Isuzu KB P190. Manual - part 366

6A-104  ENGINE MECHANICAL (4JK1/4JJ1) 

4JK1 
 

 
 
 

 

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Legend 

 1. Grade 

  2.  Front Mark Cut 

 

 
4JJ1 
 

 
 
 

 

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Legend 

 1. Grade 

  2.  Front Mark Cut 

 

8.  Inspect the piston ring. 

•  Insert the piston ring horizontally (in the position

it would assume if it were installed to the

piston) into the cylinder block. 

 

 

 

 

 

 

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•  Push the piston ring into the cylinder bore until 

it reaches the measuring point 1 or 2 where the 

cylinder block bore is the smallest. 

 

Do not allow the piston ring to slant to one side 

or the other. It must be perfectly horizontal.  

 

Measuring Point 1 

10 mm (0.4 in) 

  

or 

 

Measuring Point 2 

120 mm (4.7 in). 

 

 

 

 

 

 

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ENGINE MECHANICAL (4JK1/4JJ1)  6A-105 

 

 
 

 

 

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•  Use a thickness gauge to measure the piston

ring gap. 

  If the measured value exceeds the specified

limit, the piston ring must be replaced.  

  Piston ring gap 

mm (in)

 Standard 

Limit 

1st compression ring 

0.3 - 0.5 

(0.0118 - 0.0197) 

1.50 

(0.059) 

2nd compression ring 

0.3 - 0.5 

(0.0118 - 0.0197) 

1.50 

(0.059) 

Oil ring 

0.25 - 0.45 

(0.0098- 0.0177) 

1.50 

(0.059) 

  Measure the clearance between the piston ring

groove and the piston. 
•  Remove carbon in the piston ring groove. 
•  Put the piston ring in the piston ring groove, use

a thickness gauge to measure the gap between

them. 

•  If the clearance between the piston ring groove 

and the piston exceeds the limit, replace the 

piston and the piston ring. 

 

  Piston ring and piston ring groove clearance  mm (in)

 Standard 

Limit 

1st compression ring 

— 

∗

 — 

∗

 

2nd compression ring

0.05 - 0.09 

(0.0020 - 0.0035)

1.50 

(0.059) 

Oil ring 

0.03 - 0.07 

(0.0012- 0.0028)

1.50 

(0.059) 

∗ 

Measurement is impossible 

 
 

 

 

 

 

 

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9.  Inspect the piston pin. 

•  Visually inspect the piston pin for cracks, 

scratches and other damage, and replace it if 

necessary. 

• Use a micrometer to measure the outer 

diameter of the piston pin.  If the measured 

value exceeds the limit, replace the piston pin.

  Piston pin outer diameter 

mm (in)

Standard 

33.995 – 34.000 (1.33838 – 1.33858)

Limit 33.970 

(1.33740) 

 

 

 

6A-106  ENGINE MECHANICAL (4JK1/4JJ1) 

 

 

 

 

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•  Inspect to make sure that there is a resistance

to the extent which the piston can push the

piston pin lightly in normal temperatures. 

•  If it feels a large looseness or instability in

normal temperatures, replace the piston or 

piston pin. 

 

 

 

 

 

 

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•  Measure the bush of the small edge of the

connecting rod.  If the clearance of the bush inner

diameter and the pin diameter exceeds the limit,

replace the bush or connecting rod assembly, and

the pin. 

  Piston pin and connecting rod small end bushing 

clearance mm 

(in)

Standard 

0.008 - 0.020 (0.0003 - 0.0008) 

Limit 0.05 

(0.0020) 

 

 

 

 

 

 

 

 

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10. 

 Measure the clearance between the piston and 

the piston pin. 
•  Apply engine oil on the piston pin.  Use your 

finger to push it in the piston hole and rotate it. 

If the pin smoothly rotates without instability, 

the clearance is normal.  If there is instability, 

measure the clearance.  If the clearance 

exceeds the limit, replace the piston and the 

piston pin. 

  Piston pin and piston pin hole clearance 

mm (in)

Standard 

0.004 - 0.017 (0.0002 - 0.0007) 

Limit 0.04 

(0.0016) 

11. Measure the connecting rod alignment. 

•  Use a connecting rod aligner to measure the 

torsion and parallel level of the big end hole 

and the small end hole.  If the measured value 

exceeds the limit, replace it. 

  Connecting rod alignment 

(par length of 100 mm (3.94 in)) 

mm (in)

 Standard 

Limit 

Distortion 

0.08 (0.003) or less 

0.20 (0.008) 

Parallelism 

0.05 (0.002) or less 

1.50 (0.060) 

 

ENGINE MECHANICAL (4JK1/4JJ1)  6A-107 

 

 

 

 

 

 

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12.  Measure the bearing oil clearance. 

•  Install the bearing to the connecting rod big

end. 

•  Tighten the bearing cap to the two step of

angular tightening method. 

•  Use an inside dial indicator to measure the

connecting rod bearing inside diameter.  

  Connecting rod bearing cap bolt torque: 

 

N

⋅m (kg⋅m / lb ft)

1st step 

29.4 (3.0 / 22) 

2nd step 

45 deg 

  If the clearance between the measured bearing

inside diameter and the crankpin exceeds the

specified limit, the bearing and/or the crankshaft

must be replaced.  

  Crankpin and bearing clearance 

mm (in)

Standard 

0.029 - 0.083 (0.0011 - 0.0033) 

Limit 0.10 

(0.0039) 

Reassembly 

1.  Install the piston. 

2.  Install the connecting rod. 

•  Install it so that the front mark of the head of

the piston, and the connecting rod forging mark

(projecting) on the connecting rod, both face in 

the same direction. 

•  Install the snap ring of one side. 

 

 

 
 
 
 
 

 

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Legend 

 1. Front 

Mark 

  2.  Forging Mark (Projecting) 

 

4.  Apply enough engine oil on the piston pin, push it 

in the piston and the connecting rod small edge. 

5.  Use snap ring pliers to install the snap ring. 

Note: 
Make sure that the snap ring is installed in the ring
groove properly. Make sure that the connecting rod 
moves smoothly. 

 

 
 
 
 

 

015R100001

6.  Use ring pliers to install the piston ring. 

•  Install the piston rings in the order shown in the 

illustration. 

•  Install 2nd and 1st compression rings in this 

order so that the marks “2N” and “N” face 

upward.