tire type ISUZU TROOPER 1995 Workshop Manual

OB-4 MAINTENANCE AND LUBRICATION
EXPLANATION OF COMPLETE VEHICLE
MAINTENANCE
SCHEDULE
Brief explanations of the services listed in the
preceeding Maintenance Scheduled are presented
below.
Replace
all questionable parts and note any necessary
repairs
as you perform these maintenance
procedures.
FRONT AND REAR AXLE LUBRICANT
REPLACEMENT
Check the lubricant level after every 7,500 miles
(12,000 km) of operation and add lubricant to level
of filler hole if necessary.
Replace the front and rear
axle lubricant at 15,000
miles (24,000 km) and 30,000 miles (48,000 km) and
after every 30,000
miles (48,000 km) or operation
thereafter.
MANUAL TRANSMISSION LUBRICANT
REPLACEMENT
Check the lubricant level after every 7,500 miles
(12,000 km) of operation and add lubricant to level
of filler hole if necessary.
Replace the transmission
lubricant at 15,000 miles
(24,000 km) and 30,000 miles (48,000 km) and after
every 30,000
miles (48,000 km) of operation there­
after.
TRANSFER CASE LUBRICANT
REPLACEMENT
Check the lubricant level after every 7,500 miles
(12,000 km) of operation and add lubricant to level
of filler hole if necessary.
Replace
the transfer case lubricant at 15,000 miles
(24,000 km) and 30,000 miles (48,000 km) and after
every 30,000
miles (48,000 km) of operation there­
after.
AIR CLEANER ELEMENT REPLACEMENT
Replace the air cleaner under normal operating
conditions every 30,000 miles (48,000 km).
Operation
of the vehicle in dusty areas will
necessitate more frequent replacement.
SPARK PLUG REPLACEMENT
Replace the plugs at 30,000 mile (48,000 km) intervals
with the type specified at the end of this section.
COOLING SYSTEM SERVICE
Drain, flush and refill system with new engine coolant.
Refer
to "Recommended Fluids and Lubricants" in
this section,
or ENGINE COOLING (SEC. 68).
TIMING BELT REPLACEMENT
Replacement of the timing belt is recommended at
every 60,000 miles (96,000 km).
Failure
to replace the timing belt may result in serious
damage
to the engine.
TIRE ROTATION
Rotate tires every 7,500 miles (12,000 km).
POWER STEERING FLUID REPLACEMENT
Drain the power steering fluid and then refill the
system
to the proper level with power steering fluid
after every 30,000 miles (48,000 km) of operation.
See the appropriate section
of this manual for further
details.
FRONT WHEEL HUBS LUBRICANT
REPLACEMENT
Clean and repack the front wheel bearings at 30,000
mile (48,000 km) intervals.
Clean and lubricate the free wheeling hubs at the
same
time the front wheel bearings are serviced.
Refer
to FRONT DRIVING AXLE (SEC. 4C).
RADIATOR CORE AND AIR CONDITIONING
CONDENSER CLEANING
Clean the front of the radiator core and air con­
ditioning condenser, at 60,000 mile (96,000 km)
intervals.
SPARK PLUG WIRE INSPECTION
Check the spark plug wires at 60,000 mile (96,000 km)
intervals.
..

FLUID LEVEL CHECK
A fluid loss in any system (except windshield
washer) may indicate a problem. Repair the system
at once.
Engine
oil level -Check level and add if
necessary. The best time to check the engine oil
level is
when the oil is warm. After stopping the
engine with the vehicle on a level surface, wait a
few minutes for the oil to drain back to the oil pan.
Pull
out the oil level indicator (dipstick). Wipe it
clean and push the oil level indicator back down all
the
way. Pull out the oil level indicator, keeping the
tip down, and look at the oil level on it.
Add oil, if needed, to keep the oil level above
the
"ADD" mark and between the "ADD" and
"FULL" marks in the operating range area. Avoid
overfilling the engine since this may cause engine
damage. Push
the oil level indicator back down all
the
way after taking the reading.
If you check the oil level when the oil is cold, do
not run the engine first. The cold oil will not drain
back
to the pan fast enough to give a true oil level.
Engine coolant level and condition -Check
engine coolant level in the coolant reservoir and
add engine
coolant if necessary. Inspect the engine
coolant and replace it if dirty or rusty.
Windshield washer fluid level -Check washer
fluid level in reservoir and add if necessary.
Power steering system reservoir level-Check
and keep at
proper level.
Brake master cylinder reservoir level -Check
fluid. Keep fluid at proper level. A low fluid level
can indicate
worn disc brake pads which may need
to be serviced.
Hydraulic clutch system -Check fluid l~vel in
the reservoir.
Add fluid as required.
Battery fluid level -Check fluid level in the
battery.
FLUID LEAK CHECK
Check for fuel, water, oil or other fluid leaks by
looking at the surface beneath the vehicle after it
has been parked for a while. Water dripping from
the air conditioning system after use is normal. If
you notice gasoline fumes or fluid at any time,
locate the source and correct it at once.
ENGINE OIL AND OIL FILTER
REPLACEMENT
Always use API SE, SF, SG, SH or ILSAC GF-1
quality oils of the proper viscosity.
When choosing an oil, consider the range of
temperatures the car will be operated in before the
next oil change. Then, select the recommended oil
viscosity
from the chart (Fig. OB-1).
Always change the oil and the oil filter as soon as
possible after driving in a dust storm.
MAINTENANCE AND LUBRICATION OB-5
ENGINE COOLING SYSTEM INSPECTION
Inspect coolant/anti-freeze. If coolant is dirty or
rusty, drain, flush and refill with new coolant. Keep
coolant at the proper mixture for proper freeze
protection,
corrosion inhibitor level and best engine
operating temperature.
Inspect hoses and replace if
cracked, swollen or deteriorated. Tighten hose
clamps if equipped with screw-type clamps. Clean
outside of radiator and air conditioning condenser.
Wash
filler cap and neck. To help ensure proper
operation, a pressure test of both the cooling
system and cap is also recommended.
EXHAUST SYSTEM INSPECTION
Visually inspect the exhaust pipes, muffler, heat
shields and hangers
for cracks, deterioration, or
damage.
Be alert to any changes in the sound of the exhaust
system
or any smell of fumes. These are signs the
system may be leaking or overheating. Repair the
system at once,
if these conditions exist. (See also
"Engine Exhaust Gas Safety" and "Three Way
Catalytic Converter" in Owner's manual.)
FUEL CAP, FUEL LINES, AND FUEL TANK
INSPECTION
Inspect the fuel tank, the fuel cap and the fuel lines
every
60,000 miles (96,000 km) for damage which
could cause leakage.
Inspect the fuel cap and the gasket for correct sealing
and physical damage. Replace any damaged parts.
DRIVE BELT INSPECTION
Check the belts driving the steering oil pump, the air
conditioning compressor, and the generator
for
cracks, fraying, wear, and correct tension every 30,000
miles (48,000 km). Adjust or replace as necessary.
WHEEL ALIGNMENT, BALANCE AND
TIRES OPERATION
Uneven or abnormal tire wear, or a pull right or left
on a straight and level road may show the need for
a wheel alignment. A vibration of the steering
wheel or seat at normal highway speeds means a
wheel balancing is needed. Check tire pressure
when the tires are "cold" (include the spare).
Maintain pressure as shown in the tire placard,
which is located on the driver's door lock pillar.
STEERING SYSTEM OPERATION
Be alert for any changes in steering action. An
inspection
or service is needed when the steering
wheel is harder
to turn or has too much free play, or
if there are unusual sounds when turning or parking.

OB-12 MAINTENANCE AND LUBRICATION
MAINTENANCE SERVICE DATA
SERVICE DATA AND SPECIFICATIONS
ENGINE
• Valve clearance I o o I I I 0 0 0 I 0 o o o o o I 0 o o o 0 0 o o o o Zero (Hydraulic adjuster)
• Spark plug type I I o 0 I o 0 I I I 0 o o o I 0 I o o 0 0 0 o o 0 0 0 FR2LS, BKR6E-1 1, K20PR-U11 or equivalent
•
Spark plug gap ............................ 1.05 mm (0.04 in)
• Drive belt tension ..........................
(with a belttension gage)
Generator belt 170-190 lb 100-120 lb
PIS
pump belt 70-110 lb 70-110 lb
A/C compressor belt 100-140 lb 80-120 lb
CLUTCH
• Clutch pedal free play ......................... 5 -15 mm (0.20 -0.59 in)
BRAKE
• Brake pedal free play o o o o o o o o 0 0 o o o o o 0 0 o o 0 I o o o o 6 -10 mm (0.24 -0.39 in)
• Parking brake travel ••••••••••••••••••\
•• 0 ••••• 6-7 notches
WHEEL
ALIGNMENT
•
Toe-in 0 0 o o 0 0 I 0 0 o o o o 0 0 0 0 o o o o I 0 0 o o 0 0 o o o o 0 I 0 0 ± 2 mm (0 ± 0.08 in)
• Camber .................................. oo ± 30'
•
Caster o o o 0 0 0 0 o o o o o o I 0 0 o o o o 0 0 o o o o 0 o o o o o 0 0 o 2° 1 0' ± 45' (Long wheel base model)
2° 00' ± 45' (Short wheel base model)
PROPELLER SHAFT
• Flange torque ••••••••••••••••••\
•• 0' ••• 0 ••• 63 N·m (46 lb·ft)
WHEEL AND TIRES
• Wheel nut torque o o o o 0 0 o o o o o o o o o o o I o o o o 0 0 0 o 118 N·m (87 lb·ft)
* • Tire inflation pressure •••••••••••••• 0 ••• Front 21 0 kPa (30 psi)
Rear
240 kPa (35 psi)
* Unless otherwise specified on tire information label on vehicle.
~~-.... ¢ .............. .-I ~ -.,~iii~-..--. ....... 2 ........ -. .................. ~~ - I

3A-2 FRONT END ALIGNMENT
DEFINITION OF TERMS
CAMBER (Fig. 3A-1)
Camber is the inward or outward tilting of the front
wheels from the vertical. When the wheels tilt outward
at the top, the camber is
positive(+). When the wheels
tilt inward at the top, the camber is negative(-). The
amount
of tilt measured in degrees from the vertical is
called the camber angle.
If camber is extreme or unequal between the wheels,
improper steering and excessive tire
wear will result.
Negative camber causes
wear on the inside of the tire,
while positive camber causes wear to the outside.
Left front view
Positive direction
Fig. 3A-1
CASTER (Fig. 3A-2)
Caster is the tilting of the wheel axis either forward or
backward from the vertical (when viewed from the side
of the vehicle). A backward tilt is positive(+) and a
forward tilt is
negative(-).
On the short and long arm type suspension you cannot
see a caster angle
without a special instrument, but if
you look straight down from the top of the upper
control arm to the ground, the
ball joints do not line up
(fore and aft) when a caster angle other than
0 degree is
present. With a positive angle, the lower
ball joint
would be slightly ahead (toward the front of the
vehicle)
of the upper ball joint center line .
• Front
Fig. 3A-2
TOE-IN (Fig. 3A-3)
Toe-in is the turning of the front wheels. The actual
amount of toe-in is normally a fraction of a degree.
Toe-in is measured
from the center of the tire treads or
from the inside of the tires. The purpose of toe-in is to
insure
parallel rolling of the front wheels and to offset
any
small deflections of the wheel support system
which occurs
when the vehicle is rolling forward.
lncorrecttoe-in results in excessive toe-in and unstable
steering. Toe-in is the last alignment to
be set in the
front end alignment procedure.
Fig. 3A-3
•

WHEELS AND TIRES 3E-1
SECTION 3E
WHEELS AND TIRES
W CAUTION:
When fasteners are removed, always reinstall them at the same location from which they were removed.
If a fastener needs to be replaced, use the correct part number fastener for that application. If the correct
part
number fastener is not available, a fastener of equal size and strength (or stronger) may be used.
Fasteners
that are not reused, and those requiring thread locking compound, will be called out. The correct
torque value must be used when installing fasteners that require it. If the above conditions are not
followed, parts or system damage could result.
CONTENTS
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 E -1 Unit Repair .......................................... 3E-7
Diagnosis ........................................... 3E-2 Tires ............................................... 3E-7
Irregular and Premature Wear ................ 3E-2 Wheels ............................................ 3E-7
Inflation of Tires ................................. 3 E- 3 General Balance Procedure ................... 3E-8
Diagnosis List. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 E- 3 Balancing Wheel and Tire ...................... 3E-8
On-Vehicle Service ................................ 3E-6 Main Data and Specifications .................... 3E-9
Wheels ............................................ 3E-6 General Specifications ......................... 3E-9
Torque Specifications .......................... 3E-9
GENERAL DESCRIPTION
Replacement wheels or tires must be equivalent to
the originals in load capacity, specified dimension
and mounting configuration. Improper size or type
may affect bearing life, brake performance,
speedometer/odometer calibration, vehicle ground
clearance and tire clearance to the body and chassis.
p 245
T Tire type P -Passenger T -Temporary C -Commercial
Section
width (Millimeters) 215 225
245
ETC.
Metric tire sizes 70 R 16 T ,...
Aspect ratio I Rim diameter
(Section height)
(Section
width) X 100 (Inches)
14 60 70
80 ETC.
15
16 ETC.
Construction type
R-Radial
B - Bias-belted
D - Diagonal (Bias)
METRIC TIRE SIZE FORMAT
All model are equipped with metric sized tubeless
steel belted radial
tires. Correct tire pressures and
driving habits have an important influence on tire life.
Heavy cornering, excessively rapid acceleration and
unnecessary sharp braking increase
premature and
uneven wear.
16 X 7 JJ
I
~pe of flange
Rim width 5% 5.5 in.
6 6.0 in. 7 7.0 in.
Rim diameter Rim width
14 14 in. 15 15 in. 16 : 16 in.
I Off Set RIM SIZE FORMAT
Fig. 3E-1

WHEELS AND TIRES 3E-1
TIRES
REPLACEMENT
UNIT REPAIR
WHEELS
REPLACEMENT
When replacement is necessary, the original metric
the size should be used. Most metric tire sizes do not
have exact corresponding alphanumeric tire sizes. It
is recommended that new tires be installed in pairs on
the same axle. If necessary to replace only one tire, it
should be paired with tire having the most tread, to
equalize braking traction.
w CAUTION:
Do not mix different types of tires such as radial,
bias and bias-belted tires except in emergencies,
because
vehicle handling may be seriously
affected and may result in loss of control.
TIRE DISMOUNTING
Remove valve cap on valve step and deflate the tire.
Then use a
tire changing machine to mount or
dismount tires.
Follow the equipment manufacturer's instruction. Do
not use hand tools or tire lever alone to change tires
as they may damage the tire beads or wheel rim.
TIRE MOUNTING
Rim bead seats should be cleaned with a wire brush
....._., or coarse steel wool to remove lubricants, and light
rust. Before mounting a tire, the bead area should be
well lubricated with an approved tire lubricant.
After mounting, inflate the tire to 196kPa (28 psi) so
that beads are completely seated. Inflate the air to
specified pressure and install valve cap to the stem.
\f WARNING:
Never stand over tire when inflating. Bead may
break when bead snaps over rim's safety hump
and cause serious personal injury.
Never exceed
240 kPa (35 psi) pressure when
inflating. If 240 kPa (35 psi) pressure will not
seat beads, deflate, re-lubricate and re-inflate.
Over
inflation may cause the bead to break and
cause serious
personal injury.
TIRE REPAIR
There are many different materials on the market
used to repair tires.
Manufacturers have published detailed instructions
on how and when to repair tires. These instructions
can be obtained from the tire manufacturer if they are
not included with the repair kit. Damaged
wheels and wheels with excessive run-out
must be replaced.
Fig. 3E-10
Wheel
run-out at rim
Steel Aluminum
@ Vertical play: 1.5 (0.059) 0.7
(0.028) Less than mm(in)
@ Horizontal play: 1.5 (0.059) 0.7
(0.028) Less than mm(in)

3E-8 WHEELS AND TIRES
GENERAL BALANCE PROCEDURE
Deposits of mud, etc. must be cleaned from the inside
of the rim.
The tire should be inspected
for the following: match
mount paint marks, bent rims, bulges, irregular tire
wear, proper
wheel size and inflation pressure. Then
balance according to the equipment manufacturer's
recommendations.
There are
two types of wheel and tire balance.
Static balance is the equal distribution
of weight
around the wheel.
Assemblies
that are statically unbalanced cause a
bouncing action
called tramp. This condition will
eventually
cause uneven tire wear (Fig. 3E-11 ).
Dynamic balance is the equal distribution of weight on
each side
of the wheel center-line so that when the tire
spins there
is no tendency for the assembly to move
from side to side. Assemblies that are dynamically
unbalanced may cause shimmy (Fig. 3E-12).
Heavy spot wheel shimmy
Heavy spot wheel tramp
WARNING
Add balance weights here
Corrective weights
Fig. 3E-11
Add balance
weights here
Corrective weights
Fig. 3E-12
Stones should
be removed from the tread to
avoid operator injury during spin balancing and
to obtain a
good balance.
BALANCING WHEEL AND TIRE
ON-VEHICLE
BALANCING
On-Vehicle balancing methods vary with equipment
and tool manufacturers. Be sure to follow each
manufacturer's instructions during balancing
operation.
OFF-VEHICLE BALANCING
Most electronic off-vehicle balancers are more
accurate than the on-vehicle spin balancers. They are
easy to use and give a dynamic balance. Although
they
do not correct for drum or disc unbalance (as on­
vehicle
spin balancing does), they are very accurate
(Fig. 3E-13).
Fig. 3E-13

REAR AXLE 48-3
DIAGNOSIS OF REAR AXLE NOISE
Many noises that seem to come from the rear axle
actually
originate from other sources such as tires,
road surface, wheel bearings, engine, transmission,
muffler,
or body drumming. Investigate to find the
source
ofthe noise before disassembling the rear axle.
Rear axles,
like any other mechanical device, are not
absolutely quiet but should be considered quiet unless
some abnormal noise is present.
To make a systematic check
for axle noise, observe the
following:
1. Select a level asphalt road to reduce tire noise and
body drumming.
2. Check rear axle lubricant level to assure correct
level, and then drive the vehicle far enough to
thoroughly warm up the rear axle lubricant.
3. Note the speed at which noise occurs. Stop the
vehicle and put the transmission in neutral. Run
the engine speed
slowly up and down to
determine if the noise is caused by exhaust,
muffler noise, or other engine conditions.
4. Tire noise changes with different road surfaces;
axle noises do not. Temporarily inflate all tires to
344
kPa (50 psi) (for test purposes only). This will
change noise caused by tires but will not affect
noise caused by the rear
axle.
Rear axle nose usually stops when coasting at
speeds under
48 km/h (30 mph); however, tire
noise continues
with a lower tone. Rear axle noise
usually changes when comparing pull and coast,
but tire noise stays about the same.
Distinguish between tire noise and rear
axle noise
by noting
if the noise changes with various
speeds
or sudden acceleration and deceleration.
Exhaust and
axle noise vary under these
conditions,
while tire noise remains constant and
is more pronounced at speeds
of 32 to 48 km/h
(20 to 30 mph). Further check for tire noise by
driving the vehicle
over smooth pavements or dirt
roads (not gravel) with the tires at normal
pressure.
If the noise is caused by tires, it will
change noticeably with changes in road surface.
5. Loose or rough front wheel bearings will cause
noise
which may be confused with rear axle
noise; however, front wheel bearing noise does
not change when comparing drive and coast.
Light application
of the brake while holding
vehicle speed steady
will often cause wheel
bearing noise to diminish. Front wheel bearings
may be checked for noise by jacking up the
wheels and spinning them
or by shaking the
wheels
to determine if bearings are loose.
6. Rear suspension rubber bushings and spring
insulators dampen
out rear axle noise when
correctly installed. Check to see that there is no
link or rod loosened or metal-to-metal contact.
7. Make sure that there is no metal-to-metal contact
between the
floor and the frame.
After the noise has been determined to be in the axle,
the type of axle noise should be determined, in order to
make any necessary repairs.
GEAR NOISE
Gear noise (whine) is audible from 32 to 89 km/h (20 to
55 mph) under four driving conditions.
1. In drive under acceleration or heavy pull.
2. Driving under load or under constant speed.
3. When using enough throttle to keep the vehicle
from driving the engine while the vehicle slows
down gradually (engine still pulls slightly).
4. When coasting with the vehicle in gear and the
throttle closed. The gear noise is
usually more
noticeable between 48 and 64
km/h (30 and 40
mph) and 80 and 89 km/h (50 and 55 mph).
BEARING NOISE
Bad bearings generally produce a rough growl or
grating sound, rather than the whine typical of gear
noise. Bearing noise frequently
"wow-wows" at
bearing rpm, indicating a bad pinion
or rear axle side
bearing. This noise can
be confused with rear wheel
bearing noise.
REAR WHEEL BEARING NOISE
Rear wheel bearing noise continues to be heard while
coasting at low speed with transmission in the neutral.
Noise may diminish by gentle braking. Jack up the rear
wheels, spin them by hand and
listen for noise at the
hubs. Replace any faulty
wheel bearings.
KNOCK AT LOW SPEEDS
Low speed knock can be caused by worn universal
joints or a side gear hub counter bore in the cage that is
worn oversize. Inspect and replace universal joints or
cage and side gears as required.
BACKLASH CLUNK
Excessive clunk on acceleration and deceleration can
be caused by a worn rear axle pinion shaft, a worn
cage, excessive clearance between the axle and the
side gear splines, excessive clearance between the
side gear hub and the counterbore in the cage,
worn
pinion and side gear teeth, worn thrust washers, or
excessive drive pinion and ring gear backlash.
Remove
worn parts and replace as required. Select
close-fitting parts when possible. Adjust pinion and
ring gear backlash.

ENGINE ELECTRICAL 601-1
SECTION 60
ENGINE ELECTRICAL
CONTENTS
Battery . . ..... . ...... . ... . .... . .... ..... .... . .... .. .... . .... . . ... . . . .... . . .. . . .... . ... . ... . .... . . .. ... . .... . . ... . ... . . .. . Section 601
Cranking System
........... ... . ... . .... . .... . . .... . .... .

. ... . . .... . .... . .... . . ... ...
.. .... . . ..... . .... . ......... ... Section 602
Charging System ..... .... . . .............. .... . .... . . .. .. . . ... . . ... . . ... . . ... . . ........ .... . . ..... .. .... . ... . .... . .. Section 603
Ignition System (V6 3.2L) .. .... ...... ...... .. .. .. .... ...... .... .. .... .... .... ...... ...... ...... .......... .... Section 6D4A
SECTION 601
BATTERY
CONTENTS
General Description ............................... 6D1-1
Diagnosis .............................................. 6D1-1
On-Vehicle Service ................................ 6D1-3
Battery Charging ................................ 6D1-3
Jump Starting .................................... 6D1-3
Removal and Installation of The Battery . . 6D1-4
Main Data and Specifications . . . . . . . . . . . . . . . . . . 6D1-4
GENERAL DESCRIPTION
There are six battery fluid caps at the top of the
battery. These are covered by a paper
label.
The battery is completely sealed except for the six
small vent holes at the side. These vent holes per­
mit the escape of small amounts of gas generated
by the battery.
This type
of battery has the following advantages
over
conventional batteries:
1. There is no need to add water during the entire
service
life of the battery.
2. The battery protects itself against overcharging.
The battery
will refuse to accept an excessive
charge. (A
conventional battery will accept an excessive
charge,
resulting in gassing and loss of battery
fluid.)
3. The battery is much less vulnerable to self­
discharge than a conventional type battery.
DIAGNOSIS
1. VISUAL INSPECTION
Inspect the battery for obvious physical damage,
such
as a cracked or broken case, which would per­
mit electrolyte loss.
Replace
the battery if obvious physical damage is
discovered during inspection.
Check
for any other physical damage and correct it
as necessary. If not, proceed to Step 2.
2. HYDROMETER CHECK
There is a built-in hydrometer (Charge test indica­
tor) at the top of the battery. It is designed to be
used during diagnostic procedures. Before
trying to read the hydrometer,
carefully
clean
the upper battery surface.
If your work area is poorly lit, additional light may
be necessary
to read the hydrometer (Fig. 6D1-1).
a. BLUE RING OR DOT VISIBLE -Go to Step
4.
b. BLUE RING OR DOT NOT VISIBLE -Go to
Step 3.

604-4 IGNITION SYSTEM
Fig. 604A-5
~ INSPECTION AND REPAIR
The spark plug affects entire engine performance and
therefore its inspection is very important.
• Check electrode and insulator for presence of
crack, and replace if any.
• Check electrode for wear, and replace if neces­
sary.
• Check gasket for damage, and replace if neces­
sary.
• Measure insulation resistance with an ohmmeter,
and replace if faulty.
• Adjust spark plug gap to 1.0(0.04) -1.1 (0.043)
mm(in).
• Check fuel and electrical systems if spark plug is
extremely dirty.
• Use spark plugs having low heat value (hot type
plug) if fuel and electrical systems are normal.
• Use spark plugs having high heat value (cold type
plug) if insulator and electrode are extremely
burned.
Sooty spark plugs
Much deposit of carbon or oil on the electrode and
insulator of spark plug reduces the engine perfor­
mance.
Possible causes:
• Too rich mixture
• Retarded ignition timing
• Presence of oil in combustion chamber
• Incorrectly adjusted spark plug gap
Burning electrodes
This fault is characterized by scorched or heavily
oxidized electrode or blistered insulator nose.
Possible causes:
• Too lean mixture
• Advanced ignition timing
• Improper heat value
Measuring Insulation Resistance
• Measure insulation resistance using a 500 volt
megaohm meter. (Fig. 604-6)
Fig.
604-6
• Replace spark plugs if measured value is out of
standard.
I @!.j Insulation resistance MQ 50 or more
Cleaning Spark Plugs
• Clean spark plugs with a spark plug cleaner.
• Raise the ground electrode to an angle of 45 to 60
degrees. If electrode is wet, dry it before cleaning.
• After spark plug is thoroughly cleaned, check
insulator for presence of crack.
• Clean threads and metal body with a wire brush.
• File the electrode tip if electrode is extremely
worn.
• Bend the ground electrode to adjust the spark
plug gap. (Fig. 604-7)
Fig. 604-7
•