8. Butt clearance of piston ring should be measured in unworn portion of cylinder bore 9. In case of any piston ring with any one of this defect, complete ring set should be replaced. When cylinder bores are re-bored or honed, 10. pistons and rings of appropriate size should be used. Piston size grade is stamped on piston crown. Install piston rings in their respective position 11. on piston using ring expander. Stagger piston rings gaps such that they are 12. 120°apart (with butt gap not in line with piston pin) CRANKSHAFT Clean and carry out visual inspection of crank shaft for the following: 1. Overheating of journals, this is indicated by bluish brown colour. 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 3rd 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 crankshaft with standard 17. cleaning solution. Use wire brush for cleaning oil holes Diesel Engine Ph-2 (CAFÉ) 162
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