
Form No. 102977
Rev. 2 Jun. 02, 2022
10© SPX FLOW, Inc.
PROBLEM CAUSE SOLUTION
Pump is not delivering oil or
delivers only enough oil to
advance cylinder(s) partially
or erratically (continued).
11� Sheared drive shaft key(s) 11� Replace�
12� Motor rotating in working
direction�
12. Air motor: Air line connected into wrong
port�
13� Vacuum in reservoir� 13. Check for plugged vent in ller plug.
14� Low pressure pump worn� 14� Remove end cap from low pressure
gear pump� Clean pump, and replace
worn gears, shifting spool, body or end
cap�
Pump builds pressure but
cannot maintain pressure.
1� Check to see if there are
any external leaks� If no
oil leakage is visible, the
problem is internal� If using
a double acting cylinder,
remove it from the system
to ensure that the leak is not
in the cylinder�
1. Seal leaking pipe ttings with pipe
sealant�
2� To test for a leaking control
valve, lift the pump from
the reservoir but keep the
lter in the oil. Remove the
drain line to see if the oil is
leaking from the valve� If
the valve is not leaking, the
internal check valve could
be leaking� Refer to the note
concerning checking for oil
leaks at the beginning of
this troubleshooting Guide�
2. Clean, reseat or replace ow control
valve parts� If the internal check
valve(s) are leaking, the pump must be
dismantled and the seat areas repaired,
poppets replaced, etc�
3� Leaking pressure switch
seal�
3� Repair or replace seal�
Pump will not build full
pressure.
1� Faulty pressure gauge� 1� Calibrate gauge�
2� Check for external leakage� 2. Seal faulty pipe tting with pipe sealant.
3� Check the external pressure
regulator� Check the relief
valve setting�
3� Lift the pump from the reservoir, but
keep the lter immersed in oil. Note the
pressure reading when the relief valve
begins to open� If functioning normally,
it should start to leak o at relief valve
pressure�
4� Look for internal leakage in
double-acting cylinders�
4� Remove the cylinder from the pump�
If the pump builds full pressure, the
cylinder is defective�
5. Check for leaks in the ow
control valve�
5� Clean and reseat or replace parts�
Troubleshooting Guide Continued