Section 8
High Pressure Water System
20425618
5-2005/Rev 0
8-30
Plunger Button Sockets, Seals and Retainer Pins
1. Remove the flat snap rings and plunger retainer pins on both ends of the piston.
2. Inspect the snap rings and the pins for unusual wear or deformation. Clean and inspect the
pin holes for unusual wear, deformation or hole enlargement.
3. Remove the plunger button o-ring and backup ring from each plunger socket. Take care
not to scratch or damage the seal groove surfaces.
4. Clean and inspect the seal grooves for residue buildup or surface marks that could cause
seal leaks.
5. Inspect the plunger button sockets for unusual wear.
NOTE
Due to the high contact force between the piston and the plunger, the plunger may
make an impression in the bottom of the socket. This compression mark or
indentation is normal.
6. Apply FML-2 grease to new plunger button backup rings and o-rings. Install the rings in
the internal groove in the plunger socket. If the backup ring is not installed the plunger
can be forced out of the plunger socket.
7. Install the retainer pins, verifying that each pin moves freely without excess side play in
the pin holes.
8. Install the flat snap rings over the pins.
9. Install the plungers and check the snap-in feature of the plunger attachment. Use the
plunger removal tool to ensure the pins retract to release the plunger, and close to retain
the plunger in a uniform manner.
Internal Check Valves
It is not necessary to service the internal check valves unless a problem is suspected. If the check
valves or the internal passages in the piston require service, plunger button, seal and pin servicing
is also recommended. See Figure 8-20, Hydraulic Piston.
1. Loosen the set screw and remove the check valves and o-rings. Clean the internal
passages.
2. Apply FML-2 grease to a new o-ring and install the new o-ring in the check valve
passage. Use a blunt, pencil-like instrument to position it in the bottom of the passage.
3. Clean and install a new check valve with the chamfered end toward the o-ring.
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