Bulletins > How to Replace a Hydraulic Pump

How to Replace a Hydraulic Pump

This article describes the procedure for installing a replacement for a failed hydraulic pump. Following this procedure will ensure you get a satisfactory working life from the new pump. If you skimp on these steps the life of the replacement pump is likely to be shortened. A replacement pump will not run as well or last as long if the system is not cleaned out properly during the replacement and then properly maintained.

1. Determine the cause of the pumps’ failure.
2. Fix or eliminate the cause of the failed pump.
3. Retract all the cylinder rods.
4. Drain the tank.
5. Flush the tank through with diesel under pressure. Wipe dry with a clean cloth.
6. Replace the old filter elements with new ones of 10 microns or better. If the machine does not already have filtration, instead install a 10 micron filter on the return line, which must be able to filter at least 20% of the total pump flow. This can be installed on one return leg of a multiple pump circuit and will still work effectively.
7. Install the new pumps.
8. Fill the tank with new oil. Be sure to use the recommended grade of oil, and make sure you fill the whole system and not only the oil supply tank, which may only hold enough oil to handle changes in volume as the cylinder rods are extended. Pumps can fail due to lack of oil, so keep a close eye on the oil levels throughout the rest of the procedure.
9. Ensure that accumulators are bled and implements are securely blocked, then disconnect all lines to the motors and/or cylinders.
10. Move the control valve handles to open to activate each circuit to flush the lines and valves with new oil from the pump to all cylinders and motors.
    Check the oil level and add more oil if necessary.
11. Connect the lines to the blind end of the cylinders and all the fluid motors. Leave the rod end disconnected and activate the circuits slowly until the cylinder bottoms out with the engine at one-quarter throttle. This will flush old, dirty oil out of the rod end of the cylinder and draw new clean oil into the blind end. Repeat this for all the cylinders of the machine.
12. Re-connect the lines to the rod end of the cylinders.
13. Check the oil level and add more oil if necessary.
14. Operate all motors and cylinders at alternately for 30 minutes at full throttle.
15. Change the filter element.
16. Check the oil level and add more oil if necessary.