As you keep working, your skid steer may start lifting more slowly. The engine sounds normal, but the hydraulics just don’t have the power they had before. If your skid steer loses hydraulic power under load, the hydraulic pump may not be the problem. The oil may simply be getting hot and thinner, which can reduce hydraulic performance. Let’s go through a few checks to find the cause.
Is It a Pressure Problem or a Flow Problem?
First, let’s get a key concept straight. Your skid steer’s hydraulic system has two equally important functions:
- Pressure: This is the “muscle” of the system. Pressure, measured in PSI (pounds per square inch), determines how much force your machine can generate. Losing power under load is a pressure problem.
- Flow: This is the “speed” of the system. Flow, measured in GPM (gallons per minute), determines how fast your cylinders extend or your attachments run. A slow machine is a flow problem.
When your machine feels weak and can’t lift what it normally does, it’s failing to build or maintain adequate pressure. The root cause is almost always something allowing the pressurized oil to escape instead of doing useful work.
What Should I Check First When My Skid Steer Loses Hydraulic Power?
Always start with the basics. These five checks solve more than half of all hydraulic power loss issues and don’t cost you anything more than a few minutes of your time.
Check the Hydraulic Fluid
The fluid is the lifeblood of your system. Low or contaminated fluid is the main cause of hydraulic problems.
Level: Is the fluid at the correct level in the sight glass or on the dipstick? Check it according to the manual (some machines require checking with the arms up, some down).
Condition: What does it look like?
- Milky/Cloudy: You have water in your system. Water causes rust and doesn’t compress properly, leading to poor performance.
- Foamy/Bubbly: You have air in your system (aeration). Air is compressible, so your hydraulics will feel spongy and weak.
- Dark & Burnt Smelling: The oil has been severely overheated, breaking down its viscosity and ability to lubricate. This is a sign of a deeper problem, like a stuck relief valve.
Inspect the Hydraulic Filter
A clogged filter will starve your pump for oil. If the filter has a bypass valve, it will just let dirty oil circulate, causing wear. If it doesn’t, a clogged filter will choke the pump, causing cavitation and damage.
Field Tip: When you replace the hydraulic filter, cut the old one open with a filter cutter. Look at the paper element. A few tiny specks of metal are normal wear, but a filter full of shiny brass or silver “glitter” is a red flag that a pump or motor is failing internally.
Listen to the Pump
Your ears are a great diagnostic tool.
- Loud Whining: This usually indicates aeration—the pump is sucking in air from a loose fitting on the suction hose or a bad pump shaft seal.
- Loud Growling or Grinding: This is the sound of cavitation, which is far more destructive. It sounds like shaking a can of marbles and means the pump is being starved of oil from a clogged suction screen or collapsed inlet hose. If you hear this, shut the machine down immediately.
Check the Hydraulic Cooler
The cooler acts like the radiator for your hydraulic system. It’s usually located right next to the engine radiator. If its fins are packed with dirt, grass, or debris, it can’t dissipate heat. This causes the oil to overheat, thin out, and magnify any internal leaks you have.
Inspect the Quick Couplers
If you’re having trouble with an attachment, the problem might be as simple as a bad quick coupler. A worn or damaged coupler can restrict flow or fail to open properly, choking the attachment of power. Disconnect them, clean both ends, and inspect for damage.
Common Signs of a Hydraulic System
This is the most important question you can ask to narrow down the problem. With the machine warmed up and feeling weak, test every function.
| Symptom | What It Means | Likely Reasons |
|---|---|---|
| ALL functions are weak (lift, tilt, and drive). | The problem is “upstream” in a component shared by the entire system. | Main Hydraulic Pump, Main Relief Valve, Clogged Filter, Low/Bad Fluid. |
| ONLY ONE function is weak (e.g., lift is weak but tilt is fine). | The problem is “downstream” and isolated to that specific circuit. | Control Valve for that circuit, Seals in the lift cylinders, Hoses to that circuit. |
| ONLY the drive is weak (pulls to one side or won’t move). | The problem is likely in the hydrostatic drive system, which is often a separate closed-loop circuit. | Charge Pump, Drive Motor(s), Hydrostatic Pump. |
The Main Causes of Power Loss
If you’ve determined all functions are weak, you’re likely dealing with one of these three components.
1. The Main Hydraulic Pump
As a pump wears, the tight tolerances between its gears or pistons open up. When the oil is cold and thick, it can still build decent pressure. But when the oil gets hot and thin, it starts to “bypass” internally—slipping past the worn parts instead of being forced out to the system. This generates a lot of heat and results in a loss of pressure under load.
2. The Main Pressure Relief Valve
This valve is your system’s safety net. If pressure gets too high, it opens to protect components. But if it fails, it can cause major power loss.
- Weak Spring: The spring can weaken with age, causing the valve to open at a lower pressure than it should.
- Stuck Open: A tiny piece of debris can get lodged in the valve, holding it partially open. This creates a constant internal leak, bleeding off pressure and generating massive amounts of heat.
Mechanic’s Warning: Never adjust the relief valve to get “more power” without a pressure gauge. You are far more likely to cause a catastrophic failure than to fix your problem. The factory setting is there for a reason.
3. The Control Valve (Main Spool)
The main control valve directs oil to the function you command. Like the pump, the spools inside the valve body can wear over time, allowing oil to leak past them and return to the tank instead of going to your lift cylinders.
How Do I Test Hydraulic Pressure on a Skid Steer?
These steps will help narrow it down, but testing the pressure is the only sure way to know. Get a basic 0–5000 PSI hydraulic pressure gauge with the right fittings — it’s well worth buying for anyone who owns equipment.
Safety first: High-pressure hydraulic oil can shoot into your skin and cause serious harm. Always release pressure from the system before hooking up or removing the gauge. Wear safety glasses, and never use your hand to check for leaks.
Hook the gauge up to your auxiliary hydraulic port. Let the machine warm up first, then run the auxiliary circuit and block the flow. The gauge will read the max pressure your system can reach.
- Low pressure? The main relief valve is probably opening too early, or the pump is worn out and can’t build pressure.
- Pressure looks good at first but drops when you hold it steady? That means there’s a bad internal leak (worn pump or valve) that can’t keep pressure under load.
Conclusion
Losing hydraulic power under load is a clear sign there’s an issue in your system, so don’t ignore it. As we mentioned earlier, don’t automatically blame the hydraulic pump. Go through each diagnostic step to find the real problem. Once you know which part to replace, pick high-quality aftermarket parts from FridayParts. Our parts fit many machine models, come at fair prices, and ship fast. FridayParts, Fix it once, fix it right.
FAQs
Why are my auxiliary hydraulics weak, but lift and tilt work great?
It’s usually your quick couplers or the auxiliary control valve section. Since the main functions run strong, your pump and main relief valve are probably okay. The issue is only in the auxiliary circuit.
Can I use thicker hydraulic oil to fix lost power?
Don’t do that. It might seem to help for a short time by cutting internal leaks, but thick oil can starve the pump when it’s cold. That leads to cavitation and permanent damage. It’s just a quick fix that covers up the real issue and causes more trouble later.
My skid steer drifts to one side when I drive it. Is this a hydraulic issue?
Yep, this commonly points to trouble with the hydrostatic drive system. One drive motor is weaker than the other. The cause could be a worn motor, a faulty cross-port relief valve on that side, or a problem with the hydrostatic pump.
How much is it to swap out a skid steer hydraulic pump?
Prices change a lot depending on your machine model. A new pump can run anywhere from $800 up to $3,000 or higher. That’s why proper diagnosis matters so much. An hour checking things out can keep you from buying an expensive new pump you don’t actually need.
