Bobcat 743B Creeping Issue

[MikePhua]

The Bobcat 743B is a compact skid steer loader widely recognized for its reliability and versatility across many construction and landscaping applications. However, some owners of older 743B models have experienced a "creeping" issue, where the loader slowly moves forward or backward without operator input, especially when parked.
Common Causes of Creeping

• Hydraulic Control Valve Spring Weakness: Over time, the return springs within the hydraulic control valve can weaken, reducing their ability to center the valve spool and fully cut off hydraulic flow.
  
• Valve Spool Wear: Wear or corrosion on the valve spool and bore creates leakage paths, allowing fluid flow even in neutral positions.
  
• Hydraulic System Pressure: Some residual hydraulic pressure may remain in circuits due to faulty or worn components.
  
• Improper Hydraulic Pressure Settings: System relief valves or pressure regulators not correctly set can cause unintended circuit activation.
  

Temporary Solutions
A frequently mentioned field fix involves using zip ties or retaining bands on the valve spring to increase spring tension and improve spool centering. This can reduce creeping but is not a permanent solution and may not work on all units.
Recommended Repairs

• Valve Rebuild or Replacement: Overhauling the hydraulic control valve includes replacing worn spools, seals, and springs, restoring correct neutral positioning.
  
• Hydraulic System Inspection: Check and replace any worn hoses, fittings, and seals that contribute to unintended flow.
  
• Pressure Testing: Measure circuit pressures to ensure relief valves and regulators function within specification.
  
• Consult Service Manuals: Follow manufacturer guidelines for teardown, inspection, and assembly to ensure reliability.
  

Technical Terms

• Valve Spool: The sliding component inside the control valve that directs hydraulic fluid flow.
  
• Return Spring: A spring inside the valve that pushes the spool back to the neutral position.
  
• Neutral Position: The setting where all hydraulic flows should be blocked, resulting in no machine movement.
  
• Hydraulic Leakage: Unwanted flow of fluid through worn or damaged components causing creep or drift.
  

Anecdote from Operators
An owner of an early 1990s Bobcat 743B reported intermittent creeping that worsened over time. After experimenting with zip ties on the return springs—inspired by other user suggestions—the issue decreased but did not disappear. Eventually, the owner opted for a professional valve rebuild, which resolved the creeping issue completely, restoring precise hydraulic control and saving downtime.
Maintenance Tips

• Periodically inspect the hydraulic control valve for signs of wear or hardening of springs.
  
• Maintain hydraulic fluid cleanliness to prevent abrasive wear on valve components.
  
• Avoid leaving the machine engaged in high hydraulic load positions while idling.
  
• Schedule valve rebuilds during routine maintenance intervals to prevent creeping.
  

Summary
Creeping in older Bobcat 743B skid steers is typically caused by weakened hydraulic control valve springs, spool wear, or system pressure anomalies. Temporary fixes like zip tying springs can mitigate symptoms short-term but do not replace proper valve servicing. Rebuilding or replacing the hydraulic control valve restores precise operation and prevents creeping, prolonging machine life and improving safety and operator confidence.