07-27-2025, 10:52 AM
One persistent problem that operators and mechanics encounter with the Komatsu D60-6 equipped with the Cummins NH 200 engine is the phenomenon known as "engine running on" or "dieseling." This occurs when the engine continues to run briefly after the ignition is turned off, which can lead to potential damage if not properly addressed. Understanding the causes and solutions for this issue is essential to maintain the reliability and longevity of the bulldozer.
What Is Engine Running On?
Engine running on refers to the combustion of fuel inside the engine cylinders after the operator has shut off the ignition. This is an abnormal condition caused by the engine continuing to receive heat or unregulated fuel, resulting in the engine “dieseling” or running without spark or fuel injection control. It was a common issue in older gasoline engines but can also occur in diesel engines under certain conditions.
In the case of the Komatsu D60-6 with the Cummins NH 200 diesel engine, running on usually signals mechanical or fuel system irregularities rather than ignition problems.
Common Causes of Engine Running On in Diesel Engines
Several factors can contribute to engine running on in diesel-powered equipment:
To diagnose the running on problem, a mechanic typically:
A Field Story: Avoiding Catastrophic Damage
An earthmoving contractor operating a Komatsu D60-6 reported frequent engine running on incidents during cold mornings. After inspection, it was found the shut-off solenoid was sticking, and carbon buildup was significant. Prompt replacement of the solenoid and a thorough engine cleaning eliminated the issue. This prevented further damage such as piston scoring and valve failure, saving thousands in repair costs.
Industry Insights and Preventive Measures
Engine running on is less frequent with modern diesel engines due to improved fuel control and emission standards. However, older models like the D60-6 still require vigilant maintenance.
Preventive steps include:
Conclusion
Engine running on in the Komatsu D60-6 with Cummins NH 200 diesel engine is a clear sign of fuel control or combustion issues. By understanding its causes—ranging from fuel injection timing errors to carbon buildup—and applying targeted maintenance, operators can prevent costly failures and extend engine life. Proactive care, especially in older machinery, remains vital for dependable and efficient operation in the field.
What Is Engine Running On?
Engine running on refers to the combustion of fuel inside the engine cylinders after the operator has shut off the ignition. This is an abnormal condition caused by the engine continuing to receive heat or unregulated fuel, resulting in the engine “dieseling” or running without spark or fuel injection control. It was a common issue in older gasoline engines but can also occur in diesel engines under certain conditions.
In the case of the Komatsu D60-6 with the Cummins NH 200 diesel engine, running on usually signals mechanical or fuel system irregularities rather than ignition problems.
Common Causes of Engine Running On in Diesel Engines
Several factors can contribute to engine running on in diesel-powered equipment:
- Carbon Deposits and Hot Spots: Excessive carbon buildup in combustion chambers or exhaust valves can create hot spots that ignite fuel prematurely, even after fuel supply is cut off.
- Incorrect Fuel Injection Timing: If fuel is injected too late or too early, it can cause uncontrolled combustion after shutdown.
- High Idle Speed or Overheating: Engines running at excessive idle speeds or under high thermal loads are more prone to running on.
- Fuel Leaks or Dripping: Leaking injectors or fuel lines can allow fuel to continue flowing after the engine is stopped.
- Faulty Shut-Off Solenoid or Valve: In diesel engines, the fuel shut-off solenoid stops fuel flow when the key is turned off. Failure here can cause fuel to continue feeding the engine.
To diagnose the running on problem, a mechanic typically:
- Checks the fuel shut-off solenoid for proper operation, ensuring it completely cuts fuel supply.
- Inspects the fuel injectors for leaks or drips that might feed fuel uncontrolled.
- Examines the combustion chamber and valves for carbon deposits or damage.
- Verifies fuel injection timing against manufacturer specifications.
- Reviews engine idle speed and cooling system performance to rule out overheating.
A Field Story: Avoiding Catastrophic Damage
An earthmoving contractor operating a Komatsu D60-6 reported frequent engine running on incidents during cold mornings. After inspection, it was found the shut-off solenoid was sticking, and carbon buildup was significant. Prompt replacement of the solenoid and a thorough engine cleaning eliminated the issue. This prevented further damage such as piston scoring and valve failure, saving thousands in repair costs.
Industry Insights and Preventive Measures
Engine running on is less frequent with modern diesel engines due to improved fuel control and emission standards. However, older models like the D60-6 still require vigilant maintenance.
Preventive steps include:
- Regular fuel system inspections and solenoid function tests.
- Periodic engine decarbonization to avoid hot spots.
- Maintaining proper engine idle speeds and cooling system health.
- Using high-quality fuel and additives that reduce deposits.
Conclusion
Engine running on in the Komatsu D60-6 with Cummins NH 200 diesel engine is a clear sign of fuel control or combustion issues. By understanding its causes—ranging from fuel injection timing errors to carbon buildup—and applying targeted maintenance, operators can prevent costly failures and extend engine life. Proactive care, especially in older machinery, remains vital for dependable and efficient operation in the field.
