Troubleshooting hydraulic issues with preparation and prework

Mar 25, 2015

Here are some basic steps when troubleshooting hydraulic problems:


  1. Obtain class room and hands-on training.
  2. Review the operating manuals.
  3. Review the schematics and bills of materials.
  4. Obtain and read the past field reports to learn and understand past repairs and maintenance that have been done on the system prior to problems.
  5. Look up the components on the internet to obtain specification sheets.


  1. Prepare to safely perform the work. Follow all mill procedures regarding working with hydraulic systems.
  2. Obtain and setup adequate lighting.
  3. Look over the hydraulic unit, mark up the direction of flow, if the valves are to be normally open or closed.
  4. Clean the hydraulic unit and surrounding area.
  5. Mark the various devices with "normal" operating parameters by tagging with the value or range, such as pressure, temperatures, flow rates, etc.


  1. Investigate the symptoms of the issues and what events occurred prior to failure.
  2. Investigate what the hydraulic unit is providing pressure for, such as a roll, hydraulic cylinder, or other component.  Has the component failed? If a new component, are there any possible issues such as hoses that have been connected incorrectly, an incorrect device installed, other faults?
  3. Use hydraulics system operations and troubleshooting knowledge to understand what might have happened.
  4. Proceed systematically, using Occam's Razor philosophy – the simpler answer is usually the correct one.
  5. Check:
    • operating parameters
    • pump direction
    • oil temperature
    • line temperatures
    • noise
    • filter condition
    • oil quality
    • air entrainment in the oil
    • air bleed vents
    • relief valves.

Finally, contact other resources for input/clarity on other questions you may have.

For more help with your hydraulic issues, contact your Valmet representative. The PM Maintenance School covers many topics.