Troubleshooting guide

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Displacement Pump Service
NOTE: To replace the throat packing, which is in -
cluded in Repair Kit 237–498, refer to the Air Motor
and Throat Packing Repair section on page 13.
4. Use a strap wrench on the displacement cylinder
(16) to screw it out of the air motor base (52).
Carefully inspect the smooth inner surface of the
cylinder for scoring or irregular surfaces. Such
damage causes premature packing wear and leak -
ing, so replace the part if damaged.
5. Loosen the locknut (2), unscrew the piston (1 1)
from the connecting rod (15), and disassemble the
piston. See Fig. 6.
6. Clean and inspect the parts and replace any that
are worn or damaged. Be sure to check the o-ring
(9) in the motor base (52).
7. Grease the new piston packings and reassemble
the piston as shown in Fig. 6.
8. Reinstall the piston (1 1) on the connecting rod
(15), allowing 0.2 in. (5 mm) of free travel between
the steel ball (3) and the end of the connecting rod
before tightening the locknut (2). See Fig. 6.
NOTE: A guide collar is required for installing the pis -
ton in the displacement cylinder . Guide Collar T ool,
168–085, is available, or make a collar using shim
stock having a 0.016 in. (0.41 mm) maximum thick -
ness.
9.
Grease the inside top of the displacement cylinder
(16). Compress the leather cup packings with the
guide collar tool (R) and work the displacement
cylinder onto the lower packing with a turning mo -
tion. See Fig. 7. Remove the guide collar tool,
push the displacement cylinder up, and screw it
firmly into the air motor base.
10. If the ground wire was disconnected before servic -
ing, be sure to reconnect it before regular opera -
tion of the pump.
Fig. 7
15
11
R
16
04123