Plunger Pump Maintenance

How to spot a pump part that needs to be replaced

Things to look for when trying to identify a worn pump part.

Connecting Rods

The proper clearance between the bronze insert and the eccentric should be 0.004 to 0.005.  If clearance is greater, brass shims located between the halves of the connecting rod may be removed to take up wear in the bronze insert bearing.  Shims should be removed evenly from each side of the connecting rod halves.>

Packing Gland

The packing gland should be adjusted to allow for a slight amount of seepage through the stuffing box.  Care must be taken to tighten all gland bolts evenly.  When there is no further take-up the packing should be replaced.>


Eventually the plunger may become worn to an “ hourglass” shaft.  If wear on the plunger is 3/32” or less on the diameter, the plunger can be remachined.  If wear is greater than this a new plunger should be installed.

Ball Valve & Valve Seats

The standard diameter of the ball valve is 5-1/8”.  If it should become worn to 4 ½” it should be replaced.   The valve seat facing should be checked for wear.>

The interval in which the periodic checks are made would depend on the pump usage, operating pressures and abrasive nature of the sludge.

This is an important part of the Owner’s & Operator’s Manual, which is a vital link to long lasting trouble-free pump operations.  What follows are some key procedures that will make your operating hours and days pleasant.

Things Required to Perform Maintenance Program:

- Wear chemical safety goggles when making gland adjustments.

- Make certain the drive motor is locked out before operating.


Tools Required for pump maintenance:

Certified torque wrench>

Socket heads required: 7/8, 15/16, 9 /16, ½, ¾ and 1-1/8

2 – engineer wrenches (size: 3/4)

1 – large flat head screwdriver

1 – Gallon of 90 Gear Oil or equivalent

1 – Feeler gauge