Yanmar 3TNV Series Service Manual

Contents

4. Disassembly, Inspection and Reassembly of Engines97(2) CrankshaftMainly check seizure and wear of the crankpins andjournals. Since the crankshaft gear is shrink-fitted,heat to 180 to 200 when extraction is necessary.(a) Shaft portion color checkAfter washing the crankshaft, inspect it by means ofcolor check or a magnaflux inspector. Replace it ifcracked or heavily damaged. Slight defects shall becorrected by grinding.(b) Crankshaft bendSupport the crankshaft journals at both ends withV-blocks. Use a dial gage and measure the runout atthe center journal while rotating the shaft to inspect thebend.Limit 0.02mm or less(c) Crankpin and journal measurementMeasure the outside diameter, roundness and taper ateach crankpin and journal.Correct by grinding if unevenly wear, roundnessexceeding the limit or insufficient outside diameter isfound. Replace if the defect is excessive.