Isuzu engine 4j series. Manual - part 12

 

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Isuzu engine 4j series. Manual - part 12

 

 

SERVICE INFORMATION  00 – 47

Adjust the No. 1 or the No. 4 cylinder valve clearance
while their respective cylinders are at TDC on the
compression stroke.

Valve Clearance (At Cold)

mm (in)

                                                                                                                   

0.4 (0.016)

                                                                                                                   

4. Loosen each valve clearance adjusting screw as

shown in the illustration.

5. Insert a feeler gauge of the appropriate thickness

between 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 clearance for the remaining valves as

shown in the illustration.

INJECTION TIMING ADJUSTMENT

1. Check that the notched line on the injection pump

flange is aligned with the front plate or the timing gear
case notched line.

2. Bring the piston in the No. 

!

 cylinder to TDC 1 on the

compression stroke by turning the crankshaft until the
crankshaft pulley TDC line is aligned with the timing
mark 

"

.

Note:

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.

3. Disconnect the injection pipe from the injection pump.
4. Remove one bolt from the distributor head.
5. Insert a screwdriver into a hole in the fast idle lever

and turn the lever to release the W-C.S.D. function. (If
so equipped)

6. Install the static timing gauge 

#

.

The probe of the gauge should be depressed inward
approximately 2 mm (0.079 in).
Static Timing Gauge : 5-8840-0145-0 (J-28827)

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00 – 48

  SERVICE INFORMATION

7. Rotate the crankshaft to bring the piston in the No. 1

cylinder to a point 30 - 40° BTDC.

8. Set the timing gauge needle to zero.
9. Move the crankshaft pulley slightly in both directions

to check that the gauge indication is stable.

10. Turn the crankshaft clockwise and read the gauge

indication when the crankshaft pulley timing mark is
aligned with the pointer.

mm (in)

4JB1

BTDC 14°

4JB1T

BTDC 11°

4JB1TC

BTDC  4°

4JG2

ATDC  2°

Standard Reading

mm (in)

                                                                                                                   

0.5 (0.02)

                                                                                                                   

If the injection timing is outside the specified range,
continue with the following steps.

11. Loosen the injection pump fixing nuts and bracket

bolts.

12. Adjust the injection pump setting angle.

When large than

standard value

When smaller than

standard value

Gear drive

A

B

A : Move the injection pump toward the engine.
B : Move the injection pump away from the engine.
Tighten the pump fixing nut, adjust bolt and pump
distributor head plug to the specified torque.
Pump Fixing Bolt

N∙m (kg∙m/lb∙ft)

                                                                                                                   

24 (2.4/17)

                                                                                                                   

Adjust Bolt

N∙m (kg∙m/lb∙ft)

                                                                                                                   

19 (1.9/14)

                                                                                                                   

Injection Pump
Distributor Head Plug

N∙m (kg∙m/lb∙ft)

                                                                                                                   

17 (1.7/12)

                                                                                                                   

CAUTION

When installing the distributor head/plug, be sure
to use new copper washer.

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SERVICE INFORMATION  00 – 49

COMPRESSION PRESSURE MEASURE-
MENT

1. Start the engine and allow it to idle until the coolant

temperature reaches 70 - 80°C (158 - 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): 5-8840-2008-0 (J-29762)
Adapter: 5-8531-7001-0

4. Turn the engine over with the starter motor and take

the compression gauge reading.

Compression Pressure at 200 rpm

kPa (Kg/cm

2

/psi)

Standard

Limit

4JB1

3,038 (31/441)

2,157 (22/313)

4JG2

3,334 (34/484)

2,452 (25/356)

5. Repeat the procedure (Steps 3 and 4) for the

remaining cylinders.
If the measured value is less than the specified limit,
refer to “Troubleshooting” in this Manual.

QUICK-ON START II SYSTEM
(4JB1 / 4JB1T / 4JB1TC only)

Quick-On Start System Inspection Procedure

1. Disconnect the thermo-sensor connection on the

thermostat outlet pipe.

2. Turn the starter switch to the “ON” position.

If the Quick-On Start II System is operating properly,
the glow relay will make a clicking sound within 15
seconds after the starter switch is turned on.

3. Measure the glow plug terminal voltage with a circuit

tester immediately after turning the starter switch to
the “ON” position.

Glow Plug Terminal Voltage

V

                                                                                                                   

Approx. 11

                                                                                                                   

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00 – 50

  SERVICE INFORMATION

QUICK-ON START III SYSTEM
(4JG2 only)

Quick-On Start System Inspection Procedure

1. Disconnect the thermo-sensor connection on the

thermostat outlet pipe.

2. Turn the starter switch to the “ON” 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.

3. Measure the glow plug terminal voltage with a circuit

tester immediately after turning the starter switch to
the “ON” position.

Glow Plug Terminal Voltage

V

                                                                                                                   

8 – 9

                                                                                                                   

NOTE:

Electrical power to the quick-on start system will be
cut after the starter has remained in the “ON”
position for twenty seconds.

Turn the starter switch to the “OFF” position and
back to the “ON” position.

This will reset the Quick-On Start III System.

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