Isuzu KB P190. Manual - part 209

ENGINE MECHANICAL   6A – 31 

 

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. 

 

 

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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) 

 

 

 

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

Valve Clearance (At Cold) 

mm (in)

0.4 (0.016) 

 

9.  Loosen each valve clearance adjusting screw as 

shown in the illustration. 

10.  Insert a feeler gauge of the appropriate thickness 

between the rocker arm and the valve stem end. 

 

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11.  Turn the valve clearance adjusting screw until a slight 

drag can be felt on the feeler gauge. 

12.  Tighten the lock nut securely. 

13.  Rotate the crankshaft 360

°. 

14.  Realign the crankshaft damper pulley TDC notched 

line with the timing pointer. 

15.  Adjust the clearances for the remaining valves as 

shown in the illustration. 

 

 

6A – 32  ENGINE MECHANICAL 

 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
 
 
 
 

 
 

COMPRESSION PRESSURE 
MEASUREMENT 

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. 

•  Leak off pipe 
•  Injection nozzle holder bracket 
•  Injection nozzle holder 

3.  Install the following parts. 

•  Set the adapter and compression gauge (SST) to 

the No.1 cylinder injection nozzle hole. 

•  Injection nozzle holder bracket 

 

Injection nozzle holder bracket Bolt Torque 
 

N·m (kg·m /lb·ft)

37 (3.8/27) 

 

Compression Gauge: 5-8840-2675-0 

Adapter; Compression Gauge: 5-8531-7001-0 

 

 

 

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

the compression gauge reading. 

 

Compression Pressure 

MPa (kg/cm

2

 /psi) at 200 rpm

Standard Limit 

3.0  (31.0/441) 

2.1 (21.7/309) 

 

 

 

 

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. 

F06XL056

901R100003

ENGINE MECHANICAL   6A – 33 

INJECTION TIMING ADJUSTMENT 
 (4JA1T(L) only) 

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. 1 cylinder to TDC 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. 

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3.  Disconnect the injection pipe from the injection pump 

4.  Remove one bolt from the distributor head. 

5.  Install the adapter set, togather with 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) 

Adapter Set: Static Timing Gauge: 5-8840-2834-0 

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

cylinder to a point 30 - 40

° BTDC. 

7.  Set the timing gauge needle to zero. 

8.  Move the crankshaft pulley slightly in both directions to 

check that the gauge indication is stable. 

6A – 34  ENGINE MECHANICAL 

 

 

  

 

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9.  Turn the crankshaft clockwise and read the gauge 

indication when the crankshaft pulley timing mark (8

°) 

is aligned with the pointer. 

 

Injection Timing : BTDC 8

° ± 2° 

 

Standard Reading 

mm (in)

0.5 (0.02) 

 

 

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. 

When large than standard 

value 

When smaller than standard 

value 

R A 

 

 

A:  Move the injection pump toward the engine. 

R:  Move the injection pump away from the engine. 

12. Install the distributor head bolt. 

Distributor head bolt torque                        N·m (kg·m /lb·ft)

29 (3.0/22) 

 

 

 

 

 

ENGINE CONTROL (4JA1T(L) only) 

Idling Speed Adjustment 

1.  Set the vehicle parking brake and chock the drive 

wheels. 

2.  Place the transmission in neutral. 

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

temperature reaches 70 - 80

°C (158 - 176°F). 

 

 

 

 

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 : 730 

± 25 rpm