SERVICING THE VALVE ASSEMBLIES
Disassembly
1. Remove the two (2), four (4) or eight (8) Hex Flange
Nuts securing the Discharge Manifold to the crankcase
of the pump.
2. Support the Discharge Manifold and tap from the
backside with soft mallet. Gradually work free from
Cylinders.
3. Valve assemblies will remain in the Manifold. Pump
models with the o-ring groove on the outside of the
valve seat require the assistance of a Reverse Pliers
Tool to remove the valve seat. The Valve, Spring and
Retainer will then fall out when the Manifold is inverted.
Pump models without the o-ring groove on the outside
of the Valve Seat permit the Seat, Valve, Spring and
Retainer all to fall out when Manifold is inverted.
Reassembly
1. Examine Retainer for wear and replace as needed.
Place Retainer in manifold chamber with nylon tab
down.
2. Examine Spring for fatigue and replace as needed.
Insert Spring into center of Retainer.
3. Inspect the Valves for wear, ridges or pitting and
replace as needed.
NOTE: Seating side of Flat Valves may be lapped on
flat surface using 240 grit paper. Quiet Valves due
to their shape must be replaced. Insert Valve over
Spring with dimpled side up.
NOTE: Do not mix Quiet Valve and Flat Valve
Assemblies.
4. Examine Valve Seats for wear, pitting or grooves. Lap
the Flat Valve Seats with 240 grit paper or replace if
evidence of excessive wear. Quiet Valve Seats must
be replaced if worn. Install Seats with dishside down.
5. Examine O-Rings and Back-up-Rings on the Valve
Seat if used and replace if worn. Always lubricate
O-Rings for ease of installation and to avoid damage.
NOTE: First install O-Ring in groove on seat
towards seating surface, then Back-up-Ring.
NOTE: Models without outer groove on seat require
the O-Ring to be placed on lip of retainer.
NOTE: On Model 390, examine O-Rings on
Discharge Valve Adapter and replace if cut or worn.
Lubricate O.D. of Adapter O-Rings and press
Adapter into Discharge Manifold.
6. Install O-Ring, then Back-up-Ring on exposed Cylinder.
Back-up-Rings go to low pressure side of the
O-Rings. Lubricate O-Rings and Back-up-Rings on
exposed Cylinder. Exercise caution when slipping
Manifold over Cylinders to avoid damaging Cylinder
O-Rings. Completely press Manifold over Cylinders.
NOTE: On Model 390, Discharge Valve Adapter will
press into Cylinders when Manifold is reassembled
to crankcase.
7. Replace two (2), four (4) or eight (8) Hex Flange Nuts
and torque per chart.
NOTE: Replace all original Shims if used. When
new manifold is used reshim pump. When starting
the pump, check to see that there is no Cylinder
motion as this will cause premature failure of the
cylinder O-Rings. Center Cylinder motion indicates
improper shimming. Refer to Tech Bulletin 017 for
more information.
CAUTION: Before commencing with service, shut off drive (electric motor, gas or diesel engine) and turn off water supply to
pump. Relieve all discharge line pressure by triggering gun or opening valve in discharge line.
After servicing is completed, turn on water supply to pump, start drive, reset pressure regulating device and secondary valve, read
system pressure on the gauge at the pump head. Check for any leaks, vibration or pressure fluctuations and resume operation.