TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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compound, FSN 9150-663-1770, to the threaded area of each main bearing cap stud. Install a plate washer on each pair of main bearing studs. Install a slotted nut on each main bearing stud but do not tighten nuts at this time. (h) Place a surface plate and dial in- dicator gage on crankcase flange with gage indicator resting on end of stud. Measure and record height of each stud. Torque tighten main bearing stud nuts to 500 pound-inches. Alter- nately tighten all four nuts on each main bearing to a torque of 700-825 pound-inches. Measure the height of each stud after final torque. The difference between the stud height before and after torque tightening, indicates stud stretch. Normal stud stretch is 0.010 to 0.022-in. If any stud has stretched more than 0.024-in. at 700 pound-inches torque, it must be replaced. Refer to table 6-3 when replacing studs. (i) Install the 14 crankcase tie rods in the holes provided through the crankcase and main bearing caps. Equalize the extension of the threaded portions of the tie rods on each side of the crankcase. Apply a small amount of antiseize compound, FSN 9150-663-1770, to the threaded portions of each tie rod. Install a plate washer and a 9 / 16 slotted nut on each end of the tie rods. (j) Starting at the main thrust bearing cap, with aid of an assistant to hold the nuts on the opposite side of crankcase, alternately tighten all main bearing cap tie rod nuts to 640 pound-inches torque. (k) Check the inside diameter of the main bearings with a dial bore indicator as shown in figure 6-12 against the limits specified in overhaul standards (table 6-2). Replace bearings which do not meet these requirements. New bearings must also be dial bore checked. Remove the main bearing caps and bearing halves from the crankcase and check contact surface as indicated by Prussian blue, FSN 8010-847- 8706 transfer. Replace bearings that do not make 75 percent contact with crankcase bearing bores. Repeat dial bore check of new bearings installed. Figure 6-12. Checking inside diameter of main bearings. 6-17