11.4
Replacing Power End Plunger, Seal Housing, and Seals
The power end plungers have a special surface treatment to reduce friction and wear; as a result they should not
need to be replaced on a regular basis. If the power end plunger seals are leaking they should be removed and
inspected. The power end plungers can be extracted from the pump without removing the fluid end. If the gear
reducer is in position 1, 2, or 16 it will need to be removed or indexed to another position. Otherwise, remove
the fluid end per instructions in
Section 9.6
and extract the power end plungers through the front of the power
frame.
1)
Using a 9/16” wrench loosen the two retaining screws on the plunger safety cover and slide it out of
the way.
2)
Remove the fluid end plungers per instructions in
Section 9.2
.
3)
Remove the power end plunger seal housing by removing the four hex head cap screws with a 9/16”
wrench. If necessary, rotate the pump to clear the housing of the power end plunger. Take
appropriate measures to prevent contaminants entering the power end.
4)
Remove the seal from the power end plunger seal housing. Clean the power end seal housing,
including the seal gland. Inspect the seal for signs of damage such as cracks or a dull wiping edge.
Replace seal as required.
5)
Before reinstalling the power end plunger seal housing the seal installation tool (PEC0232) will need
to be screwed onto the end of the power end plunger. This tool will help guide the seal onto the
plunger and prevent damage to the wiping edge. See drawing on following page.
6)
Gently guide the power end plunger seal housing over the installation tool until it is fully engaged
onto the plunger. Continue forward until the housing flange is in contact with the power end.
Reattach using the socket head cap screws.
NOTE: Power end leaks are typically a symptom of damaged power end plunger seals. It is not
necessary to continue with the following steps unless damage to the power end plunger or seal housing
is suspected.
7)
Remove the plunger lubrication relief system reservoir.
8)
Remove both side access panels from the pump using a 9/16" wrench.
9)
Rotate the pump until the outboard cylinder is at bottom dead center.
10)
Place a clean rag between the power end plunger and crosshead guide. While supporting the power
end plunger, remove the four screws using a 3/8" hex socket.
11)
Carefully remove the power end plunger through the side access window being careful not to
damage the outside sealing surface. Clean and inspect the power end plunger sealing surface.
Ensure it is not scored, scratched, or pitted. Replace the power end plunger if needed.
MSI Hybrid™ Well Service Pump Enhancement – The power end plunger is the key element of the
Hybrid pump design. It eliminates the shared sealing surface and positively prevents ingress of
pumpage to the power end.
Revision K 03/12/2019
MSI - A Division of Dixie Iron Works, Ltd. All rights reserved.
Page 69