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Analysis of diesel generator set abnormal smoke emission

Jul. 08, 2021

When the diesel generator set is working, the fuel is burned in the cylinder to produce exhaust gas and discharged out of the engine. When the generator is working normally and the fuel is completely burned, the exhaust gas mainly contains water vapor (H2O), carbon dioxide (CO2) and nitrogen (N2), and the exhaust gas is generally light gray. When the fuel is incompletely burned or the generator is not working normally, there will be harmful substances such as hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx) and carbon particles in the exhaust gas, making the color of the exhaust gas appear white, Black or blue. It can be seen that the color of diesel generator exhaust can reflect the fuel combustion status, and it can also reflect the working status of the diesel generator.

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1. Black smoke from exhaust

The black smoke in the exhaust is mainly carbon particles from incomplete combustion of the fuel. Therefore, the excessive supply of fuel in the fuel supply system, the reduction of air volume in the intake system, the poor sealing of the combustion chamber formed by the cylinder block, cylinder head and piston, and the poor injection quality of the fuel injector will cause the fuel to burn incompletely, which will cause exhaustion. The gas is smoky. The black smoke from exhaust mainly has the following reasons:

1) The oil supply of the high-pressure oil pump is too large or the oil supply of each cylinder is uneven

2) The valve is not tightly sealed, causing air leakage, and the cylinder compression pressure is low

3) The air filter inlet is blocked and the air intake resistance is large, which makes the air intake insufficient

4) Cylinder liner, piston, piston ring are severely worn

5) Injector is not working well

6) Engine overload

7) The fuel supply advance angle of the fuel injection pump is too small. After the combustion process, it moves to the exhaust process

8) Electronic fuel injection system control failure failure, etc. For the black smoke generator, it can be adjusted by high-pressure fuel pump, fuel injector injection test inspection, cylinder compression pressure measurement, intake port cleaning, fuel supply advance angle adjustment, electronic fuel injection system fault diagnosis Wait for work to be checked and eliminated.


2. White smoke from exhaust

The white smoke in the exhaust is mainly fuel particles or water vapor that are not fully atomized and burned. Therefore, any fuel that cannot be atomized or water enters the cylinder will cause the exhaust to emit white smoke. The main reasons are as follows:

1) The temperature is low and the cylinder pressure is insufficient, and the fuel atomization is not good, especially when the exhaust gas emits white smoke at the beginning of the cold start

2) Cylinder gasket is damaged, cooling water seeps into the cylinder

3) When the water content in the fuel is large, the exhaust gas emits white smoke during cold start. The disappearance of the white smoke after the generator is warmed up should be regarded as normal. If the generator still emits white smoke during normal operation, it is a fault. Check whether the cooling water in the water tank is Check and analyze abnormal consumption, whether each cylinder is working normally, whether the oil-water separator has too much water, etc., and eliminate the faulty part.

3. Blue smoke from exhaust

The blue smoke in the exhaust is mainly the result of excessive oil fleeing into the combustion chamber to participate in the combustion. Therefore, any cause that causes the oil to escape into the combustion chamber will cause the exhaust to emit blue smoke. The main reasons are as follows:

1) Piston ring broken

2) The oil return hole on the oil ring is blocked by carbon deposits and loses the oil scraping effect

3) Piston ring openings are turned together, causing oil to escape from the piston ring openings

4) The piston ring is severely worn or stuck in the ring groove by carbon deposits and loses its sealing effect

5) Install the air ring up and down, scrape the oil into the cylinder and burn it

6) The elasticity of the piston ring is not enough and the quality is unqualified

7) Improper valve guide oil packaging or aging failure, loss of sealing effect

8) Pistons and cylinders are severely worn

9) Too much oil is added, causing too much oil splashing, and the oil ring is too late to scrape off the excess oil on the cylinder wall, etc.


The above three situations are common exhaust failures. You can analyze and judge according to the above description and take corresponding measures to solve them. The Starlight generator set also reminds everyone that the blue smoke of the generator usually needs to be disassembled and inspected to find out the cause and determine the solution for troubleshooting. The exhaust smoke is blue in the cold state, but the oil consumption is normal, which is related to the fuel, that is a normal phenomenon.


Please contact us via sales@dieselgeneratortech.com if you want to get more information.

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