Komatsu 4D98 Series Shop Manual page 70

4. Engine Body
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If the limit is exceeded or any surface defect is found, repair by boring and honing. Use an
oversized piston (and new piston rings) as required.
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Oversized piston (0.25 mm)
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Code No. 1 Standard (mm) 1
4TNE94 129900-22700 $94.250
4TNE98 129902-22700 $98.250
4TNE106 123900-22700 $106.250
1 4TNE106T / 123901-22700
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$106.250
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Cylinder boring dimension
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Piston ring for oversized (0.25 mm)
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1 Boring dimension (mm) 1
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1 Piston ring code No.(Assy) 1
(5.2) Crankshaft
Mainly check seizure and wear of the
crankpins and journals. Since the
crankshaft gear is shrink-fitted, heat to
180 to 200°C when extraction is neces-
sary.
Shaft portion color check
After washing the crankshaft, inspect it
by means of color check or a magnaflux
inspector. Replace it if cracked or
heavily damaged. Slight defects shall
be corrected by grinding.
Crankshaft bend
Support the crankshaft journals at both
ends with V-blocks. Use a dial gage
and measure the runout at the center
journal while rotating the shaft to in-
spect the bend.
Limit 0.02 mm or less
1 4TNE106 (T) ( 129300-22950
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4TNE94
129901-22950
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4TNE98 129903-22950
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Inspection bv color chec
V-block
V-block
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Crankshaft
bend measurement
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