NMWR-9-2815-220 Overhaul Manual for M60 M88 Engine AVDS-1790-2CA, AVDS-1790-2DA, AVDS-1790-2DR Download
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NMWR 9-2815-220 CYLINDER ASSEMBLY OVERHAUL—Continued 0012 00 INSPECTION – Continued (c) Valve seat inserts. Inspect inserts for pitted surfaces. If inserts are cracked, loose, or damaged beyond repair, the cylinder must be replaced. Check valve seat contact by lightly bluing face of a new valve with Prussian blue, A-A-3108 and placing 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 contact all around (360°), as indicated by Prussian blue transfer, to qualify as a serviceable insert. Inserts that do not show all around contact must be marked for repair. (d) Fuel injector nozzle seat. Inspect the fuel injector nozzle seat for cracks, galling, erosion, scuffing, hard carbon, or burning. (e) Screw thread inserts. Refer to WP 0005 00 when inspecting cylinder head assembly screw thread inserts. (f) Fins. Allowable missing fin area on the cylinder head is shown in Figure 4. (g) Mounting flange and dowel holes. Inspect dowel holes in the mounting flange for wear, nicks, and burrs. Also inspect for cracks in the mounting flange. 3. Valve rocker arm covers and associated parts inspection. (a) Valve rocker arm cover. Inspect valve rocker support cover for cracks, particularly in area of rocker arm shaft plugs, using dye penetrant method. Check valve adjusting access cover for cracks, and for warpage. (b) Valve rocker arms. Inspect valve rocker arms for cracks using a magnifying glass (five power magnification minimum) under a strong light. Inspect the bushing-type bearing sleeves in the rocker arms for scoring and looseness. Measure inside diameter of the bearing sleeves. Replace bearing sleeves that do not meet limits. Inspect valve rocker arm rollers for scuff or score marks and looseness on hub. Rotate roller and check clearance between roller and hub by mounting rocker arm securely in a soft-jawed vise. Set a dial indicator against the contact surface of the roller and move roller through the extremes of its travel while checking the reading on the dial indicator. Limits should be 0.0055 in. (0.1397 mm) maximum. Inspect adjusting screw for stripped or damaged threads by turning screw in and out of rocker arms. Screw must turn freely. Check swivel pad and adjusting screw for free rotation. Mark damaged parts for replacement. (c) Valve rocker arm shafts. Check valve rocker arm shaft for cracks using magnetic particle method. Also check for scuffing, scores, and metal pickup or plugged oil passages. Measure outside diameter for wear. 0012 00-4 Change 1