engine ISUZU TROOPER 1998 Service Repair Manual

00 Ð 26 SERVICE INFORMATION
Engine Cooling
mm (in)
mm (in)
Parts Items Service standardService limit Remarks
Cylinder liner
projection
Cylinder liner outside
diameter0.0-0.1
(0.00-0.0039)
97.011-97.050
(3.8193-3.8209) Cylinder
Block
(cont’ d)
Parts Items Service standardService limit Remarks
Valve opening
temperature
Valve full open
temperature and lift82¡C
(180¡F)
More than 10 (0.39)
at 95¡C (203¡F) Thermostat
Valve opening pressure 88.2 ~ 117.6kpa
(0.899 ~ 1.199kg/cm2/
12.8 ~ 17.0psi) Radiator
cap
Tension (Slackness)
AC generator & fan
pulley drive belt
A/C Compressor drive
belt
P/S pump drive beltNew belt
8-12 (0.31-0.47)
Used belt
8-12 (0.31-0.47)
New belt
7-10 (0.28-0.39)
Used belt
5-8 (0.2-0.31)
New belt
13-16 (0.51-0.63)
Used belt
13-16 (0.51-0.63) Drive belt

SERVICE INFORMATION 00 Ð 27
SERVICING
Servicing refers to general maintenance procedures to be performed by qualified service personnel.
MODEL IDENTIFICATION
Engine Serial Number
The engine number is stamped on the front left hand side of
the cylinder body.
AIR CLEANER
Oil Wetted (Viscous) Type Paper Element (Australia only)
The air cleaner has an oil wetted paper element. No servic-
ing is required until the replacement interval is reached.
Never attempt to clean the element, no matter how dirty it
may appear. The element is designed to provide normal
filtering efficiency until it becomes due for replacement.
Refer to the Item ÒService and MaintenanceÓ in the OwnerÕs
and DriverÕs Manual for general service information.
Dry Type Paper Element
Element cleaning procedures will vary according to the
condition of the element.
Dust Fouled Elemant
Rotate the element with your hand while applying com-
pressed air to the inside of the element. This will blow the
dust free.
392 - 490 (4-5/57-71)
Compressed air pressure
Kpa (Kg/cm2 / Psi)
CAUTION
Do not bang the element against another object in an
attempt to clean it. Damage to the element will result.
Carbon and Dust Fouled Element
1. Prepare a cleaning solution of Isuzu Genuine Element
Cleaner (Donaldson D1400) diluted with water.
2. Submerge the element in the solution for twenty min-
utes.

00 Ð 28 SERVICE INFORMATION
3. Remove the element from the solution and rinse it well
with running water.
Water pressure must not exceed 274 Kpa (2.8 kg/cm
2/40
Psi)
4. Dry the element in a well ventilated area.
An electric fan will hasten drying.
NOTE:
Do not use compressed air or an open flame to dry the
element quickly. Damage to the element will result.
It will usually take two or three days for the element to dry
completely. Therefore, it is a good idea to have a spare on
hand to use in the interim.
LUBRICATING SYSTEM
Main Oil Filter (Cartridge Type Paper Element)
Replacement Procedure
1. Loosen the drain plug to drain the engine oil.
2. Wait a few minutes and then retighten the drain plug.
3. Loosen the used oil filter by turning it counterclockwise
with the filter wrench.
4. Clean the oil cooler fitting face.
This will allow the new oil filter to seat properly.
5. Apply a light coat of engine oil to the O-ring.
6. Turn in the new oil filter until the filter O-ring is fitted
against the sealing face.
7. Use the filter wrench to turn in the filter an additional 1
and 1/4 turns.
Filter Wrench: 5-8840-0200-0
8. Check the engine oil level and replenish to the specified
level if required.
0.7 (0.62/0.74)
lit(Imp qt / US qt) Replenishment Engine Oil
9. Start the engine and check for oil leakage from the main
oil filter.

SERVICE INFORMATION 00 Ð 29
FUEL SYSTEM
Fuel Filter
Replacement Procedure
1. Loosen the used fuel filter by turning it counterclock-
wise with the filter wrench.
Filter Wrench: 5-8840-0253-0 (J-22700)
2. Remove the level sensor from the filter by turning it
counterclockwise with a wrench.
3. Install the level sensor to the new fuel filter with a
wrench.
5. Apply a light coat of engine oil to the O-ring.
6. Turn in the fuel filter until the sealing face comes in
contact with the O-ring.
7. Turn in the fuel filter an additional 2/3 of a turn with a
filter wrench.
Filter Wrench: 5-8840-0253-0 (J-22700)
8. Loosen the bleeder plug on the injection pump overflow
valve.
9. Operate the priming pump until fuel begins to flow from
the fuel filter.
10. Retighten the bleeder plug.
11. Operate the priming pump several times and check for
fuel leakage.
NOTE:
The use of an ISUZU genuine fuel filter is strongly recom-
mended.
13 (1.3/9)
N·m (Kg·m/lb·ft) Level Sensor Torque
4. Clean the filter cover fitting faces.
This will allow the new fuel filter to seat properly.

00 Ð 30 SERVICE INFORMATION
Fuel Filter Water Draining Procedure
The indicator light will come on when the water level in the
water separator exceeds the specified level.
Drain the water and foreign material from the water separa-
tor with the following procedure.
1. Find a safe place to park the vehicle.
2. Open the engine hood and place a container (Approxi-
mately 0.2 liter capacity) at the end of the vinyl hose
beneath the drain plug on the separator.
3. Loosen the drain plug by turning it counterclockwise
(Approximately 5 turns) and operate the priming pump
up and down about 10 times until water is drained
approximately 0.1 liter.
4. After draining, securely tighten the drain plug by turn-
ing it clockwise and operate the priming pump manu-
ally up and down several times.
5. After starting the engine, check to see that there is no
fuel leak from the drain plug.
Also check to see that the fuel filter water indicator light
has turned off.
If water separator requires frequent draining, have the
fuel tank drained for removal of water at your Isuzu
Dealer.
Air Bleeding
1. Loosen the bleeder screw on the injection pump over-
flow valve.
2. Operate the priming pump until fuel mixed with foam
flows from the bleeder screw.
3. Tighten the bleeder screw.
4. Operate the priming pump several times and check for
fuel leakage.
COOLING SYSTEM
Coolant Level
Check the coolant level and replenish the radiator reserve
tank as necessary.
If the coolant level falls below the ÒMINÓ line, carefully check
the cooling system for leakage. Then add enough coolant to
bring the level up to the ÒMAXÓ line.
NOTE:
Do not overfill the reserve tank.

SERVICE INFORMATION 00 Ð 31
Remove the radiator filler cap only when absolutely neces-
sary.
Always check the coolant level when the engine is cold.
Always refer to the chart at the left to determine the correct
cooling water to antifreeze solution mixing ratio.
Cooling System Inspection
Install a radiator filler cap tester to the radiator. Apply
testing pressure to the cooling system to check for leakage.
The testing pressure must not exceed the specified pres-
sure.
Radiator Cap Inspection
The radiator filler cap is designed to maintain coolant pres-
sure in the cooling system at 1.05 kg/cm
2 (15 psi/103 kPa).
Check the radiator filler cap with a radiator filler cap tester.
The radiator filler cap must be replaced if it fails to hold the
specified pressure during the test procedure.
Radiator Filler Cap Pressure
Thermostat Operating Test
1. Completely submerge the thermostat in water.
2. Heat the water.
Stir the water constantly to avoid direct heat being
applied to the thermostat.
3. Check the thermostat initial opening temperature.
82 (180)
°C(°F) Thermostat Initial
Opening Temperature
4. Check the thermostat full opening temperature.
1.0 – 3.9 (0.01 – 0.04/0.14 – 0.57)
Negative Valve (Reference)Kpa (Kg/cm2 / Psi)
90 (194)
°C(°F) Thermostat Full
Opening Temperature
10 (0.39)
mm(in) Valve Lift at Fully Open Position
196 (2/28.45)
Testing Pressure Kpa (Kg/cm2 / Psi)
93.3 – 122.7 (0.95 – 1.25/13.5 –17.8)
Pressure Valve
Kpa (Kg/cm2 / Psi)

SERVICE INFORMATION 00 Ð 33
ENGINE CONTROL
Idling Speed Adjustment
1. Set the vehicle parking brake and choke the drive wheels.
2. Place the transmission in neutral.
3. Start the engine and allow it to warm up.
4. Disconnect the engine control cable from the control
lever.
5. Set a tachometer to the engine.
6. Check the engine idling speed.
If the engine idling speed is outside the specified range,
it must be adjusted.
Fast Idling Speed Adjustment
1. Loosen the fast idle actuator lock nut 1 .
2. Adjust the fast idling speed by turning the adjusting
screw 2 .
3. Tighten the lock nut 1 .
4. Connect the vacuum hose to the fast idle actuator.
5. Connect the other vacuum hose to the vacuum switch-
ing valve.750 (4JG2-NA)/720 (4JG2-T)
rpm Engine Idling Speed
Idling Speed Adjustment
1. Loosen the idling set screw lock nut 1 on the injection
pump idling set bolt.
2. Adjust the idling speed to the specified range by turning
the idling set bolt 2.
3. Lock the idling set bolt with the idling set screw lock nut.
4. Check that the idling control cable is tight (free of slack).
If required, remove the slack from the cable.
Fast Idling Speed Inspection
1. Set tachometer to the engine.
2. Disconnect the vacuum hose from the fast idle actuator
1 on the injection pump.
3. Disconnect the other vacuum hose 2 from the vacuum
switching valve 3 and connect it to the fast idle actuator
1 .
The vacuum line will now be connected directly from
the vacuum pump 4 to the fast idle actuator.
4. Check the engine fast idling speed.
If the engine idling speed is outside the specified range,
it must be adjusted.
850 – 950
rpm Fast Idling Speed

00 Ð 34 SERVICE INFORMATION
Accelerator Control
Accelerator Control Cable Adjustment
1. Loosen the accelerator cable clamp bolt 1 .
2. Check that the idling control knob on the instrument
panel is in the engine idling position.
3. Hold the accelerator lever 2 in the fully closed position
and stretch the control cable 3 in the direction indi-
cated by the arrow to remove any slack.
Accelerator Pedal Adjustment
1. Depress the accelerator pedal and hold it.
2. Use the stopper bolt 1 to adjust the clearance between
the stopper bolt end and the accelerator pedal lower
face 2 .
VALVE CLEARANCE ADJUSTMENT
1. Bring the piston in either the No. 1 cylinder or the No. 4
cylinder to TDC on the compression stroke by turning
the crankshaft until the crankshaft damper pulley TDC
line is aligned with the timing pointer.
2. Check the rocker arm shaft bracket nuts for looseness.
Tighten any loose rocker arm shaft bracket nuts before
adjusting the valve clearance.
3. Check for play in the No. 1 intake and exhaust valve push
rods.
If the No. 1 cylinder intake and exhaust valve push rods
have play, the No. 1 piston is at TDC on the compression
stroke.
If the No.1 cylinder intake and exhaust valve push rods
are depressed, the No. 4 piston is at TDC on the com-
pression stroke.
54 (5.5/40)
N·m(Kg·m/lb·ft) Rocker Arm Shaft
Bracket Nut Torque2 – 5 (0.08 – 0.20)
mm(in) Accelerator and
Stopper Bolt Clearance

SERVICE INFORMATION 00 Ð 35
Adjust the No. 1 or the No. 4 cylinder valve clearances while
their respective cylinders are at TDC on the compression
stroke.
0.4 (0.016)
mm(in) Valve Clearance (At Cold)
4. Loosen each valve clearance adjusting screw as shown
in the ilustration.
5. Insert a feeler gauge of the appropriate thickness be-
tween the rocker arm and the valve stem end.
6. Turn the valve clearance adjusting screw until a slight
drag can be felt on the feeler gauge.
7. Tighten the lock nut securely.
8. Rotate the crankshaft 360°.
9. Realign the crankshaft damper pulley TDC notched line
with the timing pointer.
10. Adjust the clearances for the remaining valves as shown
in the illustration.
INJECTION TIMING ADJUSTMENT
1. Set the No. 1 cylinder to Top Dead Center.
2. Remove injector pump distributor head plug.
3. Cancel Wax CSD with the handle of a screw driver.
4. Fit a dial gauge and set lift to 1 mm.
5. Set crankshaft damper pulley Top Dead Center mark
about 45° before Top Dead Center from the pointer.
6. Set dial gauge in the ÒOÓ position.
Measuring device : 5-8840-0145-0
7. Turn the crankshaft a little rightwise and leftwise and
see it the pointer is stable in the ÒOÓ position.
8. Turn the crankshaft in the normal direction and read the
measuring deviceÕs indication at TDC (4JG2-T) or 1°
ATDC (4JG2-NA).
9. If the injection timing is outside the specified range,
continue with the following steps.
10. Loosen the injection pump fixing nuts and bracket bolts.
11. Adjust the injection pump setting angle.
¥ If injection timing will be advanced, move the injec-
tion pump toward the engine.
¥ If injection timing will be retarded, move the injec-
tion pump away from the engine.
Tighten the pump fixing nut, adjust bolt and pump distribu-
tor head plug to the specified torque.
19(1.9/13)
N·m(Kg·m/lb·ft) Pump Fixing Bolt
0.5 (0.02)
mm(in) Starting Timing

00 Ð 36 SERVICE INFORMATION
CAUTION
¥ When installing the distributor head plug, be sure to use
new copper washer.
COMPRESSION PRESSURE MEASURE-
MENT
1. Start the engine and allow it to idle until the coolant
temperature reaches 70 Ð 80°C (158 Ð 176°F).
2. Remove the following parts.
* Glow plugs
* Fuel cut solenoid connector
* QOS (Quick-On Start System) fusible link wire at the
connector.
3. Set the adapter and compression gauge to the No. 1
cylinder glow plug hole.
Compression Gauge
(with Adapter): 5-8840-2675-0
Adapter: 5-8531-7002-0
5. Repeat the procedure (Steps 3 and 4) for the remaining
cylinders.
If the measured value is less than the specified limit,
refer to ÒTroubleshootingÓ in this Manual.
17 (1.7/12)
N·m(Kg·m/lb·ft) Injection Pump
Distributor Head Plug
4. Turn the engine over with the starter motor and take the
compression gauge reading.
40(4.1/30)
N·m(Kg.m/lb·ft) Adjust Bolt
Kpa (Kg/cm2 / Psi)
Standard Limit
2940 (30/426) 2157 (22/313) Compression Pressure at 200 rpm