Isuzu KB P190. Manual — part 220

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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