Bobcat 751 Skid-Steer Loader Lift and Tilt Hydraulic Failure

[MikePhua]

The Bobcat 751, a compact skid-steer loader introduced in the mid-1990s, is renowned for its versatility and reliability in various construction and landscaping tasks. However, some operators have reported issues with the lift and tilt functions becoming unresponsive or intermittent. Understanding the potential causes and solutions for these hydraulic failures is crucial for maintaining optimal machine performance.
Common Causes of Lift and Tilt Hydraulic Failures

1. Hydraulic Fluid Contamination or Low Levels: Contaminants such as dirt or water in the hydraulic fluid can cause blockages or damage to components, leading to hydraulic failures. Additionally, low fluid levels can result in insufficient pressure to operate the lift and tilt functions effectively.
   
2. Faulty or Sticking Solenoid Valves: The solenoid valves control the flow of hydraulic fluid to the lift and tilt cylinders. If these valves become faulty or sticky, they may fail to open or close properly, disrupting the hydraulic flow and causing the lift and tilt functions to malfunction.
   
3. Worn or Damaged Hydraulic Seals: Over time, seals within the hydraulic system can wear out or become damaged, leading to leaks and loss of pressure. This can result in the lift and tilt functions becoming sluggish or unresponsive.
   
4. Electrical Issues: The Bobcat 751 utilizes a Bobcat Interlock Control System (BICS) that monitors various safety functions, including the operation of the lift and tilt controls. Electrical problems, such as faulty wiring or sensor issues, can cause the BICS to deactivate these functions as a safety precaution.
   

Diagnostic and Troubleshooting Steps

1. Check Hydraulic Fluid Levels and Quality: Ensure that the hydraulic fluid is at the recommended level and is free from contaminants. Replace the fluid if it appears dirty or has a burnt smell.
   
2. Inspect Solenoid Valves: Test the solenoid valves for proper operation. Listen for a clicking sound when the controls are activated, indicating that the valve is functioning. If no sound is heard, the solenoid may be faulty and require replacement.
   
3. Examine Hydraulic Seals: Inspect the seals on the lift and tilt cylinders for signs of wear or damage. Replace any compromised seals to restore proper hydraulic pressure.
   
4. Test Electrical Components: Use a multimeter to check for continuity in the wiring associated with the lift and tilt controls. Ensure that all connections are secure and free from corrosion.
   

Preventative Maintenance Tips

• Regularly Change Hydraulic Fluid and Filters: Adhere to the manufacturer's recommended maintenance schedule for fluid and filter changes to prevent contamination and ensure optimal performance.
  
• Inspect and Clean Solenoid Valves: Periodically check the solenoid valves for proper operation and clean them to prevent sticking or failure.
  
• Monitor Electrical Systems: Regularly inspect the electrical wiring and connectors for signs of wear or corrosion, and address any issues promptly to prevent system failures.
  

Conclusion
The lift and tilt functions of the Bobcat 751 are vital for its operation in various tasks. Understanding the common causes of hydraulic failures and implementing regular maintenance practices can help ensure the longevity and reliability of these functions. By staying proactive and addressing potential issues early, operators can minimize downtime and maintain the machine's performance on the job site.