TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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g. Valve Rocker Arm Covers. (1) Repair or replace damaged parts. Welding is permissible on the two valve rocker arm shaft plug bosses on the outside of the cover. Welding in other areas of the cover is not per- missible. Refer to paragraph 6-4c for general welding instructions, and paragraph (e), below. (a) Replace cylinder assembly when valve rocker arm cover is cracked (except at the rocket arm shaft plug boss which can be welded), or has deep scratches or nicks on the mating surface or camshaft bearing bore surface. Replace cylinder when cover damage cannot be removed by polishing with crocus cloth dipped in dry-cleaning solvent or mineral spirits paint thinner. (b) Replace cylinder assembly when valve rocker cover does not conform to limits specified in the overhaul standards (table 6-15). (c) Replace damaged screw thread inserts as instructed in paragraph 6-5. (d) Replace cracked adjusting cover plates. Remove minor nicks, burs, or scratches from mating surface with crocus cloth dipped in dry-cleaning solvent or mineral spirits paint thinner. (e) Covers that have been repaired by welding must meet the requirements specified in figure 6-64. Figure 6-64. Valve rocker arm cover welding standards. AT 311 h. Valve Rocker Arm. (Refer to fig. B-4) (1) Replace valve rocker arms (33 and 34) when cracked or worn or if the bushing-type bearings are damaged. (2) Replace damaged valve rocker arm roller and bushing. (3) Replace adjusting screw (36) when threads are stripped or damaged or when screw binds in rocker arm. Replace adjusting screw when swivel pad does not rotate freely on screw. i. Valve Rocker Arm Shaft Assemblies. (Refer to fig. B-4) 77 (1) Replace cracked or deeply scored rocker arm shaft assemblies (22 and 35). (2) Replace rocker arm shafts that do not conform to limits specified in the overhaul standards (table 6-15). Valve, Springs, Spring Retainers and Rotors. (Refer to fig. B-4) (1) Valves. (a) Discard warped valves (11 and 12) or valves which do not conform to limits specified in repair and, rebuild standards (table 6-1 5). Discard valves having badly pitted or burned 6-73