TM 5-4310-393-14a.Reinstall the impeller/groove pulley in reverse order of removal.4-14.4. VALVE HEAD ASSEMBLY, FIRST STAGE.This task covers: A. Inspect B. ReplaceTools:Materials/PartsValve Head Wrench,(P/N 004555)O-ring (P/N N02169)Torque Wrench (P/N 6006NMA)Halo Carbon Grease, NSN 9150-00-754- 2760Equipment Conditions:Compressor Secured,Air Pressure Purged From SystemGeneral Instructions. Observe the following instructions for all valve maintenance.Always replace valves as a complete set.Observe the correct sequence when reassembling.Remove and check valves in accordance with PMCS schedules.Tighten the screws and nuts for the valve heads and cylinders equally and in a diagonal sequence.Be sure that valves are cold before tightening Refer to Appendix E for torque requirements.A.Inspect.1.Inspecting the First Stage Discharge Valve.a.Remove the plain cap nut (Figure 4-9, Item 3) and the gasket (4) and inspect the gasket. The gasketshould be replaced if it Is damaged.b.Unscrew and remove the socket set screw (5) and the discharge valve cover (6).c.Remove the disc spring (7) and the O-ring (8). The O-ring should be undamaged and nonporousReplace it if necessary.d.Extract the discharge valve assembly (9).e.Discard the valve gasket (14) and replace it with a new one. The valve gasket must always bereplacedf.Inspect the valve seat (13). The sealing surface must be in good condition: devoid of pitting orcracking The maximum valve seat width is 0.039" (1.0 mm).g.Clean and inspect the valve plate (12) The maximum acceptable groove depth must not exceed0.008" (0.2 mm).h.Check the tolerance of the inside diameter of the valve body (10). The valve body must not show anygroves at ID 0.669"-0 673" (17.0-17.1mm).i.The valve spring (11) Is serviceable again if it shows no outside scuffing and the spring ends have notpicked up on the next coil.2.Inspecting the Intake Valve.NOTE4-19
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