9
Repair Instructions - P420A-5100/P422-5100/P423-5100 and P425-5100
Note: Always take time to lubricate all metal and nonmetal parts with a light film of oil before reassembly. This step
will ensure proper fit, at the same time protecting the pump nonmetal parts (i.e., the elastomers) from cutting and
scoring.
1) With a socket wrench,
remove the three dis-
charge valve plugs and
three inlet valve plugs
(32). Inspect the o-ring
(33) for wear and replace
if damaged.
2) Using needle nose pli-
ers, remove the inlet and
discharge valve assem-
blies (27A). Note: It
may become neccesary
to remove the valve seat
(27) from the valve casing
using a slidehammer.
3) By inserting a small screw
driver between the valve
seat (27) and the valve
spring retainer (30), the
valve assembly can be
separated.
4) Remove the O-ring (31).
Inspect all parts for wear
and replace as necessary.
Apply one drop of loctite
243 to the valve plugs (32)
and tighten to 107 ft.-lbs.
(145 NM).
5) Use a 8mm allen wrench
to remove the 8 socket
head cap screws (34).
Carefully slide the valve
casing (26) out over the
plungers.
6) Remove seal adapters
(20) and weep return rings
(25) from the valve casing.
7) Remove the pressure
rings (24) and v-sleeves
(23 - Note: P422 & P423
pumps have a support
ring) from the valve cas-
ing (26).
8) Remove the weep grooved
seal (23 or 23B) together
with pressure ring (24 -
P420 and P425 only) out
of the seal case (20).
Check O-rings (21).
IMPORTANT!
The grooved
seal (23) on the high-pressure
side is to be fitted carefully into
the valve casing (26) using a
screwdriver. Under no circum-
stances must the seal surface
in the valve casing or the seal
lip be damaged.
