9
© SPX FLOW, Inc.
Form No. 102371
Rev. 1 November 20, 2019
PROBLEM
CAUSE
SOLUTION
Pump is not delivering oil or
delivers only enough oil to
advance cylinder(s) partially or
erratically (cont’d)
4. Air leak in suction line
5. Dirt in pump, or filter plugged
6. Oil is bypassing through the
double-acting ram
7. Cold oil or oil is too heavy
(Hydraulic oil is of a higher
viscosity than necessary)
8. Relief valve or low pressure
unloading valve out of adjustment
9. Reservoir capacity is too small for
the size of the cylinder(s)
10. Defective directional valve
11. Sheared drive shaft key(s)
12. Motor rotating in wrong direction
4. Check and tighten the suction line
5. Pump filter should be cleaned
and if necessary, pump should be
dismantled and all parts inspected
and cleaned
6. By removing the ram and capping
the hoses, the pump and valve
can be checked to see if they hold
pressure
7. Change to lighter oil
8. Adjust as needed
9. Use smaller cylinder(s) or larger
reservoir
10. Inspect all parts carefully and
replace if necessary
11. Replace
12. Reverse rotation
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 ram,
remove it from the system to
insure that the leak is not in the
ram
2. To test for a leaking valve, lift the
pump from the reservoir keeping
filter in the oil. By removing the
drain line it is possible to see
the oil leaking from the valve. If
the valve is not leaking, one of
the internal check valves could
be leaking. Refer to the note
concerning checking for oil leaks
at the beginning of this trouble
shooting guide.
3. Check for sheared key
4. Leaking pressure switch seal
1. Seal leaking pipe fittings with pipe
sealant
2. Clean, reseat or replace valve
parts.
If the internal check valve(s)
are leaking, the pump must be
dismantled and the seat areas
repaired, balls replaced, etc.
3. Replace as needed
4. Replace as needed
