TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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b. Value Rocker Arm Covers. Refer to paragraph 4-14. 6-30. Cleaning. a. Clean cylinder and associated parts, and remove heavy carbon deposits from combustion chamber with a scraper or blunt tool which will not nick or scratch the surface, Remove only the heavy carbon deposits. Surface need not be cleaned to a mirror finish. b. Clean carbon from fuel injector nozzle seat using nozzle carbon cutter - 4910-795-7958 as shown in figure 6-50. Figure 6-50. Clean ing carbon deposits from fuel injector nozzle seal using nozzle carbon cutter - 4910-795-7958. c. Soak cylinder in carbon removing com- pound to remove carbon and other foreign material from dome, valve ports, and the area between the top of the barrel and the head casting. 6-31. Inspection a. Valve Guides. Inspect valve guides (14 and 37, fig. B-4), for cracks, galling, erosion, or scuffing. Check guides for secure fit in cylinder. Check guides against limits specified in the overhaul standards (table 6-15). Note. Do not remove valve guides unless replacement is necessary. b. Valve Seat Inserts. Check valve seat inserts for secure fit in the cylinder (41, fig. B-4). In- serts must have tight fit. Inspect inserts for burned or pitted surfaces. Check valve seat contact by lightly bluing face of insert with Prussian blue - 8010-247-8706 and placing a new valve into position on valve insert. Rotate valve one-half turn on insert and check valve seat for Prussian blue contact. Valve seat must show perfect contact, as indicated by Prussian blue transfer, to qualify as a serviceable insert. Inserts that do not show perfect contact must be marked for repair. If inserts are cracked, loose, or damaged beyond repair, the cylinder must be replaced. If valve seat inserts can be made serviceable by grinding; repair as outlined in- paragraph 6-33a(2). Check the inserts against limits specified in overhaul standards (table 6- 15). c. Cylinder. Two types of cylinders have been used on the ADVS-1790 series engines. The latest type cylinder has a wall thickness in- creased by 0.030 inch to provide greater strength. These cylinders can be identified by a machined groove on the cylinder mounting flange periphery, refer to figure 6-51. 6-54