NANO

ENGINE 273 MPFI 133 ENGINE Crank Shaft and Main Bearing Clean and carry out visual inspection of crank shaft for following: • Overheating of journals, this is indicated by bluish brown colour • Scoring marks on journals • Cracks, which should be checked on magnetic crack detector. CAUTION Crankshaft fillet grooves should not be scraped, polished, ground even in regrinding operation. The grooves should remain untouched throughout the life of crankshaft after factory installation. • Check crank shaft run out by supporting it on V- block. CRANK SHAFT RUNOUT STANDARDVALUE WEAR LIMIT 0.02 mm 0.04 mm • 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 journals to next undersize. • Care must be taken during grinding to ensure that width of journals is not increased. • Should it be necessary to grind the main bearing journal, grind it to next under size. • Re-chamfer oil holes on journals to avoid scoring of new bearing shells. • Finish journals by lapping themwith 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 essential to recheck crank shaft for cracks and balance after grinding. • Apply grease to all machined surfaces, if crank shaft is to be stored. Crank shaft must always be stored in vertical position. • Crankshaft thrust play Measure this play with crankshaft set in the cylinder block in the normal manner, that is, with the thrust bearing fitted and the bearing caps installed. Tighten bearing cap bolts to specified torque. Use a dial gauge to read the displacement in axial (thrust) direction of the crankshaft. If the limit is exceeded, replace thrust bearing with new standard one or oversize one to obtain standard thrust play. CRANK SHAFT THRUST PLAY STANDARDVALUE WEAR LIMIT 0.06 to 0.245 mm 0.3 mm SR. ITEM STD. VALUE LIMIT 1. Thickness of Oversize (0.05) crankshaft 2.5 to thrust bearing 2.55 mm 2.575 mm 2. Main bearing 0.020 to clearance 0.054 mm 2.575 mm 3. Main bearing Undersize (0.05) journal 44.989 to 44.739 diameter 45.000 mm 44.750 mm • Inspect the bearing shells for signs of fusion, pitting, burn or flaking and observe the contact pattern. Defective shells must be replaced. CAUTION The journal bearing shells are not meant to be repaired by scraping or grinding with sandpaper or by any machining.