2007 ISUZU KB P190 Engine

6A – 74 ENGINE MECHANICAL










Piston Grade Selection
Measure the cylinder liner bore after installing the cylinder liner.
Then select the appropriate piston grade for the installed
cylinder liner.
1. Measure the cylinder liner bore. Refer to "Cylinder Liner Bore Measurement"

Cylinder Liner Bore (Service Part) Grade mm (in)
Grade Bore measurement
AX 93.035-95.050
(3.6628-3.6634) 4JA1T(L) 4JA1TC CX 93.051-95.066
(3.6634-3.6640)
AX 95.435-95.450
(3.7573-3.7579)
4JH1TC
CX 95.451-95.466
(3.7579-3.7585)

NOTE:
It is most important that the correct piston grade be
used. Failure to select the correct piston grade will
result in engine failure. Always measure the cylinder
bore and select the correct piston grade.

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ENGINE MECHANICAL 6A – 75










































2. Measure the piston diameter.

Piston Measuring Point mm (in)
4JA1T(L) 4JA1TC 78 (3.07)
4JH1TC 70
(2.76)


Piston Grade (Service Part) mm (in)
AX 92.949 - 92.964
(3.6549 - 3.6600)
4JA1T(L) 4JA1TC CX 92.965 - 92.980
(3.6600 - 3.6606)
AX 95.359 - 95.374
(3.7542 - 3.7548)
4JH1TC
CX 95.375 - 95.390
(3.7548 - 3.7555)


Cylinder Liner and Piston Clearance mm (in)
4JA1T(L) 4JA1TC 0.041-0.071 (0.0016-0.0027)
4JH1TC 0.047-0.065
(0.0019-0.0026)

NOTE:
Cylinder liner kit clearances are preset. However, the
cylinder liner installation procedure may result in
slight decreases in cylinder liner clearances. Always
measure the cylinder liner clearance after installation
to be sure that it is correct.



TAPPET AND PUSH ROD
Visually inspect the tappet contact surfaces for pitting,
cracking, and other abnormal conditions. The tappet must be
replaced if any of these conditions are present.
Refer to the illustration at the left.
1. Normal contact
2. Cracking
3. Pitting
4. Irregular contact Uneven contact
5. Irregular contact One-sided contact

NOTE:
The tappet surfaces are spherical. Do not attempt to
grind them with an oil stone or similar tool in an effort
to repair the tappet. If the tappet is damaged, it must
be replaced.


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6A – 76 ENGINE MECHANICAL
Tappet Outside Diameter
Measure the tappet outside diameter with a micrometer.
If the measured value is less than the specified limit, the tappet
must be replaced.

Tappet Outside Diameter mm (in)
Standard Limit
12.97 - 12.99
(0.510 - 0.511) 12.95 (0.510)




Tappet and Cylinder Body Clearance mm
(in)
Standard Limit
0.01 - 0.046
(0.0004 - 0.0018) 0.10 (0.004)






























Push Rod Curvature
1. Lay the push rod on a surface plate.
2. Roll the push rod along the surface plate and measure the push rod curvature with a thickness gauge.
If the measured value exceeds the specified limit, the push
rod must be replaced.

Pushrod Curvature mm (in)
Limit
0.3 (0.012)

3. Visually inspect both ends of the push rod for excessive wear and damage. The push rod must be replaced if these
conditions are discovered during inspection.
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ENGINE MECHANICAL 6A – 77


CAMSHAFT
Visually inspect the journals, the cams, the oil pump drive gear,
and the camshaft bearings for excessive wear and damage.
The camshaft and the camshaft bearings must be replaced if
these conditions are discovered during inspection.














Camshaft Journal Diameter
Use a micrometer to measure each camshaft journal diameter
in two directions (1 and 2). If the measured value is less than
the specified limit, the camshaft must be replaced.

Camshaft Journal Diameter mm (in)
Standard Limit
49.945 - 49.975
(1.9663 - 1.9675) 49.60 (1.953)














Cam Height
Measure the cam height (H) with a micrometer. If the
measured value is less than the specified limit, the camshaft
must be replaced.

Cam Height (H) mm (in)
Standard Limit
42.016 (1.6542) 41.65 (1.640)



















Camshaft Run-Out
1. Mount the camshaft on V-blocks.
2. Measure the run-out with a dial indicator. If the measured value exceeds the specified limit, the
camshaft must be replaced.

Camshaft Run-Out mm (in)
Standard Limit
0.02 (0.0008) 0.10 (0.004)

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6A – 78 ENGINE MECHANICAL
Camshaft and Camshaft Bearing Clearance
Use an inside dial indicator to measure the camshaft bearing
inside diameter.

Crankshaft Bearing Inside Diameter mm (in)
Standard Limit
50.00 - 50.03
(1.968 - 1.970) 50.08 (1.972)
If the clearance between the camshaft bearing inside diameter
and the journal exceeds the specified limit, the camshaft
bearing must be replaced.

Camshaft Bearing Clearance mm (in)
Standard Limit
0.055 (0.0022) 0.12 (0.005)










Camshaft Bearing Replacement
Camshaft Bearing Removal
1. Remove the cylinder body plug plate.
2. Use the bearing replacer to remove the camshaft bearing. Bearing Replacer: 5-8840-2038-0









Camshaft Bearing Installation
1. Align the bearing oil holes with the cylinder body oil holes.
2. Use the replacer to install the camshaft bearing. Bearing Replacer: 5-8840-2038-0



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ENGINE MECHANICAL 6A – 79




CRANKSHAFT AND BEARING
Inspect the surface of the crankshaft journals and crankpins for
excessive wear and damage.
Inspect the oil seal fitting surfaces for excessive wear and
damage.
Inspect the oil ports for obstructions.

NOTE:
To increase crankshaft strength, tufftriding (Nitrizing
Treatment) has been applied. Because of this, it is not
possible to regrind the crankshaft surfaces.
Therefore, under size bearing are not available.























Crankshaft Run-Out
1. Set a dial indicator to the center of the crankshaft journal.
2. Gently turn the crankshaft in the normal direction of rotation.
Read the dial indicator as you turn the crankshaft.
If the measured value exceeds the specified limit, the
crankshaft must be replaced.

Crankshaft Run-Out mm (in)
Standard Limit
0.05 (0.002) or less 0.08 (0.003)















Bearing Spread
Use a vernier caliper to measure the bearing spread.
If the measured value is less than the specified limit, the
bearing must be replaced.

Bearing Spread mm
(in)
Limit
4JA1T (L), 4JA1TC 64.5 (2.54)
Creankshaft Bearing
4JH1TC 74.5 (2.93)
Connecting Rod Bearing 56.5 (2.22)


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6A – 80 ENGINE MECHANICAL

Crankshaft Journal and Crankpin Diameter
1. Use a micrometer to measure the crankshaft journal
diameter across points 1 - 1 and 2 - 2.
2. Use the micrometer to measure the crankshaft journal diameter at the two points (3 and 4).
3. Repeat Steps 1 and 2 to measure the crankpin diameter. If the measured values are less than the specified limit, the
crankshaft must be replaced.

Crankshaft Journal and Diameter mm (in)
Standard Limit
4JA1T (L),
4JA1TC 59.921-59.928
(2.3591-2.3594) 59.91 (2.3586)
4JH1TC
69.917-69.932
(2.7526-2.7532) 69.91(2.7524)


Crankpin Diameter mm
(in)
Standard Limit
52.915 - 52.930
(2.0833 - 2.0839) 52.90 (2.083)



Crankshaft Journal and Crankpin Uneven W ear mm (in)
Standard Limit
0.05 (0.002) or less
0.08 (0.003)


Crankshaft Journal and Crankpin Diameter
If the clearance between the measured bearing inside diameter
and the crankshaft journal diameter exceeds the specified limit,
the bearing and/or the crankshaft must be replaced.

Crankshaft Journal and Bearing Clearance mm (in)
Standard Limit
0.032 - 0.077
(0.0013 - 0.0030) 0.110 (0.0043)



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ENGINE MECHANICAL 6A – 81

Connecting Rod Bearing Inside Diameter
1. Install the bearing to the connecting rod big end.
2. Tighten the bearing cap to the two step of anglar tightening method.

Connecting Rod Bearing Cap Bolt Torque
N·m (kg·m/Ib ft)
4JA1T (L), 4JA1TC 78-88 (8.0/57 – 9.0/65)
1st step ; 29.0–29.2 (3.00/22.0–3.01/22.2)4JH1TC
2nd step ; 45°-60 °
3. Use an inside dial indicator to measure the connecting rod
bearing inside diameter.



Crankpin and Bearing Clearance
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 Limit
4JA1T (L),
4JA1TC 0.029-0.066
(0.0011-0.0026) 0.100(0.0039)
4JH1TC
0.029-0.083
(0.0011-0.033) 0.100 (0.0039)



Clearance Measurements (With Plastigage)
Crankshaft Journal and Bearing Clearance
1. Clean the cylinder body, the journal bearing fitting surface, the bearing caps, and the bearings.
2. Install the bearings to the cylinder body.
3. Carefully place the crankshaft on the bearings.
4. Rotate the crankshaft approximately 30 ° to seat the
bearing.
5. Place the Plastigage (arrow) over the crankshaft journal across the full width of the bearing.
6. Install the bearing caps with the bearing.








7. Tighten the bearing caps to the specified torque.

Crankshaft Bearing Cap Bolt Torque mm (in)
167 (17/123)
Do not allow the crankshaft to turn during bearing cap
installation and tightening.
8. Remove the bearing cap.


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