Engine Misfire and Knocking in a Volvo EC160C Excavator

[MikePhua]

The Volvo EC160C and Its Engine Platform
The Volvo EC160C is a mid-size hydraulic excavator introduced in the late 2000s as part of Volvo Construction Equipment’s C-series lineup. Designed for versatility in roadwork, trenching, and light demolition, the EC160C features an operating weight of approximately 17 metric tons and is powered by a Volvo D6E engine—a 6-cylinder, turbocharged diesel known for its fuel efficiency and emissions compliance.
Volvo CE, founded in 1832 and headquartered in Sweden, has built a reputation for operator comfort, hydraulic precision, and engine reliability. However, like any diesel platform, the D6E is susceptible to wear, fuel system issues, and combustion anomalies over time.
Terminology Notes

• Skipping: A term used to describe engine misfiring, where one or more cylinders fail to combust properly.
  
• Knocking: A sharp, metallic sound caused by abnormal combustion or mechanical interference.
  
• Injector: A component that delivers atomized fuel into the combustion chamber.
  
• Compression Loss: A drop in cylinder pressure due to valve, ring, or gasket failure.
  

Symptoms and Early Warning Signs
Operators may notice the following when the EC160C engine begins to skip or knock:

• Uneven idle and reduced power
  
• Excessive white or black exhaust smoke
  
• Audible knocking from the engine block
  
• Increased fuel consumption
  
• Difficulty starting, especially when cold
  

In one case, a contractor in Ontario reported that his EC160C began skipping during trenching work. Within hours, the engine developed a rhythmic knock, and hydraulic performance dropped significantly. The issue was traced to a failed injector that caused lean combustion and piston damage.
Common Causes of Misfire and Knocking
Several mechanical and fuel-related issues can lead to these symptoms:

• Faulty fuel injectors causing uneven spray patterns
  
• Air in the fuel lines due to loose fittings or filter changes
  
• Worn piston rings or cylinder scoring reducing compression
  
• Valve lash out of spec, leading to poor sealing
  
• Turbocharger bearing wear causing imbalance and intake anomalies
  
• Contaminated fuel with water or debris
  

A technician in Colorado discovered that a misfire in an EC160C was caused by a cracked injector nozzle. The resulting lean burn overheated the piston crown and led to a knock that mimicked rod bearing failure.
Diagnostic Strategy and Inspection Sequence
To isolate the fault:

• Perform a cylinder cut-out test using diagnostic software
  
• Check injector balance and return flow
  
• Inspect fuel filters and lines for air intrusion
  
• Conduct a compression test across all cylinders
  
• Use a borescope to inspect piston crowns and cylinder walls
  
• Check valve clearance and camshaft timing
  

If knocking persists after injector replacement, deeper mechanical inspection is warranted. A fleet manager in Texas found that a persistent knock was due to a bent connecting rod caused by hydraulic lock from water-contaminated fuel.
Repair Options and Component Replacement
Depending on the root cause:

• Replace faulty injectors with OEM-calibrated units
  
• Flush fuel system and replace filters
  
• Adjust valve lash to factory specs
  
• Rebuild or replace damaged pistons and rings
  
• Inspect and service turbocharger bearings and seals
  
• Update engine control software if applicable
  

Some EC160C engines require injector coding during installation to ensure proper fuel delivery. Always follow Volvo’s service bulletins and torque specs during reassembly.
Preventive Measures and Long-Term Reliability
To reduce the risk of engine misfire and knocking:

• Use high-quality diesel with proper cetane rating
  
• Replace fuel filters every 500 hours or sooner in dusty environments
  
• Drain water separators weekly
  
• Monitor injector performance via telematics or service logs
  
• Warm up engine fully before applying heavy load
  

A contractor in Norway implemented a fuel quality protocol and reduced injector failures by 70% across his Volvo fleet.
Recommendations for Technicians and Operators

• Keep spare injectors and seals in stock for field service
  
• Train operators to recognize early signs of misfire
  
• Use infrared thermometers to detect cylinder temperature anomalies
  
• Document engine hours and service intervals
  
• Perform annual compression and injector tests on high-hour machines
  

Conclusion
Skipping and knocking in a Volvo EC160C excavator signal serious combustion or mechanical issues that demand immediate attention. Whether caused by injector failure, compression loss, or fuel contamination, these symptoms can escalate into costly engine damage if ignored. With structured diagnostics, proper parts, and preventive care, technicians can restore performance and extend the life of this versatile machine. In the world of diesel excavation, smooth combustion is the heartbeat of productivity.