1991 MITSUBISHI MONTERO fuel cap

.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

\003
F - B ASIC T E STIN G

1991 M it s u bis h i M onte ro
1991 ENGINE PERFORMANCE
Basic Diagnostic Procedures
Chrysler; Colt, Colt 200, Colt Vista, Ram-50, Stealth,
Summit
Mitsubishi; Eclipse, Galant, Mirage, Montero, Pickup, 3000GT
INTRODUCTION
The following diagnostic steps will help prevent overlooking
a simple problem. This is also where to begin diagnosis for a no start
condition. First step in diagnosing any driveability problem is
verifying customer's complaint with a test drive under conditions
problem reportedly occurred.
Before entering self-diagnostics, perform a careful and
complete visual inspection. Most engine control problems result from
mechanical breakdowns, poor electrical connections or
damaged/misrouted vacuum hoses. Before condemning computerized system,
perform each test listed in article.
NOTE: Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM)\
with a minimum 10-megohm input impedance, unless stated
otherwise in test procedure.
PRELIMINARY INSPECTION & ADJUSTMENTS
VISUAL INSPECTION
Visually inspect all electrical wiring, looking for chafed,
stretched, cut or pinched wiring. Ensure electrical connectors fit
tightly and are not corroded. Ensure distributor cap and rotor are
free of cracks, carbon trails or contamination. Ensure vacuum hoses
are properly routed and not pinched or cut. See M - VACUUM DIAGRAMS
article in the ENGINE PERFORMANCE Section to verify routing and
connections (if necessary). Inspect air induction system for possible
vacuum leaks.
MECHANICAL INSPECTION
Compression
Check engine mechanical condition with a compression gauge,
vacuum gauge, or an engine analyzer. See engine analyzer manual for
specific instructions.
WARNING: DO NOT use ignition switch during compression tests. Use a
remote starter to crank engine. Fuel injectors on many models
are triggered by ignition switch during cranking mode, which
can create a fire hazard or contaminate engine's oiling
system.
COMPRESSION SPECIFICATIONS TABLE (1)









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Application Specification
psi (kg/cm)
1.5L (VIN X) .............................. 137 (9.6)
1.6L (VIN Y) ............................. 171 (12.0)
1.8L (VIN T) .............................. 131 (9.2)

Fig. 3: Typical Thermostatic Air Cleaner System
FUEL EVAPORATIVE SYSTEM (EVAP)
The EVAP system allows for proper fuel system ventilation
while preventing fuel vapors from reaching the atmosphere. This means
that vapors must be caught and stored while the engine is off, which
is when most fuel evaporation occurs. When the engine is started,
these fuel vapors can be removed from storage and burned. In most
systems, storage is provided by an activated charcoal (or carbon)
canister. See Fig. 4. On a few early systems, charcoal canisters are
not used. Instead, fuel vapors are vented into the PCV system and
stored inside the crankcase.
The main components of a fuel evaporation system are a sealed
fuel tank, a liquid-vapor separator and vent lines to a vapor-storing
canister filled with activated charcoal. The filler cap is normally
not vented to the atmosphere, but is fitted with a valve to allow both
pressure and vacuum relief.
Although a few variations do exist between manufacturers,
basic operation is the same for all systems. Check for presence of
vapor storage canister or crankcase storage connections when required.
Ensure required hoses, solenoids, etc., are present and connected
properly. Check for proper type fuel tank cap. Check for any non-OEM
or auxiliary fuel tanks for compliance and the required number of
evaporation canisters.

CLUTCH PEDAL POSITION SWITCHES
COLD START INJECTORS
CONNECTORS
COOLANT
COOLANT RECOVERY TANKS
COOLING FAN MOTOR MODULES
COOLING FAN MOTOR RELAYS AND MODULES
COOLING FAN MOTOR RESISTORS
COOLING FAN MOTOR SENSORS AND SWITCHES
COOLING FAN MOTOR SWITCHES
COOLING FAN MOTORS
CRANKSHAFT POSITION SENSORS
DECEL VALVES
DEFLECTORS
DIP STICKS AND TUBES
DIP STICK TUBES
DISTRIBUTOR ADVANCES AND RETARDERS (MECHANICAL AND VACUUM)
DISTRIBUTOR BOOTS AND SHIELDS
DISTRIBUTOR CAPS
DISTRIBUTOR RETARDERS (MECHANICAL AND VACUUM)
DISTRIBUTOR ROTORS
DISTRIBUTOR SHIELDS
DISTRIBUTORS
EARLY FUEL EVAPORATION VALVES (HEAT RISER ASSEMBLIES)
EGR COOLERS
EGR EXHAUST MANIFOLD PASSAGES
EGR INTAKE AND EXHAUST MANIFOLD PASSAGES
EGR PLATES AND COOLERS
ELECTRONIC SPARK CONTROL MODULES
ELECTRONIC TRANSMISSION CONTROL DEVICES
ELECTRONIC TRANSMISSION FEEDBACK DEVICES
ENGINE COOLANT TEMPERATURE SENSORS
ENGINE COOLING SYSTEMS
ENGINE COVERS (OIL PAN, VALVE COVER, TIMING COVER)
ENGINE OIL
ENGINE OIL CANISTERS
ENGINE OIL COOLERS (EXTERNAL)
ENGINE OIL DRAIN PLUGS AND GASKETS
ENGINE OIL FILTERS AND CANISTERS
ENGINE OIL GASKETS
ENGINE OIL PRESSURE GAUGES (MECHANICAL)
EVAPORATIVE EMISSION (EVAP) CANISTER FILTERS
EVAPORATIVE EMISSION (EVAP) CANISTER PURGE DEVICES
EVAPORATIVE EMISSION (EVAP) CANISTERS
EVAPORATIVE EMISSION (EVAP) FEEDBACK DEVICES
EXHAUST GAS RECIRCULATION DEVICES
EXHAUST GAS RECIRCULATION FEEDBACK DEVICES
EXPANSION PLUGS
FAN CONTROL SENSORS
FUEL
FUEL ACCUMULATORS AND DAMPERS
FUEL AND COLD START INJECTORS
FUEL DAMPERS
FUEL DELIVERY CHECK VALVES
FUEL DISTRIBUTORS (BOSCH CIS)
FUEL FILLER NECKS AND RESTRICTORS
FUEL FILTERS
FUEL INJECTORS
FUEL LEVEL SENDERS7
FUEL PRESSURE REGULATORS
FUEL PUMPS (IN-TANK AND EXTERNAL, ELECTRICAL OR MECHANICAL)
FUEL RAILS
FUEL RESTRICTORS

FUEL TANKS
GAS CAPS
GASKETS
GROMMETS (VALVE COVER)
HARMONIC DAMPERS
HEATER CONTROL VALVES
HEATER CORES
HOSE AND TUBE COUPLERS, CONNECTORS AND CLAMPS
HOSE CLAMPS
HOSE CONNECTORS
HOSE COUPLERS
HOSES AND TUBES (FUEL LINES, RADIATOR, VACUUM, BY PASS,
HEATER, RECOVERY TANK AND OIL COOLERS)
HOUSINGS
IDLE AIR CONTROLS
IDLE SPEED CONTROL ACTUATORS
IGNITION BOOTS
IGNITION COIL TOWERS
IGNITION COILS
IGNITION CONTROL MODULES (ICM)
IGNITION SWITCHES
IGNITION TERMINALS
IGNITION WIRES, BOOTS, COIL TOWERS AND TERMINALS (SECONDARY)
IN-TANK FUEL STRAINERS
INERTIA FUEL SHUT-OFF SWITCHES
INTAKE AIR TEMPERATURE SENSORS
INTAKE MANIFOLDS
INTERCOOLERS
KNOCK SENSORS
LIQUID VAPOR SEPARATORS
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSORS
MASS AIR FLOW (MAF) SENSORS
METAL AIR MANIFOLDS AND PIPES
METAL AIR PIPES
MIX CONTROL SOLENOIDS
MOTOR MOUNTS
O-RINGS, GASKETS, SEALS AND SPRING LOCKS
O2 SENSORS
OIL PRESSURE SENDING UNITS
OIL PUMP PICK-UP SCREENS
OIL PUMPS
PARK NEUTRAL POSITION SWITCHES
PCV BREATHER ELEMENTS
PCV ORIFICES
PCV VALVES
PICK-UP ASSEMBLIES (INCLUDES MAGNETIC, HALL EFFECT AND
OPTICAL)
POWER STEERING PRESSURE SENSORS
POWERTRAIN CONTROL MODULES (PCM) AND PROM
POWERTRAIN CONTROL PROM
PRESSURIZED EXPANSION TANK CAPS
RADIATOR CAPS AND PRESSURIZED EXPANSION TANK CAPS
RADIATOR FAN BLADES
RADIATOR FAN CLUTCHES
RADIATORS
ROLL OVER VALVES
SEALING COMPOUNDS
SEALS
SECONDARY AIR INJECTION SYSTEM MANAGEMENT DEVICES
SENSORS AND ACTUATORS
SHROUDS, BAFFLES AND DEFLECTORS
SPARK PLUGS
SPRING LOCKS

FUEL RAILS
FUEL RAIL INSPECTION








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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Contaminated ............ A ........ ( 1) Require replacement.
Leaking ................. A .. Require repair or replacement.
Restricted .............. A .. Require repair or replacement.
Rust-pitted ............. 1 ............ Suggest replacement.
( 1) - Determine source of contamination. Require repair or
replacement.









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FUEL RESTRICTORS
See FUEL FILLER NECKS AND RESTRICTORS .
FUEL TANKS
FUEL TANK INSPECTION








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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Baffles loose ........... A .. Require repair or replacement.
Contaminated ............ A ............. ( 1) Require repair.
Corroded internally ..... A .. Require repair or replacement.
Distorted, affecting
performance ............ B ............ Require replacement.
Distorted, not affecting
performance ............ .. ........ No service suggested or
required.
Leaking ................. A .. Require repair or replacement.
( 1) - Determine source of contamination. Require repair or
replacement.









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GAS CAPS
GAS CAP INSPECTION








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Terminal burned, affecting
performance ............ A ........... (2) 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.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead corroded ...... A .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
( 1) - Refer to manufacturer's diagnostic trouble code
procedure and require repair or replacement of affected
component(s).
( 2) - Determine cause and correct prior to repair or
replacement of part.
( 3) - Determine source of contamination, such as engine coolant,
fuel, metal particles, or water. Require repair or
replacement.
( 4) - Includes inoperative, intermittent operation, failure to
perform all functions, or out of OEM specification.









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POWERTRAIN CONTROL PROM
See POWERTRAIN CONTROL MODULES (PCM) AND PROM .
PRESSURIZED EXPANSION TANK CAPS
See RADIATOR CAPS AND PRESSURIZED EXPANSION TANK CAPS .
RADIATOR CAPS AND PRESSURIZED EXPANSION TANK CAPS
RADIATOR CAP AND PRESSURIZED EXPANSION TANK CAP INSPECTION








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Condition Code Procedure
Application incorrect ... B ........... Require replacement.
Coolant recovery check
valve inoperative ...... A ....... ( 1) Require replacement.
Fails to maintain proper
pressure ............... B ........... Require replacement.
Gasket missing .......... C . Require replacement of gasket.
Missing ................. C ........... Require replacement.
Seal missing ............ C ... Require replacement of seal.
( 1) - Inoperative includes intermittent operation or out of
OEM specification.









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RADIATOR FAN BLADES

CATALYTIC CONVERTER
Continued operation of vehicle with a severe malfunction
could cause converter to overheat, resulting in possible damage to
converter and vehicle.
COOLANT (PROPYLENE-GLYCOL FORMULATIONS)
CAUTION: To avoid possible damage to vehicle use only ethylene-glycol
based coolants with a mixture ratio from 44-68% anti-freeze.
DO NOT use 100% anti-freeze as it will cause the formation
of cooling system deposits. This results in coolant
temperatures of over 300
\b F (149\bC) which can melt plastics.
100% anti-freeze has a freeze point of only -8\b F (-22\bC).
CAUTION: Propylene-Glycol Mixtures has a smaller temperature range
than Ethylene-Glycol. The temperature range (freeze-boil)
of a 50/50 Anti-Freeze/Water Mix is as follows:
Propylene-Glycol -26
\b F (-32\bC) - 257\b F (125\bC)
Ethylene-Glycol -35\b F (-37\bC) - 263\b F (128\bC)
CAUTION: Propylene-Glycol/Ethylene-Glycol Mixtures can cause the
destabilization of various corrosion inhibitors. Also
Propylene-Glycol/Ethylene-Glycol has a different specific
gravity than Ethylene-Glycol coolant, which will result in
inaccurate freeze point calculations.
ELECTROSTATIC DISCHARGE SENSITIVE (ESD) PARTS
WARNING: Many solid state electrical components can be damaged by
static electricity (ESD). Some will display a warning label,
but many will not. Discharge personal static electricity by
touching a metal ground point on the vehicle prior to
servicing any ESD sensitive component.
ENGINE OIL
CAUTION: Never use non-detergent or straight mineral oil.
FUEL SYSTEM SERVICE
WARNING: Relieve fuel system pressure prior to servicing any fuel
system component (fuel injection models).
HALOGEN BULBS
WARNING: Halogen bulbs contain pressurized gas which may explode if
overheated. DO NOT touch glass portion of bulb with bare
hands. Eye protection should be worn when handling or working
around halogen bulbs.
RADIATOR CAP
CAUTION: Always disconnect the fan motor when working near the
radiator fan. The fan is temperature controlled and could
start at any time even when the ignition key is in the OFF
position. DO NOT loosen or remove radiator cap when cooling
system is hot.
RADIATOR FAN