Service And Repair
Replacing the Air Purge Screw
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Figure 42. Installing Air Purge Screw Hitch Pin In The Retaining Position
12. If you removed the 2’’NPT plug to access the screw, get a new 2.234’’ ID x 0.139’’ wide O-ring from the
Hardware/Seal Kit and install it on the 2’’ NPT plug. Lubricate the O-ring with petroleum jelly and install the
plug into the leak detector port. Torque the plug to 20 - 50 ft-lbs (27 - 67 N•m).
If you removed a line leak detector to access the air purge screw, apply an adequate amount of fresh, UL clas-
sified for petroleum, non-setting thread sealant to the threads of the leak detection device and screw it into the
2’’ port. Torque the device until leak free.
13. Get a new check valve housing O-ring (2.609’’ ID x 0.139’’ wide) from the Hardware/Seal Kit. Lubricate the
O-ring with petroleum jelly and install it on the valve as shown in Figure 30 on page 35.
14. Screw the check valve into its port in the manifold. Torque the housing to 20 - 50 ft-lbs (27 - 67 N•m). Turn the
service screw all the way up (CCW). You will hear the check valve drop into position just before the screw is
all the way up. Replace the protective plug over the service screw and fully thread into place to ensure a good
seal.
15. Screw the air purge screw all the way down (cw), then back it off 2 - 3 turns counterclockwise.
The air purge screw is retained by the hitch pin to limit travel. Do not attempt to rotate
beyond 3 turns.
16. Turn the pump on and let it run for about 2 minutes to purge air from the manifold’s hydraulic cavities. While
the pump is still running, turn the air purge screw clockwise until it is completely closed.
17. Open the ball valve down line from the pump.
Push the hitch pin's up with one forefinger.
Note that the crimped leg of the pin is facing
down and the straight leg up.
While holding the pin up with one forefinger
position the gloved forefinger of the other hand
against the other end of the pin.
Push the end of the pin with the gloved
forefinger until it snaps into the retaining
position.
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WARNING