No Controls After Fluid Change on Cat 236B Skid Steer

[MikePhua]

The Cat 236B skid steer is a reliable and versatile machine, widely used in construction, landscaping, and agricultural tasks. However, like any piece of heavy equipment, it can sometimes experience issues that can disrupt work and cause frustration. One common problem that operators encounter is a sudden loss of controls after changing the hydraulic fluid. This issue can be quite perplexing, as the system may seem to malfunction immediately after what should have been a routine maintenance task.
In this article, we will explore potential causes of this problem, break down how hydraulic systems work, and provide detailed troubleshooting steps to resolve the issue of losing controls after a hydraulic fluid change.
Understanding the Hydraulic System on the Cat 236B
Before delving into troubleshooting, it’s important to understand how the hydraulic system works on a skid steer like the Cat 236B. Skid steers use hydraulics for a variety of functions, including steering, lifting, and operating attachments like buckets, forks, or augers. The system relies on hydraulic fluid, which is pumped under high pressure to activate various components, such as hydraulic cylinders and motors.
The hydraulic system consists of several key components:

• Hydraulic Pump: The pump draws fluid from the reservoir and forces it under pressure to the actuators.
  
• Hydraulic Cylinders: These are responsible for linear motion, such as raising and lowering the loader arms or tilting the bucket.
  
• Hydraulic Motors: These convert hydraulic energy into rotational motion for turning the wheels or driving attachments.
  
• Hydraulic Reservoir: The fluid is stored here until needed.
  
• Hydraulic Valves: These regulate the flow of fluid to various parts of the system.
  

The fluid must be clean, at the correct level, and at the right viscosity for optimal system performance.
Common Causes for Loss of Controls After Fluid Change
If you’ve recently changed the hydraulic fluid on your Cat 236B and are now experiencing no controls, there are several possible causes:

1. Incorrect Fluid Level: One of the most common causes for control loss after a fluid change is an incorrect fluid level. If the hydraulic fluid is too low or too high, the system will not function properly. Low fluid levels can lead to cavitation (air entering the pump), which can damage components and result in loss of control.
   
2. Air in the Hydraulic System: During a fluid change, air can be introduced into the system, especially if the fluid is not replaced properly or the hydraulic lines are opened. Air in the hydraulic lines can cause erratic or loss of control since the system relies on fluid pressure to operate efficiently.
   
3. Contaminated Fluid: If the fluid is not properly filtered during the change or if the wrong type of fluid is used, contaminants such as dirt, metal shavings, or moisture can enter the system. Contaminated fluid can clog filters and valves, causing reduced system performance or failure to operate at all.
   
4. Failed Hydraulic Components: If components like the hydraulic pump, valves, or actuators are damaged during the fluid change, this can result in a complete failure of the system. A pump failure, for instance, would prevent hydraulic fluid from being circulated properly, rendering the skid steer inoperable.
   
5. Incorrect Fluid Type: Using the wrong type of hydraulic fluid for your Cat 236B can cause severe operational problems. The machine requires a specific viscosity and specification of fluid, which, if not followed, can lead to poor performance, overheating, and ultimately system failure.
   
6. Blocked or Clogged Filters: During a fluid change, debris can dislodge and clog the hydraulic filters. These filters are responsible for cleaning the fluid as it circulates through the system. A clogged filter can restrict the fluid flow, preventing the proper pressure from being generated, leading to loss of function.
   

Step-by-Step Troubleshooting Guide
If you are experiencing a loss of controls on your Cat 236B after a hydraulic fluid change, here are some troubleshooting steps to help you identify and fix the issue:

1. Check the Hydraulic Fluid Level:
   • First, ensure that the hydraulic fluid is filled to the correct level as per the manufacturer's specifications.
     
   • If the fluid level is too low, top it up with the correct hydraulic fluid. If it's too high, carefully drain some of the excess fluid to bring it to the proper level.
     
2. Bleed the Hydraulic System:
   • After changing the hydraulic fluid, air may be trapped in the system. To fix this, you need to bleed the system to remove any trapped air.
     
   • To do this, start the engine and operate the controls in a slow, deliberate manner. Move the joysticks or levers back and forth to circulate fluid through the system. This can help push air out of the lines.
     
   • In some cases, it may be necessary to leave the engine running for several minutes or operate the loader arm and bucket through their full range of motion to expel the air completely.
     
3. Inspect the Hydraulic Fluid for Contamination:
   • Look at the hydraulic fluid to see if there is any visible contamination, such as dirt, metal shavings, or moisture. If you see any contaminants, you will need to perform a fluid flush.
     
   • A fluid flush involves draining the fluid, replacing the filter, and refilling the system with clean, fresh fluid. If contamination persists, it could indicate a deeper problem within the hydraulic system.
     
4. Check for Leaks or Blockages:
   • Inspect all hydraulic lines for signs of leaks, cracks, or blockages. Leaks could indicate damaged seals or hoses that need to be replaced. Blockages could be due to debris clogging the hydraulic lines or filters.
     
   • If you notice a significant leak or obstruction, repair or replace the affected parts.
     
5. Verify the Correct Hydraulic Fluid:
   • Ensure that the correct type of hydraulic fluid has been used during the change. Refer to the Cat 236B user manual to confirm the fluid specifications. Using the wrong fluid can lead to poor system performance or even damage to the hydraulic pump and other components.
     
6. Test the Hydraulic Components:
   • If the fluid level is correct and the system is free of air and contamination, test the hydraulic components. Check the operation of the loader arms, bucket, and any attachments.
     
   • If there is still no response from the controls, the problem may lie within the hydraulic pump or valves. In this case, it may be necessary to consult a professional mechanic or technician.
     

Preventative Maintenance for the Cat 236B
To avoid similar issues in the future, follow these best practices for maintaining your Cat 236B hydraulic system:

• Regularly Check Fluid Levels: Ensure that the fluid level is maintained within the recommended range. Low fluid levels can lead to cavitation and system damage.
  
• Replace Filters on Schedule: Always replace the hydraulic filters as per the manufacturer’s recommended intervals. Clogged filters can cause poor system performance and damage components.
  
• Use the Correct Hydraulic Fluid: Always use the fluid recommended by Cat for your specific model. Using incorrect fluid can cause long-term damage.
  
• Inspect for Leaks and Damage: Regularly inspect hydraulic hoses, seals, and fittings for leaks or wear and tear. Catching issues early can prevent more significant problems down the line.
  
• Bleed the System After Fluid Changes: If you change the hydraulic fluid, always bleed the system to ensure air is removed from the lines. This will help maintain smooth operation.
  

Conclusion
Experiencing a loss of control after a hydraulic fluid change on a Cat 236B skid steer can be frustrating, but with a methodical approach to troubleshooting, you can resolve the issue. By checking fluid levels, bleeding the system, inspecting for contamination, and ensuring all components are functioning correctly, you can quickly identify and fix the problem. Regular maintenance, proper fluid handling, and timely inspections will help keep your Cat 236B running smoothly for years to come.