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TM 9-4110-257-14
WARNING
Dangerous pressure can remain trapped in compressor cylinder head. Removal of cylinder
head screws prior to relieving pressure can result in personal injury.
NOTE
The following procedures apply to both pairs of cylinders.
(4)
Loosen but do not remove eight screws (7). If cylinder head (8) is not loose, tap with lightweight hammer
to loosen.
NOTE
Valve plate, suction valves, position springs, and dowel pins may come off
when removing cylinder head.
(5)
Remove eight screws (7), cylinder head (8), and cylinder head gasket (9). Discard cylinder head gasket.
(6)
Remove four screws (10), lock washers (11), two discharge valve stops (12), and discharge valves (13).
Discard lock washers and discharge valves.
(7)
Install two screws (10), without lock washers (11), into the outermost discharge valves (13) mounting holes to
act as jackscrews to release valve plate (14).
(8)
Remove valve plate (14), valve plate gasket (15) two suction valves (16), position springs (17), and four
dowel pins (18). Discard valve plate gasket and suction valves.
(9)
Examine compressor (3) cylinder walls for any scoring or excessive wear indicated by a groove at top of
piston (19) travel. Replace compressor if scored or excessively worn.
(10)
Press on top of highest piston (19). When pushed down, the piston should have some resistance and the
other piston should move. Repeat for other piston when at highest point. If either piston was loose or did not
cause the other one to move, replace compressor.
(11)
If no failure was indicated, remove any gasket material from all machined gasket surfaces and install four
dowel pins (18), two position springs (17) contacting on the ends and bowed out in the middle, new suction
valves (16), new valve plate gasket (15), and valve plate (14).
(12)
Check that suction valves (16) do not bind on valve plate gasket (15) by gently pushing on suction valve
through intake hole in valve plate (14). Adjust valve plate gasket as necessary to prevent suction valve
binding.
(13)
Install two new discharge valves (13), discharge valve stops (12), four new lock washers (11), screws (10),
new cylinder head gasket (9), cylinder head (8), and eight screws (7). Torque screws to between 40 and 55 -
lb (54 and 75 Nm).
(14)
Install suction screen (6). Carefully align service valve (2) being careful not to bend or kink tubing (4). Install
new service valve gasket (5) and two bolts (1). Torque bolts to between 15 and 25 ft-lb (20 and 34 Nm).
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