45 4 DLT ENGINE Check crank case main bearing parent bore dimensions - Refer Figure 71 Since a slight clearance exists between main bearing cap dowel pins and corresponding dowel holes in crank case. It is possible that main bearing cap once removed may be installed off center, by which dimension of main bearing parent bore will be different in different direction. If there is a difference noticed in main bearing parent bore dimension, main bearing cap can be centralized by lightly tapping it with mallet in required direction after slightly loosening main bearing cap mounting bolts. If main bearing parent bore is slightly more than maximum permissible limits, it is possible to reclaim crank case Main bearing cap mating surface may be slightly faced after removing dowels. Parent bore should then be finished on a suitable line boring machine or with special reamer after fitting new dowels. Install new pairs of main bearing shells according to size of crank shaft main bearing journal diameter, making sure that securing lugs of bearing shells are properly seated in grooves of crank case and main bearing caps. Install main bearing caps with bearing shells in their respective position on crank case. Tighten main bearing cap mounting bolts to specified torque - Refer Figure 72. Measure main bearing bore - Refer Figure 73. IF MAIN BEARING PARENT BORE DIMENSION IS MAINTAINEDWITHIN SPECIFIED LIMITS, PROPER MAIN BEARING BORE DIMENSION IS AUTOMATICALLY ACHIEVED. However it must be physically measured and confirmed. Fig. 71 Fig. 72 Fig. 73
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