TM-9-2815-205-24 Technical Manual for M113 Engine 6V53 6V53T Download
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INSPECTION-ACCEPTANCE AND REJECTION CRITERIA Inspection of Crankshaft 1. Inspect gear teeth for evidence of scoring, pitting, and wear. If severely damaged or worn, replace gear. 2. Inspect crankshaft keyways for evidence of cracks or wear. Replace crankshaft if required. CAUTION Replace crankshaft when signs of excessive overheating appear since heat treatment has probably been destroyed. Remove ridges on crankshaft journals. If ridges are not removed, localized high unit pressures are placed on new bearing shells and short bearing life can result. 3. Inspect crankshaft journals for ridges and grooves. Remove ridges exceeding 0.0002 in. (0.005 mm). NOTE Replace crankshaft if journal ridges are greater than 0.001 in. (0.03 mm) in depth. 4. Remove crankshaft journal ridges by working crocus cloth, wet with fuel oil, around circumference of journals. If ridges are greater than 0.0005 in. (0.013 mm), first use 120 grit Emery cloth to clean up ridges, 240 grit Emery cloth for finishing and wet crocus cloth for polishing. 5. Inspect rear crankshaft at oil seal contact surface for evidence of rough or grooved condition. Clean up slight ridges on crankshaft oil seal contact surface with crocus cloth. If crankshaft cannot be cleaned up satisfactorily, reposition oil seal in flywheel housing. 6. Check crankshaft thrust surfaces for excessive wear or grooving. If only slightly worn, dress surfaces with an X-fine sharpening stone. NOTE To detect minute cracks use magnetic particle inspection method (reference ASTM E1444). Crankshaft failures are rare and when one cracks or breaks completely, make a thorough inspection for contributory factors. 7. Inspect crankshaft for fatigue cracks which start at an oil hole and follow journal surface at an angle of 45 degrees to axis. Reject crankshaft with cracks. 8. Inspect main bearing shells for bright spots on backs indicating movement in bearing caps or supports. Discard shells if this condition is present. CAUTION Install upper and lower bearing shells as a set. Do not replace one main bearing shell alone. Always install all new bearing shells with new crankshaft. NOTE Lower bearing shells, which carry the load, will normally show signs of distress before upper bearing shells. 9. Discard main bearings with signs of scoring, pitting, flaking, etching, overheating, or loss of overlay. END OF TASK TM 9-2815-205-24 0097 0097-5