Kobelco SK 120 LC 1992: Troubleshooting Startup Issues

[MikePhua]

The Kobelco SK 120 LC, a 1992 model, is a powerful and reliable machine used in various construction and excavation applications. However, like any heavy equipment, it can sometimes experience startup issues that may prevent the engine from firing up properly. This article outlines common causes and solutions for startup problems in the Kobelco SK 120 LC, with insights drawn from troubleshooting experiences.
Common Causes of Startup Issues

1. Battery Problems
   • A weak or dead battery is one of the most common reasons for a machine failing to start. If the battery is not providing enough power, the starter motor may not function correctly, leading to a no-start condition.
     
   Solution: Check the battery voltage and condition. If the battery is undercharged, recharge it or replace it if necessary. Also, ensure the battery terminals are clean and securely connected.
   
2. Fuel System Problems
   • Issues with the fuel system, such as air in the fuel lines, clogged fuel filters, or problems with the fuel pump, can prevent the engine from starting.
     
   Solution: Inspect the fuel system for any visible damage or leaks. Replace the fuel filter if it's clogged, and check the fuel pump for proper operation. Bleed the fuel system to remove any air pockets.
   
3. Glow Plug Malfunction
   • The glow plugs in the engine are crucial for warming the fuel-air mixture during cold starts. If one or more glow plugs fail, the engine may struggle to start or not start at all, especially in colder conditions.
     
   Solution: Test each glow plug to ensure they are functioning properly. If a glow plug is faulty, replace it to improve cold-start performance.
   
4. Starter Motor Issues
   • A faulty starter motor can cause the engine to fail to start, even if the battery is fine. Starter motors can wear out over time, and when they fail, the engine may not turn over at all.
     
   Solution: Inspect the starter motor for signs of wear or damage. If necessary, have the starter motor tested and replaced to restore proper operation.
   
5. Wiring or Electrical Faults
   • Electrical issues, such as loose or corroded wiring connections, can prevent the machine from starting. Poor electrical contacts can interfere with the ignition system, preventing it from supplying the necessary power to start the engine.
     
   Solution: Check the electrical wiring and connections for corrosion, damage, or loose connections. Clean and secure any problematic connections.
   
6. Safety Switches or Relays
   • Many machines, including the Kobelco SK 120 LC, have safety switches or relays that prevent the engine from starting if certain conditions aren’t met (e.g., the parking brake not being engaged or the transmission not being in the correct position).
     
   Solution: Check all safety switches and relays to ensure they are functioning properly. Refer to the machine’s manual to verify the correct position for the transmission and ensure all safety systems are activated.
   

Additional Diagnostic Steps

1. Check for Error Codes
   • If the Kobelco SK 120 LC has an onboard diagnostic system, check for any stored error codes that may provide insight into the cause of the startup problem. Error codes can help pinpoint issues related to the electrical system, sensors, or other critical components.
     
   Solution: Use a diagnostic tool to read any stored error codes. Based on the codes, investigate further into the indicated system or component.
   
2. Inspect the Engine Control System
   • The engine control system plays a crucial role in managing engine startup. If there's a malfunction within the system, such as a faulty sensor or ECU issue, the engine may not start.
     
   Solution: Perform a thorough inspection of the engine control system, including sensors, wiring, and the ECU. If any components appear to be malfunctioning, replace them to restore proper function.
   

Preventive Maintenance Tips

1. Regular Battery Maintenance
   • Keeping the battery in good condition is essential for reliable starting. Regularly check the battery’s charge and condition, especially in colder weather when batteries are more likely to fail.
     
   Tip: Clean the battery terminals and ensure the battery is fully charged before operation.
   
2. Fuel System Checks
   • Regularly inspect the fuel system for leaks or clogs to prevent fuel-related starting issues. Replacing the fuel filter as part of a regular maintenance routine can help avoid these problems.
     
   Tip: Replace the fuel filter every 500-1000 hours of operation to keep the fuel system in top condition.
   
3. Check and Maintain Glow Plugs
   • Regularly check the glow plugs for proper operation. Since they are essential for starting in cold conditions, faulty glow plugs can lead to starting problems.
     
   Tip: Test the glow plugs annually, especially if operating in colder climates.
   
4. Keep the Electrical System Clean
   • Corrosion and dirt can build up on electrical components, preventing them from functioning properly. Regular cleaning and inspection of the electrical system can prevent many startup issues.
     
   Tip: Use electrical contact cleaner to keep connections free of corrosion.
   

Conclusion
The Kobelco SK 120 LC 1992 model is a robust machine, but like any heavy equipment, it can experience startup problems due to a variety of issues. By understanding the common causes such as battery problems, fuel system issues, glow plug malfunctions, and electrical faults, operators can troubleshoot effectively and get their equipment back to work quickly.
Regular maintenance and inspection are key to preventing these problems and ensuring the Kobelco SK 120 LC operates efficiently. By following the suggested solutions and performing preventative checks, operators can minimize downtime and keep the machine running smoothly.