To remove the first stage inlet valve, it is necessary to first remove the valve head.
Remove the tube nuts, tubes and ferrules from the tube connections (Figure 4-9, Item 16 and 18) to
the valve head (17) and the intake filter (not shown).
Inspect the O-ring (19). Replace It If it is damaged.
Unscrew and remove the socket head cap screws (15).
Lift the valve head (17) from the piston cylinder.
The valve plate (21) rests free on the piston cylinder; it is not spring operated.
Replacing the Valves.
Apply halo carbon grease to the O-ring.
Place the valve plate (Figure 4-9, Item 21) and O-ring (20) into the valve seat of the piston cylinder.
Install the discharge valve assembly (9) and the valve cover (6) with gasket (7) and O-ring (8).
Position the set screw (5). Do not tighten set screw.