If you work with hydraulic systems—whether you’re a heavy equipment operator, a maintenance manager, or a small business owner who relies on industrial machinery—you already know how critical a hydraulic pump is. It’s the heart of the whole setup: it converts mechanical energy into fluid flow that powers cylinders, motors, and every other moving part. But here’s the thing: even the best hydraulic pumps aren’t invincible. After 10+ years as a hydraulic pump supplier, I’ve seen every issue you can think of, and most of them boil down to avoidable mistakes, wear and tear, or just plain bad luck. In this post, I’m breaking down the most common hydraulic pump problems, why they happen, and what you can do to spot (and fix) them before they bring your operations to a halt. Hydraulic Pump
First, let’s get one thing straight: most hydraulic pump issues don’t pop out of nowhere. They’re usually the result of small, unaddressed issues that snowball. Take contamination, for example. That’s the #1 problem we see day in and day out. Contamination in hydraulic fluid isn’t just a “dirty fluid” issue—it’s tiny particles: metal shavings from worn parts, dust, water, even seal flakes that get into the reservoir. When those particles end up in the pump, they act like sandpaper. Over time, they scratch the interior components (like the pistons, gears, or vanes inside the pump), create gaps where fluid leaks out, and cause excessive friction. We’ve had customers come to us with a pump that’s only 2 years old, and we tear it down to find the vanes completely worn down because they skipped monthly fluid filter changes. Even a tiny amount of water in the fluid is bad—It causes rust, corrodes internal parts, and breaks down the fluid’s lubricating properties. We always tell our clients: if you’re not checking your fluid’s cleanliness regularly, you’re setting yourself up for a pump failure.
Next up: cavitation. This is one that even seasoned operators mix up sometimes. Cavitation happens when the pump doesn’t get enough fluid to operate properly. Think of it like trying to suck a drink through a straw with a kink in it—you pull hard, the fluid pressure drops so low that it forms tiny vapor bubbles, and when those bubbles get to higher pressure areas inside the pump, they implode. Those tiny explosions are loud (you’ll hear a high-pitched whining or rattling) and they eat away at the pump’s interior over time. What causes cavitation? A clogged inlet filter or line, a leak in the suction line that lets air get in, or even a fluid that’s too cold and thick to flow properly. I once had a construction company client who was running their machine in freezing weather and didn’t warm up the fluid first—their axial piston pump had a huge pitted surface from cavitation after only 3 months. Cavitation doesn’t just damage the pump; it also reduces efficiency, so your machine uses more fuel or power to do the same work. That’s a double hit for your budget.
Then there’s the whole “no flow or low flow” issue. This is the most obvious one because if your hydraulic pump isn’t moving fluid, your loader isn’t lifting, your press isn’t operating, whatever it is, it’s dead. What causes low flow? Sometimes it’s a worn pump—like the gears in a gear pump are ground down, so they can’t move enough fluid. Or it could be a misadjusted pressure relief valve that’s set too low, so all the fluid is leaking back to the reservoir instead of going to the system. We also see this when the pump is installed wrong: if the inlet line is too small, it can’t supply enough fluid, or if the pump is rotating in the wrong direction (yes, that’s a thing—reverse rotation kills flow instantly). A lot of people don’t check rotation when they install a new pump, especially if they’re replacing an old one. We always tell our technicians to mark the rotation direction on the old pump before removing it, so they don’t make that mistake.
Another common headache: leaks. Hydraulic leaks are annoying, messy, and dangerous (that fluid is hot and slippery, not to mention bad for the environment). Where do leaks come from? Usually worn seals or gaskets. Over time, rubber seals dry out, crack, or get damaged by contamination, so fluid seeps out. Or loose fittings—vibration from the machine can loosen hose connections over time. Wait, but sometimes leaks aren’t just external. Internal leaks are even worse because you can’t see them. That’s when fluid is leaking past internal components (like between the piston and cylinder wall) instead of going out to the system. Internal leaks make the pump inefficient, so you use more power, and eventually, the pump can’t build pressure at all. We’ve had customers ignore small external leaks for months, and end up with internal leaks that meant a full pump replacement instead of just a $50 seal kit. Don’t skip those small leaks—they’re warning signs.
Pressure issues are another big one. Either the pressure is too high or too low, both of which are problems. Too low, and your machine doesn’t have enough power to do the job. Too high, and you risk bursting hoses, damaging cylinders, or even blowing the pump apart. Pressure issues are often tied to the pressure relief valve, which is supposed to regulate pressure. If the valve is stuck open, pressure drops; if it’s stuck closed, pressure spikes. But it can also be the pump itself—if the pump’s internal clearances are too big from wear, it can’t build the required pressure. We once had a woodworking shop that kept blowing their hydraulic hoses every other week—turns out their pressure relief valve was rusted shut, so the pump was pushing way over the recommended pressure. It’s a simple check, but a lot of people don’t do routine pressure tests.
Now, let’s talk about human error, which is a huge one that many people overlook. I know, I know—you’re busy, you’ve got a thousand things on your plate. But cutting corners on installation, maintenance, or operation is where most pump problems start. For example: installing a pump without properly priming it. Priming is when you fill the pump with fluid before turning it on, so you don’t get air bubbles. Skip that step, and cavitation happens instantly. Or using the wrong fluid. Every hydraulic pump is designed for a specific type of fluid—using a fluid that’s too thin or too thick can cause all kinds of issues, from increased wear to overheating. We’ve even had a customer use motor oil instead of hydraulic fluid because it was “cheaper,” and their pump seized up within a week. That’s not a failure of the pump—that’s a failure to follow basic guidelines. Also, overloading the system. Pumps have a maximum capacity, and if you’re running your machine 24/7 beyond that, the pump wears out way faster than it should. We recommend keeping your pump’s load at 80% or less to extend its lifespan—simple, but effective.
Wait, let’s not forget overheating. Hydraulic systems run hot sometimes, but if the fluid is consistently over 180°F, that’s a problem. Hot fluid breaks down faster, loses its lubricating properties, and causes the pump’s internal parts to expand, leading to more wear. What causes overheating? A clogged cooling system, too much internal leakage, or using fluid with the wrong viscosity. I once saw a mining company’s pump run at 200°F because their cooler was covered in dust—after cleaning the cooler, the temperature dropped 30 degrees, and the pump ran like new for another 5 years. Overheating is easy to miss because you don’t always monitor fluid temperature, but it’s a silent killer of hydraulic pumps.
Now, the good news: most of these problems are preventable, or at least catchable early. But if you’re already dealing with a failing pump, don’t wait until it’s too late. As a hydraulic pump supplier, we’ve helped hundreds of customers replace faulty pumps, fix underlying issues, and get their operations back up and running fast. Whether you need a replacement pump, a repair kit, or just advice on maintaining your current setup, we’re here to help. Don’t let a small hydraulic pump problem turn into a major breakdown that costs you time and money. Reach out to us to discuss your needs, and we’ll help you find the right solution for your equipment.
Before I wrap up, let’s go back to what I said earlier: hydraulic pumps are tough, but they’re not indestructible. The key is routine maintenance: check your fluid cleanliness monthly, change filters regularly, test pressure and temperature, fix small leaks right away, and make sure you’re using the right fluid and installing everything correctly. Skip those steps, and you’ll end up with the issues I listed—and a big repair bill. If you’re not sure where to start, or you’ve noticed your pump acting up (weird noises, low flow, leaks), don’t hesitate to get in touch to talk through the problem. We’re here to support you every step of the way.
Main Control Valve References
Hydraulic Institute. (2020). Hydraulic Pump Maintenance Best Practices. Hydraulic Machinery Association.
ISO 4406:2017. (2017). Hydraulic fluid power—Fluids—Method for coding the level of contamination by solid particles. International Organization for Standardization.
US Department of Energy. (2019). Reducing Hydraulic System Downtime: Common Failure Causes and Mitigation Strategies. Industrial Technologies Program.
Yantai Dayun Machinery Parts Co., Ltd.
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