John Deere 310A Hydraulic System Troubles and Field Solutions

[MikePhua]

The 310A and John Deere’s Backhoe Loader Evolution
John Deere introduced the 310A backhoe loader in the late 1970s as part of its expanding utility equipment lineup. Built for trenching, loading, and site preparation, the 310A featured a robust mechanical design, a naturally aspirated four-cylinder diesel engine, and a gear-type hydraulic pump system. With an operating weight around 13,000 lbs and a digging depth of approximately 14 feet, it quickly became a staple for municipalities, contractors, and farmers.
By the early 1980s, Deere had sold thousands of 310A units across North America, and its reputation for reliability and ease of service made it a favorite among owner-operators. The machine’s open-center hydraulic system was simple but effective—until age and wear began to introduce performance issues.
Symptoms of Hydraulic Failure and Common Complaints
Operators of aging 310A units often report hydraulic problems that manifest as:

• Slow or weak boom and dipper movement
  
• Loader arms failing to lift under load
  
• Jerky or inconsistent control response
  
• Hydraulic pump whining or cavitating
  
• Fluid foaming or overheating during extended use
  
• No response from backhoe functions despite engine running normally
  

In one rural excavation job in Alberta, a 310A began losing hydraulic power mid-trench. The operator noticed the loader bucket would lift only when the engine was revved to near maximum RPM, and the backhoe boom stalled halfway through its stroke. After inspection, the root cause was traced to a clogged suction screen and a worn pump coupling.
Hydraulic System Architecture and Key Components
The 310A uses an open-center hydraulic system, meaning fluid flows continuously through the control valves until a function is activated. Key components include:

• Gear-type hydraulic pump mounted to the engine
  
• Suction screen and hydraulic filter
  
• Reservoir integrated into the loader frame
  
• Control valves for loader and backhoe circuits
  
• Cylinders for lift, tilt, boom, dipper, and bucket
  
• Return lines and relief valves to regulate pressure
  

The system operates at approximately 2,250 psi, with flow rates around 20–25 gallons per minute. Because it’s open-center, any restriction in the return path or suction side can cause cavitation, heat buildup, and erratic behavior.
Diagnostic Strategy and Step-by-Step Checks
To troubleshoot hydraulic issues on the 310A, technicians should follow a structured approach:

• Fluid Inspection
  • Check hydraulic fluid level and condition
    
  • Look for milky appearance (water contamination) or burnt smell
    
  • Replace fluid if viscosity is compromised
    
• Filter and Screen Cleaning
  • Remove and inspect suction screen in the reservoir
    
  • Replace hydraulic filter (typically spin-on type)
    
  • Flush reservoir if sludge or metal particles are present
    
• Pump Function Test
  • Listen for whining or rattling noises from the pump
    
  • Check for leaks at the pump housing or fittings
    
  • Measure pressure at test ports using a gauge
    
• Valve and Cylinder Checks
  • Inspect control valve spools for sticking or wear
    
  • Test cylinder seals by observing drift or bypass under load
    
  • Verify relief valve settings and spring condition
    
• Coupling and Drive Integrity
  

• Inspect pump coupling for wear or misalignment
  
• Ensure engine RPM matches hydraulic demand under load
  
• Replace worn couplings with OEM-grade replacements
  

In one documented case, a 310A had no loader lift due to a cracked pump shaft coupling. The pump spun freely but failed to generate pressure. Replacing the coupling and flushing the system restored full function.
Terminology Notes

• Open-Center System: A hydraulic design where fluid flows continuously until a valve is actuated.
  
• Cavitation: The formation of vapor bubbles in hydraulic fluid due to low pressure, which can damage pumps.
  
• Relief Valve: A safety valve that limits system pressure to prevent damage.
  
• Pump Coupling: A mechanical connector between the engine and hydraulic pump.
  
• Suction Screen: A mesh filter that prevents debris from entering the pump intake.
  

Preventive Measures and Long-Term Maintenance
To extend hydraulic system life:

• Change hydraulic fluid every 500 hours or annually
  
• Replace filters every 250 hours or sooner in dusty conditions
  
• Inspect pump coupling and drive shaft quarterly
  
• Flush reservoir and clean suction screen every 1,000 hours
  
• Use high-quality hydraulic oil with anti-foaming additives
  

In one municipal fleet in Ohio, implementing a preventive maintenance schedule based on these intervals reduced hydraulic failures by 40% and extended pump life by over 1,500 hours.
Final Thoughts
The John Deere 310A remains a durable and capable backhoe loader, but its hydraulic system demands attention as it ages. Weak or unresponsive functions often stem from overlooked components like couplings, screens, and valves. With methodical diagnostics and preventive care, even decades-old machines can continue to perform reliably. In the world of utility equipment, pressure is power—and clean flow is everything.