Isuzu KB P190. Manual — part 366

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

4JK1

RTW56ASH025701

Legend

1. Grade

2. Front Mark Cut

4JJ1

LNW76ASH001401

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.

LNW21BSH009301

• 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).

LNW61ASH004401

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

LNW61ASH004501

• 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

LNW21BSH009501

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)

LNW21BSH009601

• 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.

LNW21BSH009701

• 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)

LNW21BSH009801

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

LNW21BSH010401

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.

LNW46ASH004601

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.