1991 MITSUBISHI MONTERO gas type

NOTE: Always refer to appropriate engine overhaul article in the
ENGINES section for complete overhaul procedures and
specifications for the vehicle being repaired.
REMOVAL
Remove intake and exhaust manifolds and valve cover. Cylinder
head and camshaft carrier bolts (if equipped), should be removed only
when the engine is cold. On many aluminum cylinder heads, removal
while hot will cause cylinder head warpage. Mark rocker arm or
overhead cam components for location.
Remove rocker arm components or overhead cam components.
Components must be installed in original location. Individual design
rocker arms may utilize shafts, ball-type pedestal mounts or no rocker
arms. For all design types, wire components together and identify
according to the corresponding valve. Remove cylinder head bolts.
Note length and location. Some applications require cylinder head
bolts be removed in proper sequence to prevent cylinder head damage.
See Fig. 1 . Remove cylinder head.
Fig. 1: Typical Cylinder Head Tightening or Loosening Sequence
This Graphic For General Information Only
INSTALLATION
Ensure all surfaces and head bolts are clean. Check that head
bolt holes of cylinder block are clean and dry to prevent block damage
when bolts are tightened. Clean threads with tap to ensure accurate
bolt torque.
Install head gasket on cylinder block. Some manufacturer's
may recommend sealant be applied to head gasket prior to installation.
Note that all holes are aligned. Some gasket applications may be
marked so certain area faces upward. Install cylinder head using care
not to damage head gasket. Ensure cylinder head is fully seated on
cylinder block.
Some applications require head bolts be coated with sealant
prior to installation. This is done if head bolts are exposed to water
passages. Some applications require head bolts be coated with light
coat of engine oil.

Reasons to Suggest Repair or Replacement
1 - Part is close to the end of its useful life (just above
discard specifications, or weak; failure likely to occur
soon, etc.)
2 - To address a customer need, convenience, or request (to
stiffen ride, enhance performance, eliminate noise,
etc.)
3 - To comply with maintenance recommended by the vehicle's
Original Equipment Manufacturer (OEM)
4 - Technician's recommendation based on substantial and
informed experience
NOTE: Suggested services are always optional. When presenting
suggested repairs to the customer, you must present the
facts, allowing the customer to draw their own conclusions
and make an informed decision about how to proceed.
ENGINE ASSEMBLIES
SERVICE PROCEDURES REQUIRED AND SUGGESTED FOR PROPER VEHICLE
OPERATION
CYLINDER HEAD ASSEMBLIES
NOTE: A Cylinder Head Assembly is a cylinder head fitted with
valves, associated springs, retainers, and on overhead
camshaft cylinder heads (OHC), camshaft, camshaft
bearings, lash adjusters, tappets and rockers.
CYLINDER HEAD ASSEMBLY INSPECTION









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Condition Code Procedure
Adjustable valve lash is
out of specification ... B ................. Require repair.
Internal component failure
(any component) ........ A ........... ( 1) Require repair or
replacement of cylinder
head assembly.
( 1) - It is Required that all other failure related components
be inspected for cause and condition. Additional components
or assemblies may be Suggested for repair or replacement,
such as a water pump on a short block (reason code 4,
technician's recommendation based on substantial and
informed experience).
Example:
If there is a failed head gasket with an external coolant
leak, in addition to Requiring replacement of the head
gasket, inspection of the following for cause and condition
is Required: Block, Cooling System, Cylinder Head. It may
be Suggested that additional inspections be performed, such
as the other head gasket on a V-type engine.









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LONG BLOCK ASSEMBLIES
NOTE: A Long Block Assembly is a short block assembly together
with a cylinder head assembly and all those components
fitted within the rocker or cam cover, and timing cover

(the whole presented as an assembly). A rebuilt or new
oil pump, or kit shall be supplied or fitted as
appropriate.
LONG BLOCK ASSEMBLY INSPECTION









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Condition Code Procedure
Internal component failure
(any component) ........ A ........... (1) Require repair or
replacement of the long
block assembly.
( 1) - It is Required that all other failure related components
be inspected for cause and condition. Additional components
or assemblies may be Suggested for repair or replacement
such as a water pump on a short block (reason code 4,
technician's recommendation based on substantial and
informed experience).
Example:
If there is a failed head gasket with an external coolant
leak, in addition to Requiring replacement of the head
gasket, inspection of the following for cause and
condition is Required: Block, Cooling System, Cylinder
Head. It may be Suggested that additional inspections be
performed, such as the other head gasket on a V-type
engine.









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SHORT BLOCK ASSEMBLIES
NOTE: A Short Block Assembly is a cylinder block and all those
components contained within the limits of the block deck
or decks, the pan rail, the block rear face and the
timing cover (where fitted), including the crankshaft.
SHORT BLOCK ASSEMBLY INSPECTION









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Condition Code Procedure
Any internal component
failure ................ A ........... ( 1) Require repair or
replacement of the short
block assembly.
( 1) - It is Required that all other failure related components
be inspected for cause and condition. Additional
components or assemblies may be Suggested for repair or
replacement, such as a water pump on a short block
(reason code 4, technician's recommendation based on
substantial and informed experience).
Example:
If there is a failed head gasket with an external coolant
leak, in addition to Requiring replacement of the head
gasket, inspection of the following for cause and condition
is Required: Block, Cooling System, Cylinder Head. It may
be Suggested that additional inspections be performed,
such as the other head gasket on a V-type engine.









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Inoperative ............. B ........... (3) Require repair or
replacement. Further
inspection required.
Leaking ................. A .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Resistance out of
specification .......... B .. Require repair or replacement.
Restricted, affecting
performance ............ A .. Require repair or 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.
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) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Determine source of contamination, such as engine coolant,
fuel, metal particles, or water. Require repair or
replacement.
( 3) - Inoperative includes intermittent operation or out of
OEM specification. Some components may be serviceable;
check for accepted cleaning procedure.









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EXHAUST GAS RECIRCULATION DEVICES
EXHAUST GAS RECIRCULATION DEVICE INSPECTION








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Condition Code Procedure
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware
threads damaged ........ A ... Require repair or replacement
of hardware.
Attaching hardware
threads stripped
(threads missing) ...... A ... Require repair or replacement
of hardware.
Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking .......... A .. Require repair or replacement.
Connector melted ........ A ........... ( 1) Require repair or
replacement.

Condition Code Procedure
Application incorrect ... B ........... Require replacement.
Fails to maintain proper
pressure ............... A ........... Require replacement.
Gaskets missing ......... C ........... Require replacement.
Leaking ................. A ........... Require replacement.
Missing ................. C ........... Require replacement.
Plugged (vacuum and
pressure relief) ....... A ........... Require replacement.
Seals missing ........... C ........... Require replacement.









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GASKETS
GASKET INSPECTION








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Condition Code Procedure
Leaking ................. A ........... ( 1) Require repair or
replacement.
( 1) - Require inspection of mating and sealing surface and
repair or replace as necessary.









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GROMMETS (VALVE COVER)
GROMMET (VALVE COVER) INSPECTION








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Condition Code Procedure
Leaking ................. 2 ........... ( 1) Suggest repair or
replacement.
( 1) - Require inspection of mating and sealing surface and
repair or replace as necessary.









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HARMONIC DAMPERS
HARMONIC DAMPER INSPECTION








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Condition Code Procedure
Application incorrect ... B ........... Require replacement.
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.
Cracked ................. A ........... Require replacement.
Dented (fluid
type only) ............. A ........... Require replacement.
Keyway distorted ........ A . Require repair or replacement.
Leaking (Fluid damper
only) .................. A ........... Require replacement.
Loose ................... A ........... Require replacement.
Noisy ................... A ........... Require replacement.

loose .................. A ... Require repair or replacement
of injection tube or
replacement of catalytic
converter.
Air injection tube
restricted ............. A ... Require repair or replacement
of injection tube or
replacement of catalytic
converter.
Air injection tube
threads damaged ........ A ... Require repair or replacement
of injection tube or
replacement of catalytic
converter.
Air injection tube
threads stripped
(threads missing) ...... A ... Require repair or replacement
of injection tube or
replacement of catalytic
converter.
Body cracked ............ B .. Require repair or replacement.
Converter empty ......... A .. Require repair or replacement.
Converter fill plug
missing ................ C .. Require repair or replacement.
Converter missing ....... C ............ Require replacement.
Exhaust gases leaking ... A .. Require repair or replacement.
Flanges leaking ......... A ... Require repair or replacement
of flanges.
Inlet pipes cracked ..... B .. Require repair or replacement.
Internal rattle (except
pellet-type) ........... 2 .......... (1) Further inspection
required.
Mounting brackets that
are part of converter
broken ................. A .. Require repair or replacement.
Obvious overheating ..... .. ......... ( 2) Require testing of
converter.
Outlet pipes cracked .... B .. Require repair or replacement.
Pieces of catalyst
material found
downstream ............. 1 ............ Suggest replacement.
Plugged ................. A ........ ( 3) Require replacement.
Testing has determined
that existing converter
has been lead-poisoned,
contaminated, or failed
testing ................ A .. Require repair or replacement.
( 1) - If the converter is breaking up, suggest converter
replacement. If an object has fallen into the converter,
remove the object.
( 2) - Overheating is caused by something other than the
converter. Further diagnosis is required to determine
the cause of the overheating.
( 3) - Determine cause and correct to ensure that new converter
will not become plugged.









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EXHAUST AND TAIL PIPES
NOTE: For pipes with resonators, also see MUFFLERS AND RESONATORS.
EXHAUST AND TAIL PIPE INSPECTION

Installation
1) To install, reverse removal procedure. Injectors may be
removed after fuel rail is removed from intake manifold. Use new
insulators and "O" rings when installing injectors.
2) Use spindle oil or gasoline on "O" ring. Install injectors
into fuel rail with a twisting motion. Adjust throttle and kickdown
cable (if applicable). Do not drop injectors while removing or
installing fuel rail.
OXYGEN (O2) SENSOR
Removal & Installation
1) O2 Sensor is mounted in exhaust pipe below exhaust header.
It is equipped with a permanent pigtail which must be protected from
damage when sensor is removed. Ensure sensor is free of contaminants,
avoid using cleaning solvents of any type. Sensor may be difficult to
remove when engine temperature is less than 120
F (48 C).
2) Always use anti-seize compound on threads before
installation. On non-turbo models, remove sensor using Remover
(MD998703). On turbo models, use Remover (MD998748) on Eclipse and
Galant, or Remover (MD998770) on Stealth and 3000GT. Tighten oxygen
sensor to specification. See TORQUE SPECIFICATIONS table.
THROTTLE BODY
Removal
Disconnect air intake hose. Remove accelerator and automatic
speed control cables (if equipped). Disconnect fuel vapor hose,
electrical harness connector, vacuum hose and coolant hoses. Remove
throttle body retaining bolts.
Disassembly
Remove throttle position sensor. Remove idle speed control
motor. Remove throttle bracket and connector bracket (if equipped).
Remove idle position switch and adjusting nut.
NOTE: DO NOT remove throttle valve. DO NOT use cleaning solvents
on throttle position sensor, idle speed control motor or
idle position switch.
Cleaning
Clean all parts except those noted in solvent. Check vacuum
port and passage for clogging. Clean vacuum, vapor and fuel passages
with compressed air.
Reassembly
To reassemble, reverse disassembly procedure.
Installation
To install, reverse removal procedure.
THROTTLE POSITION SENSOR/SWITCH
Removal & Installation
Throttle position sensor/switch is located on throttle body.
Disconnect TPS electrical connector. Remove bolts holding TPS and
remove TPS. To install, reverse removal procedure. Tighten throttle
position sensor/switch to specification. See TORQUE SPECIFICATIONS
table. For adjustment procedure, see ON-VEHICLE ADJUSTMENTS article.
TURBOCHARGERS

Excessive cylinder wear Rebore or replace
block
Excessive valve guide Worn or loose bearing
clearance









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Gap Bridged Deposits in combustion Clean combustion
chamber becoming fused chamber of deposits
to electrode









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Blistered Engine overheating Check cooling system
Electrode
Wrong type of fuel Replace with correct
fuel
Loose spark plugs Retighten spark plugs
Over-advanced ignition Reset ignition timing
timing see ENGINE PERFORMANCE









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Pre-Ignition or Incorrect type of fuel Replace with correct
Melted Electrodes fuel
Incorrect ignition timing Reset ignition timing
see ENGINE PERFORMANCE
Burned valves Replace valves
Engine Overheating Check cooling system
Wrong type of spark plug, Replace with correct
too hot spark plug, see
ENGINE PERFORMANCE









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Chipped Severe detonation Check for over-
Insulators advanced timing or
combustion
Improper gapping Re-gap spark plugs
procedure









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Rust Colored Additives in unleaded Try different fuel
Deposits fuel brand









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Water In Combus- Blown head gasket or Repair or replace
tion Chamber cracked head head or head gasket









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NOTE: Before diagnosing an electronic ignition system, ensure that
all wiring is connected properly between distributor, wiring
connector and spark plugs. Ignition problem will show up
either as: Engine Will Not Start or Engine Runs Rough.
BASIC ELECTRONIC IGNITION TROUBLE SHOOTING CHARTS









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CONDITION POSSIBLE CAUSE CORRECTION








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Engine Won't Open circuit between Repair circuit
Start distributor and bulkhead
connector
Open circuit between Repair circuit
bulkhead connector and