TM 5-4310-393-14
a.
Reinstall the impeller/groove pulley in reverse order of removal.
4-14.4. VALVE HEAD ASSEMBLY, FIRST STAGE.
This task covers: A. Inspect B. Replace
Tools:
Materials/Parts
Valve Head Wrench,(P/N 004555)
O-ring (P/N N02169)
Torque Wrench (P/N 6006NMA)
Halo Carbon Grease, NSN 9150-00-754- 2760
Equipment Conditions:
Compressor Secured,
Air Pressure Purged From System
General 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 gasket
should 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 nonporous
Replace 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 be
replaced
f.
Inspect the valve seat (13). The sealing surface must be in good condition: devoid of pitting or
cracking 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 exceed
0.008" (0.2 mm).
h.
Check the tolerance of the inside diameter of the valve body (10). The valve body must not show any
groves 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 not
picked up on the next coil.
2.
Inspecting the Intake Valve.
NOTE
4-19
