Pump Maintenance: Flushing the Hydraulic System

by The PIERCE Team on 5/25/16 9:26 PM

Do you have water in your hydraulic pump fluid? Water in your hydraulic system can lead to clogged valves and filters. Water in your pump can rust components. Rust in your pump and in the cylinders leads to mechanical failure. Read on for instructions on how to know and when to flush your system.

How to determine if you have water in the hydraulic fluid:

  • The pump does not build up pressure.
  • The hydraulic fluid starts looking milky or cloudy.
  • Water will freeze, impeding flow in colder climates.


Flushing your pump:

  1. Step 1 – Disconnect the hoses. Place the disconnected hoses into a bucket or drain pan to collect the hydraulic fluid from the cylinder.
  2. Step 2 – Drain the cylinder. In order to drain the cylinder retract and extend the cylinder until all the fluid is removed. The fluid will exit the hoses removed in step 1.
  3. Step 3 – Remove the reservoir and empty the fluid. The reservoir is usually located on the pump.
  4. Step 4 – While you have the reservoir off, use a mild parts cleaner to clean the filters and the inside of the reservoir. Mild parts cleaner can be purchased at your local auto parts store.
  5. Step 5 – Pull the valve out of the pump and clean with parts cleaner as well, flushing the block. The cleaner will flow out of the tubes into your collection bucket.
  6. Step 6 - Allow the parts cleaner to evaporate from the disassembled pump. This process takes about ten minutes.
  7. Step 7 – Reassemble pump, reconnect hoses, and fill the reservoir with AW46 (hydraulic fluid) or Dexron III (automatic transmission fluid) and purge the system until it’s full. Be sure NOT to mix the two fluids. Only use one type.

Your hydraulic system is flushed and ready to operate. Hydraulic pump maintenance keeps your Pierce equipment in working order and adds to the life of the product. Thank you for choosing Pierce.


PIERCE dealer


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This post was written by The PIERCE Team

At PIERCE we work as a team, a family. When you have a problem we combine our expertise and knowledge to find you an answer.

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