ISUZU TROOPER 1998 Service Repair Manual

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)

00 Ð 32 SERVICE INFORMATION
Drive Belt Adjustment
Check the drive belt tension.
Depress the drive belt mid-portion with a 98N (10kg/22 lb)
force.
Cooling Fan Pulley Drive Belt
Fan belt tension is adjusted by moving the alternator.
Depress the drive belt mid-portion with a 98N (10Kg/22lb)
force.
1Crankshaft damper pulley
2Alternator pulley
3Cooling fan pulley
Compressor Pulley Drive Belt
Move the idler pulley as required to adjust the compressor
drive belt tension.
If the vehicle is equipped with power steering, move the oil
pump as required.
Depress the drive belt mid-portion with a 98N (10Kg/22lb)
force.
1Crankshaft damper pulley
2Oil pump pulley or idler pulley
3Compressor pulley
Power Steering Oil Pump Pulley Drive Belt
Move the oil pump as required to adjust the oil pump drive
belt tension.
On air conditioner equipped models, both drive belts pulley
must always be replaced as a set.
Depress the drive mid-portion with a 98N (10kg/22 lb) force.
1Crankshaft damper pulley
2Oil pump pulley
3Compressor pulley or idler pulley Check the drive belt for cracking and other damage.
1Crankshaft damper pulley.
2Alternator pulley
3Cooling fan pulley
4Oil pump pulley or idler pulley
5Compressor pulley or idler pulley
10 (0.39)
mm(in) Drive Belt Deflection

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

SERVICE INFORMATION 00 Ð 37
3. Measure the glow plug terminal voltage with a circuit
tester immediately after turning the starter switch to the
ÒONÓ position.
8 – 9
V Glow Plug Terminal Voltage
QUICK-ON START III SYSTEM
Quick-On Start System Inspection Procedure
1. Disconnect the thermo-sensor connection on the ther-
mostat outlet pipe.
2. Turn the starter switch to the ÒONÓ position.
If the Quick-On Start III System is operating properly,
the glow relay will make a clicking sound within seven
seconds after the starter switch is turned on.
NOTE:
Electrical power to the quick-on start system will be cut
after the starter has remained in the ÒONÓ position for ten
seconds.
Turn the starter switch to the ÒOFFÓ position and back to
the ÒONÓ position.
This will reset the Quick-On Start III System.
Nut and Bolt Angular Tightening Method
(Using The Special Tool)
1. Carefully wash the nuts and bolts to remove all oil and
grease.
2. Apply engine oil to the threads and setting faces of the
nuts and bolts.
3. Use a torque wrench to tighten the nuts and bolts to the
specified torque (snug torque).
4. Attach the angle gauge to the socket wrench.
Angle Gauge: 5-88400-266-0
5. Attach a magnet to some part to hold the angle gauge
stationary.
6. Tighten the nuts and bolts to the specified angle, noting
the angle gauge indication.

00 Ð 38 SERVICE INFORMATION
FIXING TORQUE
CYLINDER HEAD COVER, CYLINDER HEAD ROCKER,
SHAFT BRAKER
Nám (Kgám/lbáft)

SERVICE INFORMATION 00 Ð 39
Crankshaft Bearing Cap, Connecting Rod Bearing Cap, Crankshaft Damper
Pulley, Flywheel, Crank Case
Nám (Kgám/lbáft)

00 Ð 40 SERVICE INFORMATION
Gear Case, Timing Gear, Camshaft Nám (Kgám/lbáft)