16
G25-991-2400A
H/G-25 Service (Hydraulic End)
NOTE: The numbers in parentheses are the Ref. Nos. on
the illustrations in the Parts Manual.
CAUTION: Do not disassemble the hydraulic end unless
you are a skilled mechanic. For assistance, contact Wanner
Engineering (TEL 612-332-5681 or FAX 612-332-6937) or
the distributor in your area.
CAUTION: The four bolts (26) that screw through the back
of the housing into the cylinder casting (25) hold the casting
to the pump housing. Do not remove them except when
repairing the hydraulic end.
NOTE: The following service procedures refer several
times to the Wanner Tool Kit. We strongly urge you not to
try to repair the hydraulic end of the pump without using
the tools in this kit (available from Wanner or your local
distributor).
1. Remove Pump Housing
a. Remove the head of the pump, and the diaphragms, as
outlined in the Fluid-End Service Section.
b. Drain the oil from the pump housing by removing the
drain plug (34).
c. Set the hydraulic end of the pump face-down on the
cylinder casting (25).
d. Check the shaft for sharp burrs. Smooth any burrs,
to prevent scarring the housing seals (64) when you
disassemble the pump.
e. Remove the bolts (26) that secure the housing to the
cylinder casting. The piston return springs (50) will force
the cylinder casting and housing apart.
f. Lift off the housing (30).
g. Inspect the cam and bearings (62), and the bearing race
in the rear of the housing. If the bearings are pitted or
binding, or if the housing race is worn, contact Wanner
Engineering.
2. Disassemble Pistons
a. With the pump housing removed (see above), turn the
unit over and set it on a flat surface, piston side down.
b. With diaphragms removed (see the Fluid-End Service
Section), reinsert a follower screw (19) into the hole
in one of the valve plungers (54). Tap the screw lightly
with a hammer; the plunger (23) should slip off the valve
plunger (54).
The hydraulic piston assembly (50-59) can now be
disassembled. Inspect all parts, and replace all O-rings
and any other parts that are worn or damaged.
c. Repeat step b for the remaining pistons.
NOTE: When you reassemble the hydraulic piston,
use new plungers (23). They are press-fit onto the
valve plungers (54) and are generally not reusable.
3. Reassemble Pistons
a. Drop a ball (58) into each opening in the bottom of a
piston assembly (59).
b. Insert a retaining washer (57) and O-ring (56) to hold the
ball in place.
c. Insert a valve plunger (54) into a valve cylinder (55).
Slide a spring (53) over the plunger, inside the valve
cylinder.
d. Insert an O-ring (52) into a spring retainer (51).
e. Install two O-rings (52) on the valve cylinder (55).
f. Slide the assembled valve cylinder, plunger, and spring
(53-55) into the spring retainer (51).
g. Install an O-ring (56) on the spring retainer (51).
h. Slide the complete cylinder-and-retainer assembly (51-
56) into the piston assembly (59).
i. Insert a return spring (50) into the piston assembly.
j. Repeat the above procedure for the other two pistons.
4. Reassemble Pump Housing
and Cylinder Housing
NOTE: Inspect the shaft seals (64) before continuing.
If they look damaged in any way, replace them (remove
by pounding them out from inside the pump housing).
Both seals should be replaced at the same time. Clean
the seal bore in the housing, using emery cloth or
ScotchBrite™.
a. Place the cylinder housing (25) face-down on a flat
surface.
b. Insert the assembled pistons (50-59) into the cylinder
housing.
c. Note the location of the outer ring of holes in the cylinder
casting and in the pump housing flange — in particular,
the holes where bolts (26) will be installed. Screw
threaded studs (from the Wanner Tool Kit) into two of the
four threaded holes in the cylinder housing. Use opposite
holes.
d. Stand the camshaft assembly (62) on the cylinder
housing (25).
CAUTION: The pilot bearing MUST be properly nested
in the bearing race during assembly. If misaligned,
the bearing will be damaged and the pump will fail
within the first hours of operation.
e. Using grease to retain it, install the O-ring (65) and
slide the housing (30) down over the shaft and onto the
threaded studs (from step c). Be sure the holes in the
housing and the cylinder housing are properly aligned.
f. Install washers (6) and nuts (31) on the threaded studs,
but don’t tighten yet. You may want to insert two or more
bolts (5) into the unthreaded holes of the housing and
cylinder housing to help align the parts.
To Next Page
Loading...
