Troubleshooting the Auxiliary Pressure Relief Valve on the Case 85XT: A Guide for Operators

[MikePhua]

Introduction: The Case 85XT and Its Auxiliary Hydraulics
The Case 85XT is a versatile and powerful skid steer loader that has earned a reputation for reliability in a variety of applications. Like many modern skid steers, the 85XT comes equipped with auxiliary hydraulics, which allow it to power attachments such as augers, hydraulic breakers, and pallet forks. These attachments can greatly enhance the machine’s versatility, but they also bring with them the need for careful management of hydraulic pressure and flow.
One of the critical components in maintaining the functionality of auxiliary hydraulics is the auxiliary pressure relief valve. If this valve fails, it can result in issues ranging from decreased attachment performance to complete hydraulic failure. In this article, we’ll discuss common problems associated with the auxiliary pressure relief valve on the Case 85XT, along with potential solutions and best practices for troubleshooting and maintenance.
Understanding the Auxiliary Pressure Relief Valve
The auxiliary pressure relief valve is a crucial part of the hydraulic system on the Case 85XT. Its primary function is to protect the system from excessive pressure by diverting hydraulic fluid when pressure exceeds safe operating levels. Without a properly functioning pressure relief valve, hydraulic lines can burst, seals can fail, and components like pumps and motors can be damaged.
When the valve becomes clogged, worn, or otherwise malfunctioning, it can lead to several problems, ranging from low hydraulic pressure to inconsistent attachment performance.
Common Issues with the Auxiliary Pressure Relief Valve
While the Case 85XT is a well-built machine, there are several known issues that can arise with the auxiliary pressure relief valve. Understanding these issues can help operators recognize when the valve is the culprit behind hydraulic problems.

1. Low Auxiliary Hydraulics Pressure
   

One of the most common issues users experience is low auxiliary hydraulics pressure, which can severely reduce the efficiency of attachments. Attachments that rely on high pressure, such as hydraulic breakers or post drivers, may perform poorly or fail to operate entirely.
Possible Causes:

• Clogged relief valve: Over time, debris can build up in the relief valve, reducing its ability to regulate pressure effectively. If the valve cannot open at the correct pressure, it will restrict the flow of hydraulic fluid to the attachment, causing a noticeable drop in performance.
  
• Worn valve spring: The valve relies on a spring to open and close at the appropriate pressure level. If the spring is worn or damaged, the valve may not function correctly, leading to reduced hydraulic power.
  

Solution: Inspect and clean the relief valve regularly. If the valve is worn, replace the spring or the entire valve. It’s also a good idea to check the hydraulic fluid regularly to ensure it remains clean and free of contaminants that could clog the valve.

1. Intermittent or Erratic Pressure
   

In some cases, operators may experience erratic or intermittent auxiliary hydraulic pressure. This issue can cause attachments to work unpredictably, with the pressure fluctuating between too low and too high.
Possible Causes:

• Air in the hydraulic lines: Air bubbles trapped in the hydraulic lines can cause fluctuations in pressure, leading to inconsistent attachment performance.
  
• Relief valve sticking or failing: A relief valve that sticks or fails to open properly can result in spikes or drops in pressure. This can be particularly problematic when using high-demand attachments that require consistent pressure for optimal performance.
  

Solution: Bleed the hydraulic system to remove any air trapped in the lines. Inspect the relief valve for signs of wear or sticking. Cleaning or replacing the valve can often resolve this issue.

1. Complete Hydraulic Failure
   

In more extreme cases, the failure of the auxiliary pressure relief valve can lead to complete hydraulic system failure, rendering the machine inoperable.
Possible Causes:

• Severe internal damage to the relief valve: If the valve has suffered significant wear or damage, it may become completely inoperable, resulting in total loss of hydraulic pressure.
  
• Contaminated hydraulic fluid: Contaminants in the hydraulic fluid, such as dirt or debris, can cause blockages in the relief valve, leading to complete failure.
  

Solution: In the event of total hydraulic failure, inspect the entire hydraulic system for blockages and damage. Replace the relief valve and any other damaged components, and flush the hydraulic system to ensure clean fluid circulates through the system.
How to Diagnose and Fix Problems with the Auxiliary Pressure Relief Valve
Diagnosing issues with the auxiliary pressure relief valve can be challenging, but with the right steps, it’s possible to identify and fix the problem. Here’s a simple step-by-step guide:

1. Check for Hydraulic Fluid Leaks: Before diagnosing the relief valve, check the entire hydraulic system for any leaks. Leaks can cause pressure drops, and it’s essential to fix any leaks before proceeding.
   
2. Test Hydraulic Pressure: Using a pressure gauge, test the hydraulic pressure at the auxiliary output. Compare the reading to the specifications in the operator’s manual. If the pressure is low or inconsistent, the relief valve is likely the cause.
   
3. Inspect the Relief Valve: Locate the auxiliary pressure relief valve (typically near the hydraulic pump or control valve) and inspect it for any visible signs of wear or contamination. Remove the valve and clean it thoroughly. If the valve is worn or damaged, replace it with a new one.
   
4. Check Hydraulic Fluid Quality: Inspect the hydraulic fluid for cleanliness. If the fluid is contaminated, flush the system and replace the fluid.
   
5. Bleed the System: After replacing or cleaning the relief valve, bleed the hydraulic system to remove any trapped air.
   

Prevention and Maintenance Tips
Regular maintenance is key to preventing issues with the auxiliary pressure relief valve on the Case 85XT. Here are a few tips to ensure the valve continues to function properly:

• Change hydraulic fluid regularly: Dirty or contaminated fluid can damage components like the relief valve. Change the fluid according to the manufacturer's recommendations.
  
• Clean the relief valve during routine maintenance: During each service, inspect and clean the auxiliary pressure relief valve to prevent debris buildup.
  
• Use high-quality hydraulic fluid: Always use the recommended hydraulic fluid, as lower-quality fluids may not provide proper lubrication or pressure regulation.
  
• Avoid overloading attachments: Overloading attachments can put excessive strain on the hydraulic system and the relief valve. Always use attachments within the rated capacities.
  

Conclusion: Maintaining Peak Performance with the Case 85XT
The Case 85XT is a robust and reliable skid steer, and with proper maintenance, it can continue to perform at a high level for years. The auxiliary pressure relief valve plays a crucial role in ensuring that the hydraulic system operates efficiently, so it’s important for owners and operators to stay on top of any issues that arise.
By following regular maintenance procedures, diagnosing issues promptly, and using high-quality parts and fluids, you can avoid many common hydraulic problems and keep your Case 85XT in top condition for all your projects.