Reasons for Excavator Emitting Blue Smoke

The main reason for the blue smoke emitted by excavators is often the mixing of engine oil into the diesel fuel, which is a prominent sign of oil burning. However, during cold starts, especially in winter when temperatures are low, a layer of engine oil adheres to the cylinders. When the excavator is started, this oil residue may burn off, resulting in a small amount of blue smoke, which is considered a normal phenomenon. Additionally, there are several other reasons and solutions as follows.

Reasons for Excavator Emitting Blue Smoke:

Check if the engine is burning oil internally. Fill the oil to the highest mark on the dipstick, let the engine cool for 30 minutes, and check the oil level several times. Also, check the oil daily before starting the engine. If the oil level noticeably decreases over a few days, it indicates oil burning and blue smoke emission.

Continuous Blue Smoke Emission May be Caused by:

1. Excessive oil level in the oil sump. High-speed rotation of the crankshaft can cause oil to splash onto the cylinder walls and enter the combustion chamber. It's important not to check the oil level immediately after the engine stops, as the oil splashed onto the crankcase walls has not yet flowed back. Wait for 10 minutes before checking.

2. Check the condition of the cylinder liner, piston, and piston rings. Severe wear and excessive clearance can cause oil to enter the combustion chamber and burn outside. If the piston is heavily worn, it should be replaced promptly. If the piston rings fail, causing a large amount of oil to enter the combustion chamber and emit blue smoke, remove the rings, clean the carbon deposits, and correctly assemble the rings. If necessary, replace the piston rings. New excavators or those recently overhauled generally do not experience oil ingress due to excessive clearance between the piston and cylinder. It is often caused by incorrect installation of piston rings, such as installing them inside out or with improper gaps. This should be checked carefully.

3. Generally, replacing piston rings can improve cylinder sealing, addressing oil burning and power deficiency issues. However, if the engine has excessive crankshaft axial clearance, resulting in significant axial movement and affecting piston operation perpendicularity, it can exacerbate piston ring and cylinder wall wear. Consequently, within a short period, the gap between the piston rings and cylinder becomes too large, and the oil burning and power deficiency problems cannot be fundamentally solved.

4. Excessive clearance between valves and guides can lead to significant oil ingestion into the combustion chamber, requiring replacement of worn valves and guides. For turbocharged engines, if blue smoke is observed along with no decrease in engine power but oil stains are visible at the air compressor outlet or intake hose, it's likely turbocharger oil leakage. Oil enters the combustion chamber with the airflow, necessitating turbocharger replacement and checking for contaminated lubricating oil, which may need replacement.

5. Check if the air filter is clogged. A clogged air filter increases resistance during cylinder intake, hindering airflow and creating negative pressure inside the cylinder, leading to oil suction into the combustion chamber. Therefore, when blue smoke occurs, the air filter should also be inspected and cleaned.

6. Using the wrong type of engine oil or changing to an incorrect oil type can also cause blue smoke emission.

In summary, blue smoke from the engine exhaust is often referred to as "oil burning," indicating engine oil entering the cylinders. During regular equipment usage, observe the equipment's performance closely, take preventive measures, and promptly address any issues related to blue smoke emission to avoid potential hazards.

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