M. CRANK SHAFT Clean and carry out visual inspection of crank shaft for the following: 1. Overheating of journals, this is indicated by bluish brown color. 2. Scoring marks on journals 3. Cracks, which should be checked on magnetic crack detector 4. Check crank shaft run out by supporting it on Vblock at 1st and 5th main bearing journals. 5. If run out exceeds permissible limits, straighten crank shaft in cold condition on press carefully. 6. Similarly check lateral and radial run outs of flywheel mounting flange. 7. Check crank shaft main bearing and crank pin journal dimension. 8. Record the readings in the format given at the end of this group. 9. If necessary, grind crank shaft main bearing and crank pin journals to next under-size. Maintain correct fillet radius for journals 10. Care must be taken during grinding to ensure 11. that width of journals is not increased. Should it be necessary to grind sides of 4th 12. main bearing journal, grind it to next undersize. Re-chamfer oil holes on journals to avoid 13. scoring of new bearing shells. Finish journals by lapping them with 320 grit 14. lapping cloth of suitable width. After grinding recheck main bearing and crank 15. pin journal dimensions. Also recheck run out of crank shaft. 16. Thoroughly clean crank shaft with standard 17. cleaning solution. Use wire brush for cleaning oil holes. Apply grease to all machined surfaces, if crank 18. shaft is to be stored. Crank shaft must always be stored in vertical position. Thoroughly clean main bearing caps and 19. corresponding machined surfaces of crankcase. Install main bearing caps without bearing 20. shells in their respective positions on crankcase. NOTE It is essential to recheck crankshaft for • cracks and balance after grinding. NOTE Ensure that the serial numbers on crank • case and main bearing caps are matching. Also caps are in order and notches forbearing shells are on same side. Diesel Engine Ph-2 (CAFÉ) 76
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