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Fault Analysis of Exhaust Smoke Color of Diesel Engine

Views: 74     Author: Site Editor     Publish Time: 2020-06-22      Origin: Site

Fault Analysis of Exhaust Smoke Color of Diesel Engine

Fault Analysis of Exhaust Smoke Color of Diesel Engine

The application range of diesel generator sets in hospitals, hotels, hotels, real estate and other industries is expanding. When purchasing generator sets used in different sites, one of the matters to be noted is the choice of unit power. For example, whether it is 227KW 4 stroke diesel engine or 660KW high speed diesel engine generator set,  when the smoke exhaust of these generators is abnormal, follow the instructions below Analyze the reasons.


Earlier, we analyzed the symptoms and causes of black smoke emitted by high speed water cooled simple diesel engines(mainly because of incomplete combustion of diesel in the cylinder, some carbon elements were suspended in the exhaust gas, and black smoke appeared). The following will further understand the situation of blue smoke, white smoke and yellow black smoke emitted by diesel engines. 


Main characteristics of blue smoke from diesel engine exhaust

This situation means that excessive engine oil enters the cylinder, after burning, it evaporates into blue oil and gas without being burned, and is discharged with the exhaust gas, that is, the engine oil is burned.


The main features are that the smoke exhaustion is severe at low temperature, and the smoke emission decreases or disappears after the temperature rises; the medium and small load exhaustion is slight, and the heavy load exhaustion is serious at high speed; under the condition of various speeds, the smoke is discharged intermittently or continuously.


The main cause of blue smoke from diesel engine exhaust
The exhaust emits blue smoke. Generally, it is caused by the diesel engine being used for a long time, and slowly starts to burn engine oil. With the increase of blue smoke, more and more engine oil is burned. Therefore, you should consider repairing the diesel engine. Sometimes the fuel is mixed with water, or there is water leaking into the combustion chamber, causing a change in combustion, and the diesel will emit light blue smoke. The main factors affecting its generation are:
1. The air filter is blocked, the air intake is not smooth or the oil level in the oil basin is too high (oil bath air filter), so that the amount of air entering the cylinder is reduced, the normal proportion of the fuel mixture changes, resulting in more gas and less gas. Incomplete combustion of fuel can also cause blue smoke in the exhaust.
2. Too much lubricating oil is added in the oil pan. The crankshaft rotates at high speed to cause excessive oil, and the crankshaft rotates at high speed to cause the engine oil to splash on the cylinder wall and enter the combustion chamber.


3. Long-term low load (less than 40% of the rated power) operation, the gap between the piston and the cylinder liner is too large, so that the oil in the oil pan can easily enter the combustion chamber; mix with the fuel mixture in the cylinder to change the mixing the normal proportion of gas. If the combustion is incomplete, it will cause the exhaust to emit blue smoke, accompanied by the phenomenon of increased crankcase exhaust gas.


4. The piston ring is stuck or worn too much, and the elasticity is insufficient. When installing, the chamfering direction of the piston ring is reversed. The piston ring port is formed because each ring port is on the same line, and the oil return hole of the oil ring is blocked. A large amount of engine oil is channeled to the combustion chamber for combustion, and the blue water vapor smoke is discharged after the lubricating oil is burnt.


5. The cylinder head near the oil passage of the cylinder head is burnt, and the piston and cylinder liner are worn out, etc., which will cause the lubricating oil to enter the combustion chamber and burn with the fuel mixture.


6. The gap between the valve and the duct is too large, and the engine oil in the rocker arm is sucked into the combustion chamber in large quantities to burn, forming blue smoke.

Main characteristics of white smoke from diesel engine exhaust

Exhaust emits white smoke indicates that diesel droplets have not burned in the cylinder, and there is water in the diesel or cylinder.


The main feature is that it is difficult to start or start white smoke or white smoke similar to water vapor; when low temperature and low speed, the smoke is serious; as the temperature and speed increase, the smoke is reduced or disappears; under various speed conditions, white smoke discharged intermittently.


When the diesel engine is just started or when it is cold, the exhaust pipe emits white smoke, which is formed due to the low temperature of the 1000KW powerful diesel engine generator cylinder and the evaporation of oil and gas, especially in winter. When the diesel engine is running in cold weather, the temperature of the diesel engine and the exhaust pipe is low, and it is normal for the steam exhaust to condense into water vapor to form white smoke. If the temperature of the diesel engine and the temperature of the exhaust pipe are still normal, white smoke is still emitted, indicating that the diesel engine is not working properly, and it can be judged that the diesel engine is faulty.


The main causes of white smoke from diesel engine exhaust

1. The cylinder liner is cracked or the cylinder head gasket is damaged. As the temperature and pressure of the cooling water increase, the cooling water enters the cylinder. It is easy to form water mist or water vapor when exhausting.


2. Poor atomization of the injector, the injection pressure is too low, and there is oil dripping. The fuel mixture in the cylinder is not uniform, the combustion is incomplete, and a large amount of unburned hydrocarbons is generated, and water mist or water vapor is easily formed when exhausting.


3. Severe wear of pistons, cylinder liners, etc. causes insufficient compression force, resulting in incomplete combustion.


Main characteristics and causes of yellow and black smoke from diesel engine exhaust

The main characteristics of yellow and black smoke are: the yellow and black smoke is discharged in the middle speed stage at the initial stage of operation; after the temperature is increased or the load is increased, the yellow and black smoke is gradually reduced or disappeared, and it is easy to turn off at idle speed and the body shakes; the intake pipe "choke", the exhaust pipe fires, the diesel engine has insufficient power, and it is difficult to start.


The exhaust emits yellow and black smoke, and the diesel engine works normally. But it is not normal for the smoke color to become gray or close to black. In addition to the above reasons for black smoke exhaust, there may also be reasons for poor air intake, that is, poor air supply. When the intake air filter is removed and the exhaust smoke color changes from deep to light or even colorless, the air filter is blocked, and the cause of the poor air intake should be checked.


The abnormal smoke color is a comprehensive reflection of internal faults in the diesel engine. Timely processing can ensure the normal use of the diesel engine, improve the performance of the diesel engine, reduce the incidence of failures, avoid unnecessary economic losses, and improve the economic performance of the diesel engine.


If your diesel engine has only a small problem with smoke exhaust, then follow the above reasons to treat the symptoms. If you plan to replace it, I suggest you choose a new stationary high quality diesel engine.


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