The hydraulic pump serves as a core component of the power system in heavy equipment. Nearly all critical functions, such as digging, lifting, rotating, and moving, rely on its operation. As a result, a failure of even a single pump can lead to significant delays in the project and financial losses. To assist you in finding hydraulic pump failures, knowing common causes, and getting maintenance tips, we gathered this basic guide to help you spot a bad hydraulic pump.
4 Signs of Hydraulic Pump Failure
Some of the most common signs of hydraulic pump failure include overheating, unusual noise, leakage, and slow or unreliable performance. Being aware of these signs of pump failure often allows you to detect the problem before it causes project downtime.
Slow Operations
Is your excavator’s arm moving more slowly than it used to? Are the cycle times on your dozer’s blade lift getting longer? A noticeable drop in operational speed is one of the most common signs of a problem. This slow move means the pump is no longer delivering the required fluid flow. This is often a symptom of internal wear or leaks, forcing the pump to work harder for the same result.
High Fluid Temperature
A hydraulic system will naturally get warm during operation, but excessive heat is a major red flag. If the system’s fluid temperature regularly climbs above 180°F (82°C), you have a problem. High temperatures degrade hydraulic fluid, reducing its ability to lubricate and causing it to thin out. This can quickly damage seals and accelerate wear on the pump’s internal components.
Unusual Noises
You know what your machine sounds like during a normal workday. When new, unfamiliar sounds appear, listen closely. For example, knocking sounds or high-pitched whirring sounds. The most common cause of unusual noises is the contamination of hydraulic oil due to aeration or cavitation.
Interior and Exterior Leaks
Leaks may be the most obvious sign of a problem. Exterior Leaks: These are easy to spot. You might see puddles of hydraulic fluid under the machine or a coating of oily grime on hoses and fittings. This indicates a failed seal, a loose connection, or a damaged hose. Interior Leaks: These are much harder to detect. An internal leak happens when fluid bypasses a seal inside the pump, moving from a high-pressure area to a low-pressure one. You won’t see any fluid on the ground, but you will feel slow performance, loss of power, and overheating.
Since hydraulic pump installation and calibration require extremely high precision, once you confirm a replacement is needed, be sure to either have the new pump properly installed and calibrated or consult a professional technician. Following the correct procedure is fundamental to ensuring the new pump’s performance and long-term reliability.
8 Common Causes of Failing Hydraulic Pumps
Understanding why a pump fails is crucial for prevention. For off-road machinery operating in harsh environments, these causes are often interconnected. A small issue in one area can quickly cascade into a complete system failure.
Fluid Contamination
This is, without a doubt, the number one enemy of any hydraulic system. The internal components of a hydraulic pump have incredibly tight tolerances, and even microscopic particles can act like liquid sandpaper, causing abrasive wear. Sources of Contamination Include:
- External Debris: Dirt, dust, and moisture from the job site can enter through worn cylinder rod seals, breather caps, or during fluid top-offs.
- Internal Particles: Tiny metal shavings from the normal wear of gears, bearings, and other components can circulate through the system.
- Chemical Breakdown: Overheated or old fluid can break down, creating sludge and varnish that clog small passages.
Contamination doesn’t just cause wear; it reduces the fluid’s ability to lubricate and transfer heat, leading directly to other causes of failure on this list.
Cavitation
As mentioned, cavitation is the rapid formation and collapse of vapor bubbles in the hydraulic fluid. This happens when the pump’s suction side can’t get enough fluid, causing the local pressure to drop below the fluid’s vapor pressure. When these bubbles travel to the high-pressure side of the pump, they implode with tremendous force. This process physically chips away at metal surfaces, causing severe pitting and erosion on gears, vanes, and housings. Common causes of heavy equipment include a clogged suction strainer, a blocked or kinked suction hose, or using a fluid with a viscosity that is too high for the operating temperature.
Excessive Temperature
While overheating is a symptom, it is also a direct cause of failure. When hydraulic fluid gets too hot, its viscosity drops. This thin, watery fluid fails to provide an adequate lubricating film between moving parts, leading to metal-on-metal contact and rapid wear. High heat also cooks seals, making them hard and brittle until they crack and fail, causing both internal and external leaks.
Overpressure
Every hydraulic system is designed with a maximum operating pressure. Pushing your machine beyond its limits or a faulty pressure relief valve can subject the hydraulic pump to pressures it was not designed to handle. This immense strain puts a huge load on the pump’s internal bearings, shafts, and housing. Consistent overpressure will lead to fatigue, cracks, and eventually, a catastrophic mechanical failure.
Failing Seals
Seals are the unsung heroes of the hydraulic system. They contain high-pressure fluid and keep contaminants out. Over time, exposure to heat, pressure cycles, and contaminated fluid causes them to degrade. A failed shaft seal, for instance, can allow fluid to leak out and, just as importantly, allow air and dirt to be sucked in, triggering aeration and contamination.
Low Oil or Too Much Oil
Proper fluid management is fundamental. An overfilled reservoir can lead to foaming and heat buildup as the fluid has less space to dissipate heat. Operating a machine with too little fluid for even a brief period can cause the pump to overwork, leading to rapid increases in temperature and creating cavitation.
Wear and Tear
Critical parts like seals, pistons, gears, and vanes slowly degrade over thousands of hours of use. This gradual degradation leads to a loss of efficiency (often felt as slower operation or internal leakage) long before it results in a complete failure. Regular inspections and proactive replacement of worn parts as part of a maintenance schedule are a good way to keep the machine running smoothly.
Use of Low-Quality Fluid
The right type of fluid is critical for the health of your hydraulic pump. High-quality fluid is engineered with the correct viscosity, purity, and additive packages (like anti-wear and anti-foaming agents) to lubricate, cool, and efficiently transfer power. Low-quality or “bargain” fluids often fail at these core tasks. They can break down under heat, fail to provide an adequate lubricating film. Always use the fluid type and viscosity grade recommended by your machine’s manufacturer for the specific climate you are working in.
How do I Maintain My Hydraulic Pump?
Now that we know the problems, let’s focus on prevention. A proactive maintenance routine is the most effective way to avoid hydraulic pump failure and maximize the life of your equipment. These simple habits will save you thousands in repairs and downtime.
Stick to the Maintenance Schedule
Your equipment’s manufacturer provides a detailed maintenance schedule for a reason. Adhering to these service intervals for inspections and component replacements is the single best thing you can do. Don’t wait for a problem to appear; routine checks allow you to catch small issues before they become big ones.
Change the Hydraulic Fluid Often
Fluid is the lifeblood of your system. Follow the recommended change intervals based on operating hours. In particularly dusty or dirty environments, you may need to change it more frequently. Clean fluid lubricates better, cools more effectively, and extends the life of every component it touches.
Clean the Suction Strainer
The suction strainer is the pump’s first line of defense against large contaminants already in the tank. It is often overlooked during maintenance. A clogged strainer restricts flow to the pump, which is a primary cause of cavitation. Make sure it is inspected and cleaned with every fluid change.
Change Filters Often
Your hydraulic filters capture the fine particles that the strainer misses. A clogged filter will either starve the pump of oil or force fluid through a bypass valve, reintroducing contaminants back into the system. Pay attention to filter blockage indicators and replace hydraulic filters according to the schedule.
Check Pipes and Pipe Connections
Perform regular visual inspections of all hydraulic hoses, pipes, and fittings. Look for signs of abrasion, cracking, or bulging in hoses. Check fittings for any signs of weeping or leaks. A loose connection is easy to fix, but if left alone, it can lead to major fluid loss and system contamination.
Final Thoughts
Clearly, for a hydraulic pump to run healthily over the long term, daily maintenance is essential. As time passes, if you find yourself needing to replace it, whether you require a specific type of pump or need assistance in selecting the right one, the experts at FridayParts are always ready to help. With our wide hydraulic pump inventory, we’ll get your equipment back up and running quickly!
