Yanmar 3TNV Series Service Manual page 112

4. Disassembly, Inspection and Reassembly of Engines
(2) Crankshaft
Mainly check seizure and wear of the crankpins and
journals. Since the crankshaft gear is shrink-fitted,
heat to 180 to 200 when extraction is necessary.
(a) 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.
(b) 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 inspect the
bend.
Limit 0.02mm or less
(c) Crankpin and journal measurement
Measure the outside diameter, roundness and taper at
each crankpin and journal.
Correct by grinding if unevenly wear, roundness
exceeding the limit or insufficient outside diameter is
found. Replace if the defect is excessive.
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