Isuzu engine 4j series. Manual - part 11

SERVICE INFORMATION 00 – 43

needle position of water thermomete, conduct a
5 minutes idling again and stop the engine.

10 When the engine has been cooled, check filler neck

for water level and replenish if required. Should
extreme shortage of coolant is found, Check the
coolant system and reservoir tank hose for leakage.

11 Fill the coolant into the reservoir tank up to “MAX”

line.

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 pressure.
Testing Pressure

kPa (Kg/cm

/psi)

147 (1.5/21)

Radiator Cap Inspection

The radiator filler cap is designed to maintain coolant

pressure in the cooling system at 1.05 kg/cm

(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
Pressure Valve

kPa (Kg/cm

/psi)

88 - 118 (0.9 - 1.2/12.8 - 17.1)

Negative Valve (Reference)

kPa (Kg/cm

/psi)

1.0 - 13.9 (0.01 - 0.04/0.14 - 0.57)

Thermostat Operating Test

1. Completely submerge the thermostat in water.
2. Heat the water.

Stir the water constantly by suitable wood bar (2) to
avoid direct heat being applied use wood plate (3) to
the thermostat.

3. Check the thermostat initial opening temperature.
Thermostat Initial
Opening Temperature

°C (°F)

82 (180)

4. Check the thermostat full opening temperature.
Thermostat Full
Opening Temperature

°C (°F)

95 (203)

Valve Lift at Fully Open Position

mm (in)

10 (0.39)

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00 – 44

SERVICE INFORMATION

Drive Belt Adjustment

Depress the drive belt mid portion with a 98N (10 kg/22
lb) force.
Drive Belt Deflection

mm (in)

10 (0.39)

Check the drive belt for cracking and other damage.
1. Crankshaft damper pulley
2. Generator pulley
3. Cooling fan pulley
4. Oil pump pulley or idler pulley
5. Compressor pulley or idle pulley

Cooling Fan Pulley Drive Belt

Fan belt tension is adjusted by moving the generator.
Depress the drive belt mid portion with a 98N (10 kg/22
lb) force.
1. Crankshaft damper pulley
2. Generator pulley
3. Cooling 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 (10 kg/22
lb) force.
Belt Deflection

mm (in)

14 - 17 (0.55 - 0.67)

1. Crankshaft damper pulley
2. Oil pump pulley or idler 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 belt mid portion with a 98N (10 kg/22
lb) force.
Belt Deflection

mm (in)

14 - 17 (0.55 - 0.67)

1. Crankshaft damper pulley
2. Oil pump pulley
3. Compressor pulley or idler pulley

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SERVICE INFORMATION 00 – 45

ENGINE CONTROL

Idling Speed Inspection

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.

Engine Idling Speed

rpm

4JB1 / 4JB1T / 4JB1TC

750 - 790

4JG2

700 - 740

Idling Speed Adjustment

1. Loosen the idling set bolt lock nut on the injection

pump idling set bolt.

2. Adjust the idling speed to the specified range by

turning the idling set bolt.

3. Lock the idling set bolt with the idling set bolt lock nut.
4. Check that the idling control cable is tight (free of

slack).
If required, remove the slack from the cable.

Accelerator Control Cable Adjustment

1. Loosen the accelerator cable clamp bolt.
2. Check that the idling control knob on the instrument

panel is in the engine idling position.

3. Hold the accelerator lever in the fully closed position

and stretch the control cable in the direction indicated
by the arrow to remove any slack.

Accelerator Pedal Adjustment

1. Loosen the lock nut.
2. Adjust bolt height from floor.
Adjust Bolt Height A

mm (in)

18 - 28 (0.71 - 1.1)

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00 – 46

SERVICE INFORMATION

1. Hold the accelerator pedal pad securely by hand, and

give it a full stroke.

2. Adjust the stopper bolt so that the clearance between

the pad stopper bolt and the rear side of the pad
becomes the specified length.

mm (in)

0 - 2 (0 - 0.079)

3. Check to see if the accelerator pedal play is in the

range of 5 to 10mm above the pedal pad.

4. Press down on the accelerator pedal fully and check

to see if the engine rotates at its maximum speed with
each of the linkage in the smooth operation.

5. In the operating range of accelerator pedal and the

injection pump lever returns to their respective original
positions without fail.

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.

Rocker Arm Shaft
Bracket Nut Torque

N∙m (kg∙m/lb∙ft)

54 (5.5/40)

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
compression stroke.

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