54 4 DLT ENGINE If run out exceeds permissible limits, straighten crank shaft in cold condition on press carefully. Similarly check lateral and radial run outs of flywheel mounting flange. Check crank shaft main bearing and crank pin journal dimension. If necessary, grind crank shaft main bearing and crank pin journal to next under size. MAINTAIN CORRECT FILLET RADII FOR JOURNALS. Caremust be taken during grinding to ensure that width of journals is not increased. Should it be necessary to grind sides of 4th main bearing journals, grind it to next over size. Re-chamfer oil holes on journals to avoid scoring of new bearing shells. Finish journals by lapping them with 320 grit lapping cloth of suitable width. After grinding recheck main bearing and crank pin journal dimensions. Also recheck run out of crank shaft. Thoroughly clean crank shaft with kerosene. Use wire brush for cleaning oil holes. IT IS ADVISABLE TO RECHECK CRANK SHAFT FOR CRACKS AND BALANCE AFTER GRINDING. Apply grease to all machined surface, if crank shaft is to be stored. Crank shaft must always be stored in vertical position. CAM SHAFT Carry out visual inspection of cam shaft for: - Over heating of journals, which is indicated by bluish/brown colour. - Deep scoring marks on journals and cam lobes - Cracks, which should be checked on a magnetic crack detector. Check hardness of cam shaft journals and cam lobes. It should be 48-54 HRC. Check cam shaft run out at 2nd, 3rd and 4th journal by supporting it onV-block at 1st and 5th journal.Refer Figure 93 CONNECTINGRODS Inspect connecting rod small end bush and if necessary remove it. Check connecting rod small end parent bore dimension. Refer Figure 94 If necessary machine Connecting rod small end parent bore to next over size. ENSURE THAT CONNECTING ROD BIG END AND SMALL END AXES ARE PARALLEL TO EACH OTHER WITHIN SPECIFIED LIMITS Fig. 93 Fig. 94
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