TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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faces. Discard valves having badly pitted, scored, scratched stems or locking grooves. (b) Reface slightly pitted or burned valves that do not seat perfectly to limits specified in figure 6-63. Discard valves that cannot be refaced to these limits. (c) Check valve length from seat contact to tip of stem after grinding, as shown in figure 6- 63. Discard valve if length is not within limits specified (fig. 6-63). (2) Valve springs. Replace springs (16, 17, and 18) when worn, cracked, or otherwise dam aged. Replace springs that do not conform to limits specified in overhaul standards (table 6- 15). (3) Valve spring retainers, valve rotors, and valve locks. (Refer to fig. B-4) (a) Replace upper intake and exhaust valve spring retainers (19 and 38) and valve spring seat (15) when cracked or worn. (b) Replace valve rotors (40) when inner section does not rotate freely or when assembly is worn or cracked. (c) Replace valve locks (20) when worn or cracked. 6-34. Assembly a. Cylinders. (Refer to fig. B-4) (1) Install intake valve (12) and exhaust valve (11) in their respective guides in cylinder (41). Hold valves in position and place the cylinder on valve removing and inserting stand - 4910-554-1317 following instructions which accompany figure 6-65. 1. Position the valve lifter assembly - 5120-678-5285 over the valve springs and retainers (A) and secure in position with four 5 / 16 x 1-3/8 bolts and 5 / 16-in. flat washers. 2. Compress valve springs and retainers with screws (B) and install two valve locks (20) in the groove of each valve stem. Release valve spring compression. Remove valve lifter assembly - 5120-678-5285 from cylinder and remove cylinder from stand. Figure 6-65. Co repressing valve springs using valve lifter assembly-5120-678-5285. (2) Install the exhaust valve rotor (40), outer, intermediate, and inner springs (16, 17, and 18), and upper exhaust valve spring retainer (38) over the exhaust valve stem as shown in figure 6-49. Install the lower intake valve spring seat (15), outer, intermediate, and inner springs (16, 17, and 18), and upper intake valve spring retainer (19) over the intake valve stem in the same manner. Compress valve springs and install valve locks following instructions which accompany figure 6-65. b. Valve Rocker Arm Covers. Refer to paragraph 4-14. 6-74