A Guide to Repacking your Hydraulic Cylinder

Published: March 30, 2022 Last Updated: June 15, 2023 How To Series ,

hydraulic cylinder, gland, piston rod, o-ring, seal from hydraulic cylinders inc. Drift, fluid leaks, or changes in performance can all be signs that your hydraulic cylinder needs repacking. But don’t worry, the process is straightforward and takes less time than you might think. We take the mystery out of repacking a hydraulic cylinder by breaking down the process for you, step-by-step.

Prepare the Workspace

Your workspace should be clean to prevent contamination while disassembling and repacking the hydraulic cylinder. We also recommend waiting to open your hydraulic cylinder repacking kit until you are ready to install the new seals. Supplies you need handy for repacking your hydraulic cylinder include:

  • Hydraulic cylinder repacking kit (search by equipment model to find a kit compatible with your cylinder)
  • Clean replacement hydraulic oil
  • Wrench for removing the piston rod
  • Several clean, lint-free cloths to clean parts and wipe up spills
  • A large container for catching old hydraulic oil

STAY SAFE! If you plan to use equipment for raising and lowering heavy objects or weight-bearing purposes, brace the supported weight with jacks or blocks. This critical step helps prevent accidental injury to yourself and damage to expensive cylinder piston assemblies.

How to Repack a Hydraulic Cylinder

TIP: Pay attention to each component’s location during disassembly to ensure each part goes back where it belongs when reassembling the hydraulic cylinder. You should also use this time to check for fluid leaks and carefully inspect cylinder components and mounts for signs of corrosion, damage, or wear.

Take it slow and be careful, and you will have a new leak-free hydraulic cylinder in no time.

  1. Release all pressure from the cylinder.
  2. Loosen and remove the hydraulic lines from the cylinder.
    • Removing lines is important because it allows the last bit of pressure to escape the cylinder.
  3. Ensure the hydraulic cylinder is supported and won’t drop.
    • Once you stabilize everything, remove the pin from the rod end of the cylinder.
  4. Remove the gland from the cylinder.
    • This step is different for each cylinder manufacturer. Some glands are bolted, and others require a special tool you insert into small holes to turn the gland where the rod exits the cylinder. The gland may require a small tap or bump with a hammer to break it loose. Once loose, it should easily unscrew and pull away onto the piston rod.
  5. Remove the piston rod from the cylinder.
    • Prevent the piston rod from contacting other metal objects or falling onto the ground. Otherwise, you risk contaminating the piston rod or damaging its surface. You also want to ensure the fine threads inside the cylinder do not become damaged when removing the rod. Damage to these components could be costly.
  6. There are different ways to hold the rod to the piston.
    • A threaded rod can have the piston directly attached or have a nut or a nut and bolt holding the piston in place. When the rod is free from the cylinder housing, remove the piston from the rod. Keep all parts in the correct order and take a photo for reference if needed.
  7. Replace seals and O-rings on the piston and gland one at a time.
    • This will help to minimize confusion and correct placement. Be careful to identify and use the right seal. Some seals are very thin and can be easily damaged if not installed evenly. Ensure each groove is free of debris before replacing it with the new part.
  8. Reverse the process and reassemble the piston to the rod.
    • Always use a thread locking adhesive when replacing the piston rod bolt. Oil and clean all parts well before reassembly.
  9. Reinsert the gland into the cylinder.
    • Never use a thread locking substance on the gland threads.
  10. Replace all hydraulic lines and test for leaks around the new seals.

Including hydraulic cylinder repacking in your annual preventative maintenance routine helps you get more life out of your cylinders. While this repacking procedure should work for most welded rod cylinders, we recommend consulting a professional if you have specific questions about the process.

Hydraulic Cylinders, Inc. offers premium aftermarket seal kits for packing hydraulic cylinders. Our inventory also includes hydraulic cylinder pistons, heads, mounts, and other component parts for routine hydraulic cylinder servicing.

If you have questions about hydraulic cylinder packing, call 866-817-9044 to speak with our repair experts.

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