TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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(c) Fine scratches on sleeve bearing are not cause for rejection. Pitting or any other form of destruction to the bearing surface is cause for rejection. Replace bearings showing raised metal at edges of scratches. (d) Minute pieces of metal and dirt particles embedded in bearing surfaces are not cause for rejection. Note. Do not attempt to remove such particles. However, if a concentration of em- bedded particles affects five percent of the surface, replace the bearing. (4) Stud (tie rod) torque and main bearing bore inspection. Note. Main sleeve bearing halves should be their original location in crankcase and main bearing caps. (d) Check clearance between upper bearing flange and crankcase as shown in figure 6-11. (e) Check clearance between the lower main thrust bearing flange and thrust bearing cap in the same manner as shown in figure 6-11. installed in their original location when they are to be re-used. Use new bearings when a visual inspection indicates bearings are unserviceable. Use only new or serviceable bearings for main bearing-bore check. (a) Refer to figure 6-8 for instructions to install crankcase on engine overhaul stand. (b) Check main bearing cap stud torque using a torque wrench as shown in figure 6-10. Torque on studs must be 450 pound-inches. Studs that do not tighten to specified torque must be removed for further inspection. Refer to table 6-3 when replacing studs. Note. Never tighten main bearing studs above recommended torque. 1. Install upper main thrust sleeve bearing (A) into No. 4 main bearing seat of crankcase. 2. Measure clearance between bearing flange and crank- case using feeler gage (B). Clearance should be 0.0040 to 0.0080-inch. Figure 6-11. Checking clearance between upper main thrust bearing flange and crankcase. Figure 6-10. Checking torque of main bearing cap studs. (c) Spread a thin coat of Prussian blue, FSN 8010-247-8706, over steel backs of upper and lower main sleeve bearing halves to show the sleeve bearing contact surface with the main bearing bore in crankcase. Install bearings in (f) Apply a light coating of engine oil, Military Specification MIL-L-45199, to the ends of the seven main bearing caps with sleeve bearing halves installed. Using crankcase spreading tool - 5120-575-7767 as shown in figure 5-174 install the bearing caps with bearing halves in their proper locations in the crankcase. according to the location number stamped on the crankcase and cap. The side of the bearing cap marked “FLY END” must face the rear of the crankcase. (g) Apply a small amount of antiseize 6-16