Diagnosing and Resolving Power Loss in Kobelco SK220 Excavators

[MikePhua]

Introduction
The Kobelco SK220 series excavators are renowned for their durability and performance. However, operators occasionally encounter issues where the machine exhibits power loss, particularly under load. This article delves into common causes of power loss in the SK220 and provides practical solutions to address these challenges.
Common Causes of Power Loss

1. Hydraulic System Issues
   • Swash Plate De-stroking: The swash plate in the hydraulic pump controls the displacement of hydraulic fluid. If the swash plate becomes de-stroked, it reduces the flow of hydraulic fluid, leading to diminished power output. This condition can result from internal pump wear or control valve malfunctions.
     
   • Clogged Filters: Hydraulic filters prevent contaminants from entering the system. Over time, these filters can become clogged, restricting fluid flow and causing power loss. Regular inspection and replacement of filters are essential for optimal performance.
     
2. Fuel System Problems
   • Fuel Contamination: Contaminants in the fuel can clog injectors and fuel lines, leading to inadequate fuel delivery and engine power loss. Implementing a comprehensive fuel filtration system can mitigate this risk.
     
   • Injector Malfunctions: Faulty injectors can disrupt the fuel-air mixture, causing engine inefficiency and power loss. Regular maintenance and timely replacement of injectors are recommended.
     
3. Electrical System Failures
   • Solenoid Valve Issues: Solenoid valves regulate hydraulic flow. If these valves malfunction due to electrical issues or wear, they can impede hydraulic function, leading to power loss.
     
   • Safety Switch Engagement: The operator's safety switch must be properly engaged to enable hydraulic flow. A disengaged or faulty switch can restrict hydraulic operation, resulting in power loss.
     

Diagnostic Steps

1. Inspect Hydraulic System
   • Check Pressure Readings: Use a pressure gauge to monitor hydraulic system pressure. Low pressure readings can indicate issues such as pump wear or filter blockages.
     
   • Examine Hydraulic Fluid: Ensure the hydraulic fluid is at the correct level and is free from contaminants. Dirty or low fluid can impair system performance.
     
2. Assess Fuel System
   • Inspect Fuel Filters: Check for clogged or dirty fuel filters. Replace them if necessary to ensure proper fuel flow.
     
   • Test Fuel Injectors: Perform a flow test on the fuel injectors to ensure they are delivering the correct amount of fuel. Replace any faulty injectors.
     
3. Evaluate Electrical Components
   • Test Solenoid Valves: Use a multimeter to check the functionality of solenoid valves. Replace any that are not operating correctly.
     
   • Verify Safety Switch: Ensure the operator's safety switch is properly engaged and functioning. Repair or replace if necessary.
     

Case Study: Power Loss Under Load
An operator reported that their Kobelco SK220 exhibited power loss when performing tasks such as digging or swinging. The engine would bog down or stall unless the operator reduced hydraulic demand. Upon inspection, it was found that the hydraulic filters were clogged, restricting fluid flow. After replacing the filters, the machine's performance improved significantly, and the power loss issue was resolved.
Preventative Measures

• Regular Maintenance: Implement a routine maintenance schedule that includes checking and replacing hydraulic filters, inspecting fuel filters, and testing solenoid valves.
  
• Monitor Fluid Quality: Regularly check the quality and level of hydraulic and fuel fluids. Contaminated or low fluids can lead to power loss.
  
• Operator Training: Ensure operators are trained to recognize signs of power loss and understand the importance of proper machine operation and maintenance.
  

Conclusion
Power loss in the Kobelco SK220 excavator can stem from various sources, including hydraulic system issues, fuel system problems, and electrical component failures. By systematically diagnosing these areas and implementing regular maintenance practices, operators can mitigate power loss and ensure their machines operate at peak performance.