Bobcat 753 Drive Motor Failure and Hydraulic Troubleshooting

[MikePhua]

The 753 and Bobcat’s Skid Steer Legacy
Bobcat’s 753 skid steer loader was introduced in the mid-1990s as part of the company’s push toward compact, versatile machines for construction, landscaping, and agriculture. With an operating weight of around 5,400 pounds and a rated operating capacity of 1,300 pounds, the 753 was powered by a liquid-cooled Kubota diesel engine producing approximately 43 horsepower. Its hydrostatic drive system allowed for precise maneuvering, and its popularity led to thousands of units sold across North America and Europe.
The 753’s design emphasized simplicity and serviceability, but as machines age, drive motor issues—especially on one side—can emerge due to wear, contamination, or hydraulic imbalance.
Terminology Notes

• Hydrostatic Drive: A propulsion system using hydraulic fluid to power drive motors, allowing variable speed and torque without gears.
  
• Drive Motor: A hydraulic motor mounted to each side of the loader, directly powering the wheels or tracks.
  
• Case Drain Line: A low-pressure return line that carries leakage oil from the motor back to the reservoir, preventing pressure buildup.
  

Symptoms of Right-Side Drive Motor Failure
Operators may notice:

• Loader veers to one side during travel
  
• Right side lacks torque or fails to respond
  
• Jerky or delayed movement when turning
  
• Hydraulic whining or vibration from the affected side
  
• Increased heat or fluid consumption during operation
  

In one case, a contractor in Alberta reported that their 753 would pivot erratically and lose power on the right side. After inspection, they discovered the right drive motor had internal scoring and the case drain line was partially blocked.
Root Causes and Diagnostic Strategy
Drive motor failure typically results from:

• Contaminated Hydraulic Fluid
  • Metal particles or water in the fluid can damage motor internals
    
  • Dirty filters allow debris to circulate
    
• Case Drain Blockage
  • Restricted flow causes internal pressure buildup and seal failure
    
  • Can lead to motor overheating and cavitation
    
• Motor Wear or Seal Failure
  • Worn bearings or seals reduce efficiency and cause leakage
    
  • Shaft play can lead to uneven torque delivery
    
• Pump Imbalance or Valve Malfunction
  

• Uneven pressure from the hydrostatic pump affects motor performance
  
• Control valve wear can cause directional lag
  

To diagnose:

• Check hydraulic fluid condition and level
  
• Inspect case drain flow rate and pressure
  
• Compare motor response between left and right sides
  
• Use infrared thermography to detect heat buildup
  
• Remove and bench test the motor for internal leakage and shaft play
  

A technician in Georgia resolved a similar issue by replacing the right motor and flushing the entire hydraulic system. The original motor had failed due to a collapsed filter that allowed debris to enter the motor housing.
Repair Procedure and Component Recommendations
To repair a failed drive motor:

• Drain hydraulic fluid and remove the affected motor
  
• Inspect mounting flange and splines for wear
  
• Replace motor with OEM or high-quality aftermarket unit
  
• Flush system and replace filters and fluid
  
• Inspect and clean case drain lines and fittings
  
• Test system pressure and balance after installation
  

Recommended components:

• Bobcat OEM drive motor or equivalent from White Drive or Eaton
  
• High-efficiency hydraulic filter rated for 10 microns
  
• ISO 46 hydraulic fluid with anti-wear additives
  
• Case drain flow meter for future diagnostics
  

Preventive Maintenance and Long-Term Solutions
To prevent future motor issues:

• Replace hydraulic fluid every 500 hours or annually
  
• Change filters every 250 hours or sooner in dusty environments
  
• Inspect case drain lines during every service
  
• Monitor drive response and report any imbalance early
  
• Use fluid analysis to detect wear metals or contamination
  

Some operators retrofit their machines with magnetic filter traps to catch fine particles before they reach sensitive components. Others install pressure gauges on each motor circuit for real-time monitoring.
Real-World Anecdotes and Lessons Learned
A landscaping crew in Michigan shared how their 753 began dragging on the right side during mulch loading. After replacing the motor, they discovered the root cause was a cracked case drain fitting that restricted flow. They now inspect all hydraulic fittings quarterly and keep spare hoses on hand.
In another case, a farm operator in Oregon rebuilt their motor using a kit but experienced continued imbalance. The issue was traced to a worn control valve spool that caused uneven pressure delivery. Replacing the valve restored full performance.
Recommendations for Fleet Managers and Technicians

• Maintain a service log with motor replacements, fluid changes, and pressure readings
  
• Train operators to recognize early signs of drive imbalance
  
• Stock spare motors, filters, and fittings for field repairs
  
• Partner with Bobcat dealers or hydraulic specialists for rebuild kits and diagnostics
  
• Consider installing fluid sampling ports for regular analysis
  

For high-hour machines, consider proactive motor replacement during major hydraulic service to avoid downtime.
Conclusion
Drive motor failure in the Bobcat 753 is a solvable issue rooted in hydraulic integrity and component wear. By understanding the interaction between fluid quality, case drain flow, and motor internals, technicians can restore balance and performance. Whether grading, lifting, or hauling, a skid steer’s strength lies in its ability to move with precision—and that begins with motors that pull in harmony.