Hydraulic Power Loss in the Volvo EC140CL and Troubleshooting Strategies

[MikePhua]

The EC140CL and Volvo’s Mid-Size Excavator Legacy
Volvo Construction Equipment has long been recognized for its engineering precision and operator-focused design. The EC140CL, introduced around 2009, is a mid-size crawler excavator built for versatility in urban construction, utility trenching, and light demolition. With an operating weight near 14 metric tons and powered by a Volvo D4E diesel engine, the EC140CL features load-sensing hydraulics, electronically controlled pumps, and a refined cab interface.
Volvo’s CL-series excavators were designed to meet Tier 3 emissions standards while improving fuel efficiency and hydraulic responsiveness. Thousands of EC140CL units were sold globally, and many remain active in fleets today. However, as these machines age, hydraulic performance can degrade—especially when thermal loads rise or internal components begin to wear.
Terminology Notes

• Load-Sensing Hydraulics: A system that adjusts pump output based on demand, improving efficiency and control.
  
• Proportional Valve: An electronically controlled valve that regulates flow based on input current.
  
• PWM (Pulse Width Modulation): A method of controlling valve actuation by varying electrical signal duration.
  
• ECC (Electronic Control Circuit): The logic system that manages hydraulic pump behavior and valve commands.
  

Symptoms of Hydraulic Weakness
Operators have reported:

• Boom fails to lift unless stick is fully tucked
  
• No down-pressure even with full joystick input
  
• Tracks lack torque and stall under load
  
• Hydraulic response deteriorates as oil warms
  
• Pressure readings show imbalance between pumps
  

In one case, a 2010 EC140CL with 3,100 hours showed boom lift failure unless the stick was retracted. When extended, the boom refused to rise. Pressure readings indicated only one pump reaching 2,000 psi, while the other lagged or failed to respond.
Initial Diagnostic Path
Begin with basic checks:

• Confirm hydraulic oil level and condition (AW46 recommended)
  
• Inspect for frothing, contamination, or metal particles
  
• Check pilot pressure at operating temperature (typically 400–600 psi)
  
• Use service mode to monitor pump pressures and valve commands
  
• Verify proportional valve current ranges (usually 250–700 mA under load)
  

A technician in Alberta used VOCOM II and PTT software to access the ECC and found that proportional valves were receiving correct signals, but pump response was inconsistent. This pointed to a mechanical or hydraulic fault rather than an electrical one.
Pump and Valve Behavior Under Load
Volvo’s dual-pump system relies on synchronized output:

• Pump 1 typically handles boom and stick functions
  
• Pump 2 supports travel and auxiliary circuits
  
• If one pump underperforms, functions may stall or behave erratically
  
• Internal bypass or regulator valve failure can cause pressure loss
  

Recommended steps:

• Use hydraulic gauges to test pump output under load
  
• Inspect regulator solenoids for coil resistance and actuation
  
• Check for internal leakage using case drain flow measurement
  
• Compare commanded vs. actual pressure in service diagnostics
  

A contractor in Georgia discovered that Pump 2 was bypassing internally due to a worn regulator valve. Replacing the valve restored full pressure and eliminated boom hesitation.
Valve Block and Cylinder Interaction
If pump output is confirmed:

• Inspect main control valve block for spool wear or contamination
  
• Test cylinder seals for internal leakage using holding pressure tests
  
• Check for creep or drift when holding boom or bucket in air
  
• Clean valve cavities and replace worn O-rings and springs
  

A municipal crew in Maine found that the boom cylinder had internal leakage, causing loss of down-pressure. Repacking the cylinder restored full function.
Electrical and Sensor Considerations
While hydraulics are mechanical, control is electronic:

• Inspect wiring harnesses for abrasion or loose connectors
  
• Test proportional valve drivers for voltage stability
  
• Verify sensor calibration in service mode
  
• Check for fault codes related to ECC or PWM control
  

A technician in Oregon traced intermittent boom response to a corroded connector at the proportional valve. Cleaning and resealing the connector resolved the issue.
Preventive Maintenance and Upgrade Suggestions
To maintain hydraulic health:

• Replace hydraulic filters every 500 hours
  
• Sample oil quarterly for viscosity, water, and particle count
  
• Bleed pilot lines after service to remove trapped air
  
• Use OEM-spec fluid with correct additive package
  
• Monitor pump case drain flow annually
  

Upgrade options:

• Install pressure sensors with digital readouts for real-time monitoring
  
• Retrofit valve block with improved seals and wear-resistant spools
  
• Add thermal insulation to hydraulic lines near engine bay
  

A contractor in Texas added a hydraulic temperature sensor and discovered that oil was exceeding 70°C during summer operation. Installing a cooler reduced temperature and improved responsiveness.
Anecdote from the Field
In 2023, a land clearing firm in Pennsylvania faced sluggish boom response on their EC140CL. The operator suspected a joystick fault, but diagnostics revealed that Pump 1 was underperforming due to a regulator solenoid failure. After replacing the solenoid and flushing the system, the machine returned to full power. The owner later added a laminated pressure chart to the cab for quick reference.
Conclusion
Hydraulic weakness in the Volvo EC140CL often stems from pump imbalance, valve wear, or regulator failure. With methodical diagnostics and targeted repairs, most issues can be resolved without major component replacement. For operators who rely on precision and power, hydraulic health is not optional—it’s the foundation of every cut, lift, and trench. Regular monitoring and thoughtful upgrades ensure that the EC140CL continues to deliver performance where it counts.