10 Warning Signs Your Hydraulic Pump is Failing (And What to Do Next)
Is your equipment acting up? Don't ignore these 10 critical symptoms of hydraulic pump failure. Learn how to diagnose the problem and the steps to take for a reliable fix.
The hydraulic pump is the heart of your machinery. Whether it's a tractor, excavator, or press brake, a healthy pump is what generates the flow and pressure needed to perform work. When it starts to fail, the entire system suffers.
Ignoring the early warning signs can lead to catastrophic failure, costly downtime, and even damage to other expensive components like valves and cylinders. This guide will walk you through the 10 most common symptoms of a failing pump, how to confirm your suspicions, and the critical next steps to take. [Tracsol Automotive]
Understanding the Pump's Role
First, a quick primer. The hydraulic pump's job is simple but critical: it converts mechanical energy from the engine into hydraulic energy by creating flow. It does not create pressure directly; pressure is created by resistance to that flow. A failing pump cannot generate sufficient flow, resulting in a loss of power and performance. [Tracsol Automotive]
The 10 Key Symptoms of a Failing Hydraulic Pump
If you notice any of these signs, it's time to investigate.
1. Slow Operation
Symptom: The most common early sign. Cylinders extend and retract slowly, attachments cycle sluggishly, and the machine feels weak and unresponsive, even at full engine RPM.
What it means: The pump can no longer generate the required flow volume to move the system's actuators at normal speed.
2. Loss of Power or Weak Performance
Symptom: The loader won't lift a full bucket, the log splitter stalls under pressure, or the press can't generate enough force.
What it means: The pump is failing to generate the flow needed to achieve the system's pressure rating, resulting in a loss of force.
3. High Operating Temperature
Symptom: The hydraulic fluid is overheating (significantly hotter than the engine coolant temperature). You might see warning lights or even smell hot oil.
What it means: Internal leakage within the pump (bypassing high-pressure fluid back to the low-pressure side) creates friction and heat, cooking your fluid and damaging other components.
4. Unusual Noises: Cavitation and Aeration
Symptom: 1. Cavitation: A high-pitched whine or scream, often like marbles are circulating. This is a severe symptom. 2. Aeration: A loud knocking or banging sound, similar to a diesel engine knock.
What it means: Cavitation means the pump is starved for oil (inlet restriction). Aeration means air is being sucked into the inlet side through loose fittings or a damaged shaft seal. Both destroy pumps quickly.
5. Increased Noise Under Load
Symptom: The pump noise noticeably changes (gets louder, higher-pitched, or begins to groan) when a function is activated.
What it means: Internal components like vanes, pistons, or gears are worn and are struggling to maintain pressure, causing vibration and noise.
6. Hydraulic Fluid Contamination
Symptom: You find metallic particles (silvery sparkles) or bronze/copper flakes in the hydraulic fluid or on the suction strainer.
What it means: This is the smoking gun. The pump is physically grinding itself apart from the inside due to wear or loss of lubrication.
7. Jerky or Erratic Movement
Symptom: Cylinders chatter, jerk, or stutter instead of moving smoothly.
What it means: The pump's flow is not consistent. This can be caused by severe internal wear, damaged bearings, or a damaged drive coupling.
8. Pump Shaft Seal Leak
Symptom: A visible, persistent leak at the pump's input shaft, where it connects to the engine or transmission.
What it means: The shaft seal has failed. This is often caused by worn shaft bearings, which create play and destroy the seal. It’s a primary cause of aeration (see #4).
9. High Current Draw (Electric Pumps)
Symptom: An electric motor-driven pump trips breakers, blows fuses, or the motor gets excessively hot.
What it means: The pump is mechanically binding or under extreme load, forcing the electric motor to work harder and draw more amperage.
10. Failed Pressure Test
Symptom: This is the definitive diagnostic test. A pressure gauge reading confirms the pump cannot achieve the system's specified pressure.
What it means: Internal leakage is so severe that flow is bypassing within the pump before it can build pressure.
How to Test and Confirm a Failing Pump
⚠️ Safety Warning: Hydraulic testing can be dangerous. Fluid under high pressure can penetrate the skin and cause serious injury. Wear safety glasses and gloves.
Visual Inspection: Check for obvious leaks, especially at the shaft seal. Look for damaged lines, a collapsed suction hose, or a clogged reservoir breather cap.
Fluid Check: Check the fluid level and condition. Smell it (burnt odor is bad), and look for metallic glitter or cloudiness (a sign of aeration).
Inlet Restriction Check: Use a vacuum gauge on the pump's inlet port. Excessive vacuum (over 5 inHg) indicates a clogged filter, stuck strainer, or too-viscous oil.
Flow Meter Test: The most accurate test. A hydraulic technician connects a flow meter to the system to measure the pump's output (GPM) under load. A pump that outputs significantly less than its rated flow needs replacement.
Pressure Test: Using a pressure gauge, deadhead the pump (lock the flow) and see if it can achieve the system's relief valve setting. If it can't reach pressure, the pump is weak.
Next Steps: Repair or Replace?
If your testing confirms pump failure, you have two options:
Replace with a New or Remanufactured Pump: This is often the best choice for reliability and warranty. It provides a known-good starting point.
Pump Repair Kit: For certain pumps, rebuild kits (with seals, gaskets, vanes, etc.) are available. This is a job for a skilled technician with a clean workshop, as internal tolerances are extremely tight.
Crucial Step: FLUSH THE SYSTEM!
A failing pump contaminates the entire system. Installing a new pump into a dirty system will cause it to fail immediately. You must:
Drain all old fluid.
Replace all filters and strainers.
Clean the reservoir thoroughly.
Flush the system with a cleaning fluid or cheap hydraulic oil to remove all metallic debris before adding the final, high-quality fluid.
Conclusion: Don't Ignore the Heart of Your Machine
Your hydraulic pump is too critical to ignore. Paying attention to these ten symptoms—especially slow operation, unusual noises, and fluid contamination—can help you catch a problem early. Proper diagnosis and, most importantly, a thorough system flush upon replacement will ensure your equipment returns to reliable, powerful operation for years to come.
Need help diagnosing your hydraulic issues? Our certified technicians are ready to help. Schedule a hydraulic diagnostic service with us today https://www.tracsolautomotive.com/