Construction Machinery Maintenance | The excavator emits white smoke/black smoke/blue smoke, what’s wrong?
Posted: Feb 5th, '25, 22:00
Environmental protection is strictly enforced. What should I do if the excavator suddenly emits white smoke/black smoke/blue smoke when working?
Black smoke
Black smoke is also called carbon smoke. The main reason for diesel engine exhaust to emit black smoke is because the mixture is too rich, the mixture is poorly formed or the combustion is incomplete. The main factors are as follows:
(1) Poor diesel quality
The cleanliness of the fuel is very important. Poor quality fuel will cause the excavator to work weakly and the engine exhaust to turn black. The use of diesel with excessive sulfur and water will cause the nozzle, oil pump and engine to be strained. In severe cases, it will cause the engine to tamper with the cylinder, causing unnecessary losses.
(2) Changes in the shape and volume of the combustion chamber
Excavator equipment, excavator price, excavator
For example: the piston is installed in the wrong position, which affects the coordination of the injector, combustion chamber and intake duct, and cannot form a good mixture, resulting in incomplete combustion.
(3) The air filter element is not replaced in time
Many engine owners do not pay much attention to the air filter element when replacing maintenance parts. They either postpone the replacement or simply forget about it. This is also one of the important reasons for black smoke.
(4) Excessive fuel supply
Excessive fuel supply causes the mixture to be too rich and incomplete combustion.
(5) Improper fuel supply advance angle
The fuel is injected into the cylinder too late, and part of the fuel is separated or discharged before it can form a combustible mixture, causing part of the fuel discharged with the exhaust gas in the exhaust pipe to be decomposed and burned by high temperature, forming black smoke that is discharged with the exhaust gas.
(6) Poor operation of the injector
Poor operation of the injector is mainly manifested in three aspects: first, poor spray quality; second, insufficient injection pressure; third, injector dripping.
(7) Improper adjustment of valve clearance
If the valve clearance is too large, the maximum valve opening will be reduced and the opening time will be shortened, resulting in insufficient intake; if the valve clearance is too small, the valve is prone to leaking, which will affect the cylinder compression force. Both situations will reduce the air ratio in the mixture and cause incomplete combustion.
(8) Fuel injector failure
Excessive fuel injection leads to incomplete combustion. Service personnel are required to perform an engine cylinder cut-off test to check whether it is caused by fuel injector wear.
(9) Insufficient compression force
After the valve, piston ring, and cylinder liner are worn, the compression pressure is insufficient. The pressure and temperature at the end of compression cannot meet the requirements, the combustion conditions of the fuel are deteriorated, and carbon smoke is easily generated.
White smoke
1. Most of the white smoke is caused by water in the cylinder. Please check whether there is water in the diesel. Generally, the white smoke is emitted for a short time after starting, and there is no problem with the engine;
2. If the excavator emits white smoke when starting, the oil is not reduced, and the excavator is also powerless, it means that the engine cylinder mattress is damaged;
3. Poor atomization of the injector and low cylinder pressure are also one of the reasons for the engine to emit white smoke. Check the injector.
Blue smoke
Blue smoke when starting a cold car: It is normal for a cold car to emit blue smoke and disappear after the car is heated, because a small amount of oil will invade the engine combustion chamber after stopping.
Continuous blue smoke after starting: 1. The diesel filter is clogged, check whether the oil type is correct;
2. The engine piston ring and valve oil seal are worn, resulting in oil in the intake or exhaust pipe, which causes the excavator to emit blue smoke;
3. The clearance between the piston and the cylinder liner is too large, causing blue smoke;
When driving the excavator, you should also pay attention to the exhaust color of the excavator to judge and analyze whether the diesel engine may fail, find the problem as soon as possible, and avoid greater losses.
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Black smoke
Black smoke is also called carbon smoke. The main reason for diesel engine exhaust to emit black smoke is because the mixture is too rich, the mixture is poorly formed or the combustion is incomplete. The main factors are as follows:
(1) Poor diesel quality
The cleanliness of the fuel is very important. Poor quality fuel will cause the excavator to work weakly and the engine exhaust to turn black. The use of diesel with excessive sulfur and water will cause the nozzle, oil pump and engine to be strained. In severe cases, it will cause the engine to tamper with the cylinder, causing unnecessary losses.
(2) Changes in the shape and volume of the combustion chamber
Excavator equipment, excavator price, excavator
For example: the piston is installed in the wrong position, which affects the coordination of the injector, combustion chamber and intake duct, and cannot form a good mixture, resulting in incomplete combustion.
(3) The air filter element is not replaced in time
Many engine owners do not pay much attention to the air filter element when replacing maintenance parts. They either postpone the replacement or simply forget about it. This is also one of the important reasons for black smoke.
(4) Excessive fuel supply
Excessive fuel supply causes the mixture to be too rich and incomplete combustion.
(5) Improper fuel supply advance angle
The fuel is injected into the cylinder too late, and part of the fuel is separated or discharged before it can form a combustible mixture, causing part of the fuel discharged with the exhaust gas in the exhaust pipe to be decomposed and burned by high temperature, forming black smoke that is discharged with the exhaust gas.
(6) Poor operation of the injector
Poor operation of the injector is mainly manifested in three aspects: first, poor spray quality; second, insufficient injection pressure; third, injector dripping.
(7) Improper adjustment of valve clearance
If the valve clearance is too large, the maximum valve opening will be reduced and the opening time will be shortened, resulting in insufficient intake; if the valve clearance is too small, the valve is prone to leaking, which will affect the cylinder compression force. Both situations will reduce the air ratio in the mixture and cause incomplete combustion.
(8) Fuel injector failure
Excessive fuel injection leads to incomplete combustion. Service personnel are required to perform an engine cylinder cut-off test to check whether it is caused by fuel injector wear.
(9) Insufficient compression force
After the valve, piston ring, and cylinder liner are worn, the compression pressure is insufficient. The pressure and temperature at the end of compression cannot meet the requirements, the combustion conditions of the fuel are deteriorated, and carbon smoke is easily generated.
White smoke
1. Most of the white smoke is caused by water in the cylinder. Please check whether there is water in the diesel. Generally, the white smoke is emitted for a short time after starting, and there is no problem with the engine;
2. If the excavator emits white smoke when starting, the oil is not reduced, and the excavator is also powerless, it means that the engine cylinder mattress is damaged;
3. Poor atomization of the injector and low cylinder pressure are also one of the reasons for the engine to emit white smoke. Check the injector.
Blue smoke
Blue smoke when starting a cold car: It is normal for a cold car to emit blue smoke and disappear after the car is heated, because a small amount of oil will invade the engine combustion chamber after stopping.
Continuous blue smoke after starting: 1. The diesel filter is clogged, check whether the oil type is correct;
2. The engine piston ring and valve oil seal are worn, resulting in oil in the intake or exhaust pipe, which causes the excavator to emit blue smoke;
3. The clearance between the piston and the cylinder liner is too large, causing blue smoke;
When driving the excavator, you should also pay attention to the exhaust color of the excavator to judge and analyze whether the diesel engine may fail, find the problem as soon as possible, and avoid greater losses.
multifunctional skid loader，Multifunctional skid steer loader attachments，Skid Steer Loader Attachments
Choose DIG-DOG for high-quality, customizable brush cutters for skid steers with fast delivery. Contact us today to discover how our superior products can enhance your land management tasks!
for more info just visit our website at www.dig-dog.com
contact # : +86 158 6218 2088
email : sales@bonovogroup.com