b. Use a hoist or other lifting device to support the
weight of the pump body (5). Remove the capscrews
(6, fig. 2-1), nuts (4), and lockwashers (5), that secure
Clean all parts in a well-ventilated area.
the feet of the pump body to the chassis frame.
Avoid inhalation of solvent fumes and
c. Remove the nuts (3, fig. 5-1) and lockwashers (4)
prolonged exposure of skin to cleaning
that secure the pump body (5) to the bearing housing;
solvent. Wash exposed skin thoroughly.
slide the pump body straight out to disengage it from the
Dry cleaning solvent (Fed. Spec. P-D-680)
remainder of the pump which is secured to the engine.
used to clean parts is potentially dangerous
d. Remove the capscrews (12), and lockwashers (13),
to personnel and property. Do not use near
that secure the assembled volute (18) and wear plate
open flame or excessive heat. Flash point of
(17) to the seal plate (29); remove the assembled parts.
solvent is 100 F. to 138 F. (38 C. to 59 C.).
e. Remove the cone nut (19) that secures the impeller
(20) to the impeller shaft. Use a puller to pull the
(2) Clean all parts with cleaning solvent (Fed.
impeller from the shaft and remove the key (21).
Spec. P-D-680) and wipe dry.
Temporarily install a plain hexagonal nut on the impeller
(3) Inspect the pump body for cracks, loose
shaft to protect the threads while pulling the impeller.
or damaged studs, and for damaged threads. Clean up
Remove the shims (22 and 23), seal spring (24), and
damaged threads with a thread die Replace any
seal rotating member (25) from the shaft.
damaged studs. Replace the housing if damaged
f. Remove the nuts (27) and lockwashers (28) that
secure the seal plate (29) to the bearing housing;
(4) Inspect the wear plate for wear, scoring,
remove the seal plate with the assembled seal
and distortion. If any damage is evident, replace the
stationary member (26). Remove the seal stationary
member from the seal plate.
(5) Inspect the volute for cracks, distortion,
internal scoring, and wear; replace if damaged.
(6) Inspect the impeller for cracked, chipped,
The seal members are not replaceable
worn or broken vanes, damaged or distorted bore or
individually. When replacing the seal, be
keyway, and other damage; replace a defective
sure to replace all parts that are provided in
the seal kit.
c. Reassembly. Reassemble the pump by reversing
the disassembly sequence. Refer to figure 5-1. Note
g. Install the seal stationary member (26) into the seal
plate (29); install the seal plate on the bearing housing
(1) Press the seal stationary member (26)
with nuts (27) and lockwashers (28).
into seal plate (29) before installing the plate. Lubricate
h. Lubricate the inside diameter of the seal rotating
the impeller shaft lightly with oil and slide the seal
member (25). Install the rotating member onto the
rotating member (25) and spring into place on the shaft.
shaft, and install the seal spring (24). Take care to
(2) If the same impeller (20) and wear plate
prevent damage to the interior of the seal member
(17) are reassembled and no clearance change is
during assembly, or premature failure will result. Also
indicated, use shims (22 and 23) of the same thickness
use extreme care to prevent damage to the contact
as those removed. If a new impeller and/or wear plate
faces, both the stationary and rotating seal members.
is installed, determine the shim thickness required to
i. When installing the impeller (20), be sure you install
obtain a clearance of 0.010 to 0.020 inch (0.025 to
shims (22 and 23) of the same thickness as those
0.050 cm) between the impeller and wear plate as
j. Reassemble the remainder of the pump by reversing
(a) Install impeller (20) on shaft without
the disassembly procedure.
When installing the
shims. Be sure that impeller is seated firmly against the
impeller nut (19) onto the impeller shaft, tighten the nut
to 95 to 110 foot-pounds (13,138 to 15.213 kgm) torque.
(b) Install volute (18) with wear plate (17)
Block the impeller with a block of wood to prevent its
assembled, and secure with screws (12) and
rotation when you install the nut (19).
(c) Insert a feeler gage into the front
5-3. Centrifugal Pump Overhaul
opening of the volute and measure from the face of the
a. Disassembly. Disassemble the pump following the
impeller (20) to the face of the wear plate (17).
sequence of index numbers in figure 5-1.
(d) Select shims (22 and 23) to equal the
b. Cleaning and Inspection.
dimension obtained less 0.010 to 0.020 inch (0.025 to
(1) Discard and replace all seals, gaskets,
0.050 cm) for clearance.