alternator Terminals
Courtesy of Chrysler Motors.
2) Install a digital voltmeter between alternator terminal
"B" and positive battery terminal. Install positive voltmeter lead to

terminal "B" and negative lead to positive battery terminal. Reconnect
negative battery cable.
3) Start engine. Turn accessories on and adjust engine speed
until ammeter indicates 20 amps, and note voltmeter reading. If
voltmeter indicates .2 volt or less, system is okay.
4) If voltage is greater than .2 volt, wiring is defective
between alternator terminal "B", fusible link and battery positive
terminal. Disconnect negative battery cable, and remove test
equipment.
ALTERNATOR OUTPUT TEST
NOTE: During alternator output test, a slightly discharged battery
should be used as a fully charged battery may not allow full
alternator output.
1) Turn ignition switch to OFF position. Disconnect negative
battery cable. Disconnect alternator output wire from terminal "B".
Install positive lead of 100-amp ammeter to terminal "B" and negative
lead to disconnected output lead.
CAUTION: Tighten each connection securely as heavy current flow will
exist. DO NOT use clips on ammeter.
2) Connect positive voltmeter lead (0-20 volts) to alternato\
r
terminal "B" and negative lead to ground. Install tachometer, and
reconnect negative battery cable.
3) Ensure voltmeter indicates battery voltage. If no voltage
exists, an open circuit is present in wire between alternator terminal
"B" and battery negative terminal. Check grounds and fusible link.
4) Turn headlights on, and start engine. Set headlights at
high beam and heater switch on HIGH. Quickly accelerate engine speed
to 2500 RPM and note alternator output current registered on the
ammeter. Minimum output should be within specification. Refer to the
ALTERNATOR MINIMUM OUTPUT SPECIFICATIONS table.
NOTE: Output voltage changes with electrical load and temperature.
Ensure proper electrical load is applied while checking
output. Nominal output may not be obtained if alternator or
ambient temperature is excessive. Allow to cool, and recheck
output. Alternator output is stamped on metal plate attached
to alternator case.
5) If minimum output is not obtained and alternator wiring is
okay, repair alternator. Disconnect negative battery cable, and remove
test equipment.
REGULATED VOLTAGE TEST
NOTE: Ensure battery is fully charged and proper drive belt
tension exists.
1) Turn ignition switch to OFF position. Disconnect negative
battery cable. Install a digital voltmeter between alternator terminal
"S" and ground. See Fig. 10. Connect positive voltmeter lead to
terminal "S" of alternator. Connect negative voltmeter lead to ground.
2) Disconnect alternator output wire from terminal "B".
Install a 100-amp ammeter in series to terminal "B" and disconnected
output lead. Install positive lead of ammeter to terminal "B" and
negative lead to disconnected output wire. Install a tachometer, and
reconnect negative battery cable.
3) Turn ignition switch to ON position and ensure voltmeter
indicates battery voltage. If no voltage exists, an open circuit

exists in wire between alternator terminal "S" and positive battery
terminal or fusible link is blown.
4) Start engine. Ensure all lights and accessories are off.
Operate engine at 2500 RPM and read voltmeter when alternator output
current drops to 10 amps or less. Voltage regulator is okay if voltage
output is within specification. See REGULATOR VOLTAGE SPECIFICATIONS
table.
BENCH TESTING
RECTIFIER ASSEMBLY
1) Using ohmmeter, check for continuity between both diodes
and stator coil lead connection. See Fig. 11. Reverse leads. If
continuity exists in both directions, diode is shorted. Replace
rectifier assembly.
2) To check entire diode assembly, use an ohmmeter to check
for continuity between both ends of each diode. See Fig. 11. Switch
ohmmeter leads. Continuity should exist in one direction, but not
other. If no continuity exists or continuity exists in both
directions, diode is defective. Replace rectifier assembly.
Fig. 11: Testing Rectifier Assembly
Courtesy of Mitsubishi Motor Sales of America.
ROTOR

1) Check continuity across rotor slip rings. Resistance
should be within specification. See ROTOR RESISTANCE SPECIFICATIONS
table. Replace rotor if no continuity exists or resistance is not
within specification.
2) Check continuity between individual slip rings and rotor
shaft. If continuity exists, rotor coil or slip ring is grounded.
Replace rotor.
STATOR
Ensure no continuity exists between stator coil leads and
stator core. Check continuity between leads of stator coil. If no
continuity exists between coil leads, replace stator.
OVERHAUL
Replace brushes if worn to limit line. Limit line is line
closest to rotor contact end of brush. Brushes can be retained in
brush holder while installing rotor by inserting wire into back of
rear housing.
Fig. 12: Exploded View of Typical Mitsubishi Alternator
Courtesy of Mitsubishi Motor Sales of America.
SPECIFICATIONS
ALTERNATOR MINIMUM OUTPUT SPECIFICATIONS TABLE








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Application Amps