TM-9-2815-220-34 Direct Support Manual for AVDS-1790-2C and AVDS-1790-2D Engines Download
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Figure 3·152. Checking torque <1/ 111ai11 bearing cop JtJ. (3) Spread a thin coat of Prussian blue Part No. MIL·P-30501, over steel backs of upper and lower main sleeve bearing halves to show the sleeve bearing contact surface with the main bearing bore in crank- case. Install bearings in their original lation in crankcase and main bearing caps. (4) Check clearance between upper bearing flange and crankcase. Install upper main thrust sleeve bearing into No. 4 main bearing seat of crank· case. Measure clearance between bearing flange and crankcase using feler gage (fig. 3·15). Clearance should be 0.4 to 0.8 inch. F1ure 3-153. Checking clearae between upp er main thrt beoring flange and c1aukc. TM 9-2815-220-34 (5) Check clearance between the lower main thrust bearing flange and thrust bearing cap in the same manner as shown in figure 3-153. (6) Apply a light coating of engine oil to the ends of the seven main bearing caps with sleeve bearing halves installed. Using crankcase spreading tꝏl Part No. 87S61, as shown in figure 3-130, install the bearing caps with bearing halves in their proper lations in the crankcase, according to the lation number stamped on the crankcase and cap. The side of the bearing cap marked" FLY END" must face the rear of the crankcase. (7) Apply a small amount of OE 30 engine oil or GAA grease 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. (8) Place a surface plate and dial indicator 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 20 pound- inches. Alternately tighten all four nuts on each main bearing to a torque of 7-825 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. Nor- mal stud stretch is 0.019 to 0.022 in. Apply additional torque to obtain a stud stretch of 0.019 to 0.022. Do not exceed 0.024. If any stud has stretched more than 0.024 in. at 7 pound-inches torque, it must be replaced. Refer to table 3-2 when replacing studs. (9) Install the 14 engine crankcase rods (13, fig. 3- 149) in the holes provided through the crankcase and main bearing caps. Equalize the extension of the threaded portions of the rs on each side of the crankcase. Apply a small amount of OE 30 engine oil or GAA grease to the threaded portions of each rod. Install a plate washer and a 9/16 slotted nut on each end of the rs (12 and 11, fig. 3-149). (10) Starting at the main thrust bearing cap, with aid of an assistant to hold the nuts 011 the op- posite side of crankcase. alternately tighten all main bearing cap engine crankcase rod nuts to 640 pound- inches torque. (11) Check the inside diameter of the main bearings with a dial bore indicator as shown in figure 3-154 against the limits specified in repair standard (table 3-1). 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. surfaces as indicated by Prussian transfer. Replace bearings that do not make 75 percent contact with crankcase bearing bores. Repeat dial bore check of new bearings installed. 3-71