Hydraulic Cylinder Gland Leaks: Why They Happen and How to Fix Them

If you notice hydraulic fluid leaking around the cylinder rod, especially where it enters the head or gland, you’re looking at a common — but serious — issue. Gland leaks not only waste fluid, they also reduce system pressure and increase the risk of contamination and failure.

What Is the Gland on a Hydraulic Cylinder?

The gland (or head) is the front section of the cylinder that houses seals, wipers, and bushings. It’s where the rod enters and exits the cylinder. Its job is to contain pressure, prevent fluid escape, and keep contaminants out. When it leaks, one or more of these functions is compromised.

Main Causes of Gland Leaks

  • Worn rod seals: The most common failure point — seals degrade from heat, age, or pressure spikes.
  • Damaged rod: A scored, bent, or corroded rod tears through seals and causes leaks.
  • Incorrect seal installation: Twisted or pinched seals during assembly will leak immediately or soon after.
  • Contamination: Dirt or metal debris from the hydraulic system wears out seals prematurely.

Symptoms of a Leaking Gland

  • Visible fluid dripping or seeping from the rod area
  • Oil streaks along the cylinder body or machine frame
  • Rod covered in oil on every extension
  • Loss of system pressure or slow cylinder response

How to Fix a Gland Leak

  1. Remove the cylinder and disassemble it safely. Bleed off pressure first and cap lines.
  2. Inspect the rod: Check for scoring, rust, or bend — if damaged, replace or repair it before resealing.
  3. Replace all gland seals: Use an OEM or high-pressure seal kit rated for your cylinder’s specifications.
  4. Lubricate and properly install: Don’t force seals into position. Use seal installation tools and hydraulic oil for lubrication.
  5. Test after reinstallation: Run the cylinder under pressure and inspect for any signs of weeping or blowout.

Preventing Future Gland Leaks

  • Use rod wipers to keep out contaminants
  • Replace damaged rods before they destroy new seals
  • Flush your system and maintain clean fluid
  • Use correct installation methods to avoid twisting or damaging seals

Conclusion

Gland leaks in hydraulic cylinders are common, but they’re never minor. Every drop of oil escaping the rod seal is lost pressure and a sign of wear. With proper inspection, seal replacement, and rod condition monitoring, gland leaks can be stopped — and your hydraulic system stays strong and reliable.

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