Why Your Hydraulic Cylinder Isn’t Holding Pressure—Top Reasons & Fixes

A hydraulic cylinder that isn't holding pressure can bring operations to a grinding halt. Whether it's in construction equipment, manufacturing machinery, or other industrial applications, this issue needs immediate attention to avoid costly downtime and repairs. Understanding why your hydraulic cylinder isn’t holding pressure—and knowing how to fix it—can save both time and money.

Let’s explore the top reasons for pressure loss in hydraulic cylinders and how you can resolve these issues effectively.

Common Reasons Your Hydraulic Cylinder Isn't Holding Pressure

1. Leaking Seals

One of the most common reasons for pressure loss is leaking seals. Seals are crucial for maintaining pressure within the hydraulic system, and over time, they can wear out or become damaged due to:

• Aging and wear

• Excessive heat or pressure

• Contamination in the fluid

If the seals around the piston or gland are damaged, they’ll allow fluid to escape, causing a drop in pressure.

Fix: Inspect the seals for visible wear, cracks, or tears. Replacing the seals is often the most straightforward fix. Always use high-quality replacement seals that match the specifications of your cylinder.

2. Damaged Cylinder Tube

The cylinder tube provides the surface for the piston to move back and forth. If the tube becomes scratched or damaged, it can cause internal fluid leaks, resulting in pressure loss. This issue is often caused by:

• Contamination in the hydraulic fluid

• Poor maintenance practices

• Excessive wear from high-pressure operations

Fix: Inspect the tube carefully for scratches, gouges, or corrosion. In severe cases, the tube may need to be replaced. Regular cleaning and filtration of hydraulic fluid can help prevent damage to the cylinder tube.

3. Internal Leaks in the Piston or Rod

If there’s an internal leak in the piston or rod area, fluid can escape from the cylinder, which causes pressure loss. This is commonly caused by:

• Worn or damaged piston rings

• Debris or contamination affecting the piston

• Improper assembly or installation

Fix: Check the piston and rod for signs of wear or damage. If necessary, replace the piston rings or components. Keeping hydraulic fluid clean and free of contaminants is key to preventing this problem.

4. Faulty Relief Valves

Relief valves are designed to protect the hydraulic system from excessive pressure. However, if these valves malfunction, they may open prematurely, releasing fluid and causing pressure loss.

Fix: Inspect the relief valve for wear or dirt buildup. Clean or replace the valve if needed. Ensuring that the system is regularly maintained will help keep the relief valve functioning correctly.

5. Clogged or Dirty Hydraulic Filters

Hydraulic filters are responsible for removing contaminants from the fluid. If the filter becomes clogged, the fluid can become contaminated, leading to pressure loss and damage to other components.

Fix: Regularly check and replace the hydraulic filter. Clean filters can help maintain fluid quality, which is vital for the proper functioning of the hydraulic cylinder.

6. Air in the Hydraulic Fluid

Air trapped in the hydraulic fluid can cause a loss of pressure and affect the overall performance of the cylinder. This can be due to:

• Improper bleeding of the system

• Leaks in the suction side of the pump

• Improperly filled fluid reservoirs

Fix: Bleed the air from the system properly, and ensure that the fluid is filled to the correct level. Check for any leaks in the suction lines that might be introducing air into the system.

How to Prevent Hydraulic Cylinder Pressure Loss

Preventing hydraulic cylinder pressure loss starts with proper maintenance and care. Here are a few tips to keep your hydraulic system in optimal condition:

• Regularly inspect seals, rods, and pistons to detect wear early.

• Use clean hydraulic fluid and ensure it’s filtered regularly.

• Maintain the correct pressure settings for your specific equipment.

• Clean your hydraulic filters to avoid blockages and contamination.

• Monitor for air in the system and bleed the lines as needed.

Conclusion

If your hydraulic cylinder isn’t holding pressure, it’s critical to act fast. By identifying and addressing the root cause—whether it's leaking seals, a damaged tube, or a faulty relief valve—you can restore the system’s performance and prevent further damage. Regular maintenance, thorough inspections, and using the right components will help extend the life of your hydraulic cylinders and ensure smooth, pressure-maintaining operation.