Troubleshooting Slow and Weak Hydraulics on a Hitachi EX60 Excavator

[MikePhua]

Introduction to Hydraulic Issues in Excavators
Hydraulic performance is critical for the smooth operation of excavators like the Hitachi EX60. When hydraulics become slow or weak, it drastically reduces productivity and can lead to further mechanical damage. Diagnosing and fixing these hydraulic issues requires an understanding of the system components, potential failure points, and effective troubleshooting techniques.
Symptoms of Slow and Weak Hydraulics

• Reduced speed in boom, arm, or bucket movements
  
• Loss of power when lifting or digging
  
• Hesitation or lag in hydraulic functions
  
• Unusual noises such as whining or knocking from the pump or valves
  
• Overheating of hydraulic fluid or components
  

Key Hydraulic Components to Inspect

• Hydraulic Pump: Supplies pressurized fluid to the system; wear or damage reduces flow and pressure.
  
• Hydraulic Valves: Control fluid direction and flow; sticking or leakage causes sluggish operation.
  
• Hydraulic Cylinders: Convert fluid pressure into mechanical movement; internal leaks can reduce force.
  
• Hydraulic Hoses and Fittings: Carry fluid; leaks or blockages decrease system efficiency.
  
• Hydraulic Fluid: Proper level and condition are vital; contaminated or degraded fluid affects performance.
  
• Filters: Remove contaminants; clogged filters restrict flow and pressure.
  

Common Causes of Slow and Weak Hydraulics on Hitachi EX60

• Worn or damaged hydraulic pump causing loss of displacement or pressure
  
• Internal leakage in hydraulic control valves leading to reduced flow
  
• Air trapped in the hydraulic system causing spongy or slow response
  
• Low hydraulic fluid levels or poor fluid quality
  
• Clogged or dirty hydraulic filters restricting fluid flow
  
• Damaged or kinked hoses limiting flow
  
• Malfunctioning pressure relief valves causing pressure drops
  

Step-by-Step Troubleshooting Procedure

• 1. Check Hydraulic Fluid Level and Condition
  • Verify the hydraulic fluid is at the recommended level using the dipstick or sight gauge
    
  • Inspect fluid color and smell for contamination or overheating signs (dark color, burnt odor)
    
• 2. Inspect Filters and Replace if Necessary
  • Examine hydraulic filters and replace clogged ones to restore flow
    
  • Use manufacturer-approved filters to maintain system integrity
    
• 3. Examine Hoses and Fittings
  • Look for visible leaks, cracks, kinks, or bulges in hoses
    
  • Tighten loose fittings and replace damaged hoses
    
• 4. Bleed the Hydraulic System
  • Remove trapped air by bleeding the system according to the Hitachi EX60 service manual procedures
    
  • Air in the system can cause slow or erratic hydraulic movements
    
• 5. Test Hydraulic Pump Output
  • Measure pump pressure and flow with a pressure gauge and flow meter
    
  • Compare readings against specifications; low pressure or flow indicates pump wear or failure
    
• 6. Inspect Hydraulic Control Valves
  • Test for proper operation and leakage; valves may need cleaning, rebuilding, or replacement
    
  • Check for sticking spools or worn seals causing internal bypass
    
• 7. Evaluate Hydraulic Cylinders
  • Look for external leaks and test for internal leaks by applying pressure and checking for movement loss
    
  • Replace or rebuild cylinders if seals or pistons are worn
    
• 8. Check Pressure Relief Valves
  • Ensure valves open at correct pressure and do not leak excessively
    
  • Faulty relief valves can lower system pressure and reduce hydraulic force
    

Hydraulic Terminology and Concepts

• Hydraulic Pump: Converts mechanical power to hydraulic energy by pressurizing fluid.
  
• Control Valve: Directs flow to actuators, controlling movement and speed.
  
• Actuator (Cylinder): Converts hydraulic energy back to mechanical force.
  
• Pressure Relief Valve: Safety device to prevent system pressure from exceeding limits.
  
• Internal Leakage: Fluid bypassing seals inside components, reducing efficiency.
  
• Bleeding: Removing air trapped in hydraulic lines.
  

Case Study: Resolving Slow Hydraulics on a Hitachi EX60
A contractor operating a Hitachi EX60 reported slow boom and bucket movements despite adequate fluid levels. Initial inspection revealed a heavily clogged hydraulic filter restricting fluid flow. After replacing the filter and bleeding the system to remove trapped air, hydraulic performance improved substantially. Further tests showed mild pump wear; a pump rebuild was scheduled during routine maintenance to prevent recurrence. This case highlights the importance of preventive maintenance and proper filtration.
Additional Tips for Maintaining Hydraulic Performance

• Use only manufacturer-specified hydraulic fluid to ensure compatibility.
  
• Replace hydraulic filters regularly, especially in dusty or harsh environments.
  
• Monitor fluid temperature to avoid overheating, which degrades fluid and seals.
  
• Inspect hoses and fittings periodically for early signs of wear or damage.
  
• Address unusual noises or sluggishness promptly to prevent further damage.
  
• Keep a detailed maintenance log to track hydraulic system health over time.
  

Summary List

• Slow and weak hydraulics result from pump wear, valve leakage, air in system, or fluid issues.
  
• Check fluid levels, condition, and filters first.
  
• Inspect hoses and fittings for leaks or damage.
  
• Bleed the system to remove air causing sluggish response.
  
• Test pump pressure and flow against manufacturer specs.
  
• Diagnose control valves and cylinders for leaks and proper operation.
  
• Verify pressure relief valve function.
  
• Preventive maintenance is key to reliable hydraulic performance.
  

Conclusion
Diagnosing and repairing slow and weak hydraulic systems on the Hitachi EX60 excavator requires a methodical approach focusing on fluid condition, filtration, pump function, and valve integrity. Many issues stem from preventable causes like clogged filters or trapped air, but worn components such as pumps or cylinders may require replacement or rebuilding. Maintaining a clean, well-serviced hydraulic system ensures efficient excavator performance, minimizing downtime and repair costs on demanding job sites.