8 Sure Signs Your Hydraulic Cylinder Is Failing

The hydraulic cylinder is a core part of your semi-truck's hydraulic system. It converts fluid pressure into linear force, which allows you to operate attachments like dump beds.

Over time, your cylinder can wear down from constant use and exposure to debris. When this wear and tear reaches a critical point, it can prevent your system from working at full capacity, or at all. It's useful to know the sure signs your hydraulic cylinder is failing so you can catch any issues with this part early and fix them before a major breakdown occurs.

Strange Noises During Operation

Have you noticed any new sounds when you run your hydraulic system? Grinding, knocking, or squealing noises aren’t normal. These sounds often point to internal problems within the cylinder.

For instance, a grinding noise might suggest metal parts are scraping against each other due to a lack of lubrication or internal damage. A knocking sound could mean air is trapped in the hydraulic fluid, a condition called aeration. It could also point to a loose piston or worn-out seals. Squealing sounds are typically associated with high-pressure fluid leaks or components that aren't moving smoothly.

You shouldn't ignore these auditory clues; they’re direct warnings that something inside your hydraulic cylinder needs attention.

A Noticeable Drop in Performance

Your hydraulic system is designed for power and precision. A healthy cylinder provides consistent force and speed. If you notice a slowdown in your equipment's movements or a general lack of power, the cylinder might be the culprit. This loss of performance means the cylinder isn't converting hydraulic pressure into mechanical force as efficiently as it should.

This issue could stem from internal leaks, where hydraulic fluid bypasses the piston seal instead of pushing it. Worn seals or scoring on the cylinder bore can cause these leaks. A drop in performance slows down your work and puts extra strain on other parts of your hydraulic system, like the pump, as it works harder to compensate for the cylinder's inefficiency.

External Fluid Leaks

One of the most straightforward signs of a failing hydraulic cylinder is a visible fluid leak. Check around the cylinder rod, seals, and fittings for any hydraulic fluid. A leak around the rod seal is a common problem, as this seal is constantly in motion and exposed to the elements.

While a small amount of fluid might seem minor, it points to a compromised seal. Over time, that small leak will worsen, which leads to a loss of hydraulic fluid and pressure. Low fluid levels can cause the entire system to overheat and fail. You should address external leaks promptly to prevent more extensive damage.

The Cylinder Rod Shows Damage

The cylinder rod is the polished, chrome-plated component that extends and retracts. It needs a smooth, clean surface to maintain a proper seal. You should inspect the rod for any signs of physical damage, like scratches, dents, or corrosion.

Damage to the rod can tear the rod seal as it moves, which creates a path for fluid to leak out and for contaminants to get in. Scratches can occur when debris gets pulled into the cylinder. Corrosion, or rust, weakens the rod's surface and can also damage the seals. A damaged rod is a clear indicator of trouble.

The System Starts To Overheat

Hydraulic systems operate within a specific temperature range. If you notice your system is running hotter than usual, it's a sign that something is wrong. A variety of issues can cause overheating, but a failing cylinder is one potential source.

Internal leaks within the cylinder can cause the hydraulic fluid to flow at high pressure through small gaps, which generates a lot of heat. This process, known as fluid friction, raises the overall temperature of the system. Excessive heat degrades the hydraulic fluid, damages seals, and can cause metal components to expand, which leads to more friction and wear.

Jerky or Unpredictable Movements

Your hydraulic equipment should operate with smooth, controlled motions. If the movements become jerky, erratic, or unpredictable, you might have air in your hydraulic fluid or a problem with the cylinder's internal seals. Air contamination, also known as aeration, can make the fluid compressible, which results in jumpy movements.

Worn or damaged piston seals can also cause this problem. If the seal allows fluid to leak from one side of the piston to the other, the cylinder can't hold its position steady under a load. This can be dangerous, especially when you need precise control over your equipment. Jerky movements are a definite sign that your cylinder needs a thorough inspection.

Increased Power Consumption

Is your engine working harder than it used to when you operate the hydraulic system? An inefficient hydraulic cylinder forces the pump to work overtime to achieve the same amount of force. This extra work requires more power from the engine, which you might notice as increased fuel consumption.

This inefficiency is typically due to internal bypassing, where fluid leaks past the piston seal. The pump has to move more fluid to make up for the leakage, which consumes more energy. If you're filling up your tank more frequently without a change in your workload, you should check your hydraulic system for performance issues.

An Increase in System Pressure

It might seem counterintuitive, but a failing cylinder can sometimes cause an increase in system pressure. This can happen if there's a blockage or restriction within the cylinder itself. For example, a piece of a broken seal or another internal component could obstruct the flow of hydraulic fluid.

When the fluid can't flow freely, pressure builds up behind the obstruction. This can put a massive strain on the cylinder, hoses, and pump. High pressure can cause catastrophic failure, like a burst hose or a damaged cylinder barrel. You should monitor your system's pressure gauges; any unusual spikes are a serious red flag.

Your Next Steps

If your hydraulic cylinder is on the brink of failing, you'll likely notice at least one of these signs. When you recognize that these are indicators of a component that's about to go out, you can take action as soon as you notice them to preserve your equipment.

At Higgs Parts, we sell HYVA parts for anyone who needs to replace parts of their semi-truck's hydraulic system. Our high-quality, affordable cylinders, valves, and underbody kits let you easily swap out broken, failing parts to keep your truck running as it should.