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Spring Housing
Teflon Piston Wiper
Alignment Pins
Pump Head
Replacing the Ceramic Pistons
Figure 12 Wash Seal Assembly Replacement
Every six months, inspect the ceramic pistons. The complete spring
housing/pump head assembly (pump head and manifold) must be
removed from the pump when the ceramic pistons are being inspected
and/or replaced.
Remove the transfer tube that connects the pump head to the purge
valve body. Using the 9/64" Allen wrench, remove the pump head, piston
seal assemblies, manifold, and wash seal assemblies, if installed, as
described in the previous two sections. Using the same tool, remove the
four stainless steel Allen screws which attach the spring housing to the
frame drive casting (Figure 13).
The spring housing is spring loaded and these springs are compressed
when installed. It is necessary to back these four screws out slowly, first
loosening the two screws on one side about a turn, and then loosening
the two screws on the other side about the same amount, until the
assembly is free of the frame drive. Failure to follow this process may
cause damage to the screw threads in the frame drive casting. Pull the
spring housing free from the pump. The piston shafts are now visibly
protruding from the rear of the assembly.
The ceramic piston can fall out of the assembly at this point if the
assembly is not kept level. Gently remove the ceramic pistons from the
spring housing assembly. Clean the ceramic piston by sonicating in
soapy water and inspect the ceramic surface under magnification for
scratches. Any scratch or defect in the ceramic surface can contribute to
leaks.
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Wash Seal Assembly
Pump Head Manifold
Wash Seal Assembly
Piston Seal
Assembly
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