1991 MITSUBISHI MONTERO engine
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![MITSUBISHI MONTERO 1991 Service Manual Vacuum leaks Repair vacuum leaks
Fuel lines clogged Remove restriction
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Fuel lines clogged Remove restriction
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Vacuum leaks Repair vacuum leaks
Fuel lines clogged Remove restriction
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Hesitation Cracked or broken vacuum Replace vacuum hoses
hoses
Vacuum leaks Repair Vacuum leaks
Binding carburetor linkage Eliminate binding
Binding throttle linkage Eliminate binding
Binding choke linkage or Eliminate binding
fast idle cam
Improper float setting Readjust float
setting, see FUEL
Cracked or broken ignition Replace ignition
wires wires
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Rough idle, Incorrect curb idle or fast Reset idle speed, see
Missing or idle speed see ENGINE PERFORMANCE
Stalling
Incorrect basic timing Reset ignition timing
see ENGINE PERFORMANCE
Improper idle mixture Reset idle mixture,
adjustment see ENGINE PERFORMANCE
Improper feedback system Check feedback system
operation see ENGINE PERFORMANCE
Incorrect spark plug gap Reset spark plug gap,
see ENGINE PERFORMANCE
Moisture in ignition Dry components
components
Loose or broken ignition Replace ignition
wires wires
Damaged distributor cap or Replace distributor
or rotor cap or rotor
Faulty ignition coil Replace ignition coil
Fuel filter clogged or worn Replace fuel filter
Damaged idle mixture screw Replace idle mixture
screw, see FUEL
Improper fast idle cam Reset fast idle cam
adjustment adjustment, see TUNE-
see ENGINE PERFORMANCE
Improper EGR valve operation Replace EGR valve
Faulty PCV valve air flow Replace PCV valve
Choke binding or improper Reset choke or
choke setting eliminate binding
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Vacuum leak Repair vacuum leak
Improper float bowl fuel Reset float
level adjustment, see FUEL
Clogged air bleed or idle Clean carburetor
passages passages, see FUEL
Clogged or worn air cleaner Replace air filter
filter
Faulty choke vacuum Replace diaphragm,
diaphragm see ENGINE PERFORMANCE
Exhaust manifold heat valve Replace heat valve
inoperative
Improper distributor spark Check distributor
advance operation
Leaking valves or valve Check and repair
components valvetrain
Improper carburetor Remove and remount
mounting carburetor
Excessive play in Replace distributor
distributor shaft
Loose or corroded wiring Repair or replace as
connections required
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Engine Surges Improper PCV valve airflow Replace PCV valve
Vacuum leaks Repair vacuum leaks
Clogged air bleeds Remove restriction
EGR valve malfunction Replace EGR valve
Restricted air cleaner Replace air filter
filter
Cracked or broken vacuum Replace vacuum hoses
hoses
Cracked or broken ignition Replace ignition
wires wires
Vacuum advance malfunction Check unit and
replace as necessary
Defective or fouled spark Replace spark plugs
plugs
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Ping or Spark Incorrect ignition timing Reset ignition timing
Knock see ENGINE PERFORMANCE
Distributor centrifugal or Check operation and
vacuum advance malfunction replace as necessary
Carburetor setting too lean Readjust mixture
Page 1230 of 1333
setting, see ENGINE
PERFORMANCE
Vacuum leak Eliminate vacuum leak
EGR valve malfunction Replace EGR valve
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Poor Gasoline Cracked or broken vacuum Replace vacuum hoses
Mileage hoses
Vacuum leaks Repair vacuum leaks
Defective ignition wires Replace wires
Incorrect choke setting Readjust setting, see
ENGINE PERFORMANCE
Defective vacuum advance Replace vacuum advance
Defective spark plugs Replace spark plugs
Binding carburetor power Eliminate binding
piston
Dirt in carburetor jets Clean and/or replace
jets
Incorrect float adjustment Readjust float
setting, see FUEL
Defective power valve Replace power valve,
see ENGINE PERFORMANCE
Incorrect idle speed Readjust idle speed
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Engine Stalls Improper float level Readjust float level
Leaking needle valve and Replace needle valve
seat and seat
Vacuum leaks Eliminate vacuum
leaks
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VACUUM PUMP - DIESEL TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
NOTE: Diesel engines mechanical diagnosis is the same as gasoline
engines for items such as noisy valves, bearings, pistons,
etc. The following trouble shooting covers only items
pertaining to diesel engines.
VACUUM PUMP (DIESEL) TROUBLE SHOOTING CHART
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CONDITION POSSIBLE CAUSE CORRECTION \
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Page 1231 of 1333
Excessive Noise Loose pump-to-drive Tighten screws
assembly screws
Loose tube on pump assembly Tighten tube
Valves not functioning Replace valves
properly
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Oil Leakage Loose end plug Tighten end plug
Bad seal crimp Remove and re-crimp
seal
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MANUAL TRANSMISSION
MANUAL TRANSMISSION TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
MANUAL TRANSMISSION/TRANSAXLE TROUBLE SHOOTING
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Condition Possible Cause \
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Noisy In Forward Gears .Low gear oil level,
.Loose bell housing bolts,
.Worn bearings or gears
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Clunk On Deceleration
(FWD Only) .Loose engine mounts,
.Worn inboard CV joints,
.Worn differential pinion shaft,
.Side gear hub counterbore
in case worn oversize
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Gear Clash When Shifting
Forward Gears .Clutch Out Of Adjustment,
.Shift linkage damaged or
out of adjustment,
.Gears or synchronizers damaged,
.Low gear oil level
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Transmission Noisy When
Moving (RWD Only) Quiet In
Neutral With Clutch Engaged .Worn rear outputshaft bearing
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Gear Rattle .Worn bearings,
.Wrong gear oil,
.Low gear oil,
.Worn gears
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Steady Ticking At Idle
(Increases With RPM) .Broken tooth on gear
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Gear Clash When Shifting
Forward Gears .Worn or broken synchronizers
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Loud Whine In Reverse .Normal condition ( 1) \
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Page 1232 of 1333
![MITSUBISHI MONTERO 1991 Service Manual Noise When Stepping On Clutch .Bad release bearing,
.Worn pilot bearing
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.Worn pilot bearing
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Noise When Stepping On Clutch .Bad release bearing,
.Worn pilot bearing
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Ticking Or Screeching As
Clutch Is Engaged .Faulty release bearing,
.Uneven pressure plate fingers
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Click Or Snap When Clutch
Is Engaged .Worn clutch fork,
.Worn or broken front bearing
retainer
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Transmission Shifts Hard .Clutch not releasing,
.Shift mechanism binding,
.Clutch installed backwards
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Will Not Shift Into One
Gear, Shifts Into All
Others .Bent shift fork,
.Worn detent balls
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Locked Into Gear,
Cannot Shift .Clutch adjustment,
.Worn detent balls
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Transmission Jumps Out
Of Gear .Pilot bearing worn,
.Bent shift fork,
.Worn gear teeth or face
.Excessive gear train end play
.Worn synchronizers
.Missing detent ball spring
.Shift mechanism worn or out of
adjustment
.Engine or transmission mount
bolts loose or out of adjustment
.Transmission not aligned
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Shift Lever Rattle .Worn shift lever or detents
.Worn shift forks
.Worn synchronizers sleeve
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Shift Lever Hops Under
Acceleration .Worn engine or transmission
mounts
( 1) - Most units use spur cut gears in reverse and are noisy
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POWERTRAIN
CLUTCH TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
BASIC CLUTCH TROUBLE SHOOTING CHART
Page 1233 of 1333
![MITSUBISHI MONTERO 1991 Service Manual \
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CONDITION POSSIBLE CAUSE](/manual-img/19/57332/w960_57332-1232.png "MITSUBISHI MONTERO 1991 Service Manual \
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CONDITION POSSIBLE CAUSE")
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CONDITION POSSIBLE CAUSE CORRECTION \
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Chattering or Incorrect clutch adjustment Adjust clutch
Grabbing
Oil, grease or glaze on Disassemble and clean
facings or replace
Loose "U" joint flange See DRIVE AXLES
article
Worn input shaft spline Replace input shaft
Binding pressure plate Replace pressure plate
Binding release lever See CLUTCH article
Binding clutch disc hub Replace clutch disc
Unequal pressure plate Replace worn/misaligned
contact components
Loose/bent clutch disc Replace clutch disc
Incorrect transmission Realign transmission
alignment
Worn pressure plate, disc Replace damaged
or flywheel components
Broken or weak pressure Replace pressure
springs plate
Sticking clutch pedal Lubricate clutch pedal
& linkage
Incorrect clutch disc Replace clutch disc
facing
Engine loose in chassis Tighten all mounting
bolts
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Failure to Oil or grease on clutch Clean or replace clutch
Release facings clutch disc
Incorrect release lever or See CLUTCH article
pedal adjustment
Worn or broken clutch Replace clutch disc
facings
Bent clutch disc or Replace damaged
pressure plate components
Clutch disc hub binding on Clean or replace clutch
input shaft disc and/or input shaft
Binding pilot bearing Replace pilot bearing
Sticking release bearing Replace release bearing
sleeve and/or sleeve
Binding clutch cable See CLUTCH article
Page 1235 of 1333
Dry or binding clutch Lubricate and align
pedal hub components
Floor mat interference Lay mat flat in proper
with pedal area
Dry or binding ball/fork Lubricate and align
pivots components
Faulty clutch cable Replace clutch cable
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Noisy Clutch Faulty interlock switch Replace interlock
Pedal switch
Self-adjuster ratchet Lubricate or replace
noise self-adjuster
Speed control interlock Lubricate or replace
switch interlock switch
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Clutch Pedal Binding clutch cable See CLUTCH article
Sticks Down
Springs weak in pressure Replace pressure plate
plate
Binding in clutch linkage Lubricate and free
linkage
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Noisy Dry release bearing Lubricate or replace
release bearing
Dry or worn pilot bearing Lubricate or replace
bearing
Worn input shaft bearing Replace bearing
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Transmission Weak springs in pressure Replace pressure plate
Click plate
Release fork loose on ball Replace release fork
stud and/or ball stud
Oil on clutch disc damper Replace clutch disc
Broken spring in slave Replace slave cylinder
cylinder
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DRIVE AXLE - NOISE DIAGNOSIS
Unrelated Noises
Some driveline trouble symptoms are also common to the
engine, transmission, wheel bearings, tires, and other parts of the
vehicle. Ensure cause of trouble actually is in the drive axle before
adjusting, repairing, or replacing any of its parts.
Non-Drive Axle Noises
A few conditions can sound just like drive axle noise and
have to be considered in pre-diagnosis. The 4 most common noises are
exhaust, tires, CV/universal joints and wheel trim rings.
Page 1237 of 1333
axle backlash. If backlash is one inch or less, drive axle is not the
source of clunk noise.
Bearing Whine
Bearing whine is a high-pitched sound similar to a whistle.
It is usually caused by malfunctioning pinion bearings. Pinion
bearings operate at drive shaft speed. Roller wheel bearings may whine
in a similar manner if they run completely dry of lubricant. Bearing
noise will occur at all driving speeds. This distinguishes it from
gear whine, which usually comes and goes as speed changes.
Bearing Rumble
Bearing rumble sounds like marbles being tumbled. It is
usually caused by a malfunctioning wheel bearing. The lower pitch is
because the wheel bearing turns at only about 1/3 of drive shaft
speed.
Chatter On Turns
This is a condition where the entire front or rear of vehicle
vibrates when vehicle is moving. The vibration is plainly felt as well
as heard. Extra differential thrust washers installed during axle
repair can cause a condition of partial lock-up that creates this
chatter.
Axle Shaft Noise
Axle shaft noise is similar to gear noise and pinion bearing
whine. Axle shaft bearing noise will normally distinguish itself from
gear noise by occurring in all driving modes (Drive, cruise, coast and
float), and will persist with transmission in Neutral while vehicle is
moving at problem speed.
If vehicle displays this noise condition, remove suspect
axle shafts, replace wheel seals and install a new set of bearings.
Re-evaluate vehicle for noise before removing any internal components.
Vibration
Vibration is a high-frequency trembling, shaking or grinding
condition (felt or heard) that may be constant or variable in level
and can occur during the total operating speed range of the vehicle.
The types of vibrations that can be felt in the vehicle can
be divided into 3 main groups:
* Vibrations of various unbalanced rotating parts of the
vehicle.
* Resonance vibrations of the body and frame structures caused
by rotating of unbalanced parts.
* Tip-in moans of resonance vibrations from stressed engine or
exhaust system mounts or driveline flexing modes.
DRIVE AXLE - RWD TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing. For definitions
of listed noises or sounds, see DRIVE AXLE - NOISE DIAGNOSIS
under POWERTRAIN.
DRIVE AXLE (RWD) TROUBLE SHOOTING
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CONDITION POSSIBLE CAUSE CORRECTION