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Reasons for exhaustion of diesel engine exhaust and its elimination

Publisher: DTS     Release time:2018-11-23

1. Reasons for the emission of black smoke and how to eliminate it? 

This phenomenon is caused by incomplete combustion of fuel. When black smoke is emitted, the engine power is often reduced, the exhaust temperature is too high, and the water temperature is too high, which causes the engine parts to wear and reduce the engine life. The cause of this phenomenon (there are many causes of incomplete combustion) and the elimination method is as follows.

The exhaust back pressure is too high or the exhaust pipe is blocked. This situation will result in insufficient intake air, which will affect the air and fuel mixture ratio, resulting in excessive oil. This situation occurs: First, the exhaust pipe bend position (especially the 90° bend position) should be reduced as much as possible; second, the inside of the muffler should be blocked by excessive soot and should be removed.

Insufficient intake air or blocked intake pipe. In order to find out the cause, the following checks should be made: first, whether the air filter is blocked; second, whether the air intake pipe is leaking (if there is such a phenomenon, the engine will be accompanied by a harsher whistling sound due to the increase in load); Is the turbocharger damaged? The exhaust wheel and the booster wheel blade should be inspected for damage and smooth rotation; the fourth is whether the intercooler is blocked.

The valve clearance adjustment is incorrect and the valve seal line is in poor contact. Valve clearance, valve spring and valve seal conditions should be checked.

The oil supply of each cylinder of the high pressure oil pump is not uniform or too large. Uneven oil supply will result in unstable speed and intermittent black smoke, which should be adjusted to balance or within the specified range.

The fuel injection is too late, and the advance angle of the fuel injection should be adjusted.

If the injector is not working properly or is damaged, the cleaning inspection should be removed.


Injector model selection is incorrect. Imported high-speed engines have strict requirements on the selected injectors (injection aperture, number of holes, injection angle). If improperly selected, it will cause black smoke from the engine, even for the same type of engine, in different occasions. (When the output power, speed, etc. are different), the type of injector required is different. If the option is wrong, replace the injector of the correct type.

Diesel quality is poor or the grade is incorrect. The imported high-speed diesel engine equipped with a direct-injection combustor with a multi-hole injector has strict requirements on the quality and quality of the diesel fuel due to its small aperture and high precision. Otherwise, it will cause the engine to emit black smoke or even The engine is not working properly. Therefore, clean and qualified light diesel oil should be used. When diesel fuel number is recommended, use No. 0 or +10 in summer, No. -10 or No. -20 in winter, and -35 in severe cold.

The cylinder liner and piston assembly are worn more seriously. When this happens, the piston ring is not tightly sealed, and the air pressure in the cylinder is seriously degraded, so that the diesel cannot be fully burned and black smoke is generated, and the engine power is drastically lowered. In severe cases, the engine will automatically turn off when the load is carried. Wear parts should be replaced.


2.Reasons for the emission of blue smoke and how to eliminate it? 

The emission of blue smoke is caused by excessive combustion of engine oil in the combustion chamber. The reason for this failure is as follows: the oil pan and the excess oil. Excessive oil will splash into the cylinder wall with the high-speed crankshaft and break into the combustion chamber. The solution is to stop for about 10 minutes, then check the oil gauge and drain excess oil. The cylinder liner and piston assembly are severely worn and the clearance is too large. If the gap is too large, the oil will burn into the combustion chamber in large quantities, and the engine crankcase exhaust gas will increase. The treatment method is to replace the worn parts in time. The piston ring has no effect. If the piston ring is insufficiently elastic, the carbon deposit is stuck in the ring groove, or the ring ports are on the same straight line, or the oil ring return oil hole is blocked, which will cause a large amount of oil to enter the combustion chamber to burn, and blue smoke is emitted. The treatment method is to remove the piston ring, remove the carbon deposit, and re-distribute the ring ports (the upper and lower ring ports are recommended to be staggered by 180°), and replace the piston ring if necessary.

The valve and conduit clearance is too large. Due to the wear and tear, the gap between the two is too large. During the intake, the indoor oil of the rocker arm is sucked into the combustion chamber by a large amount, and the treatment method is to replace the worn valve and the conduit.
Other causes of blue smoke. If the oil is too thin, the oil pressure is too high, and the engine is not running well, it will cause the oil to burn and emit blue smoke.
Reasons for the emission of gray smoke and the elimination method? The engine exhausts the grayish white exhaust gas, indicating that some of the fuel is discharged from the exhaust pipe due to the low temperature of the machine, the poor atomization of the oil and gas, and the fuel being too late to burn.

3.The main reasons for this phenomenon:

If the injection time is too late, the injector will have a drip when it is injected, the injection pressure is too low, and the atomization is poor. When the machine temperature is too low, it is too late to burn and is discharged as white smoke. The solution is to correct the injection time and check the injector operating conditions.

Insufficient pressure in the cylinder. Due to the wear of the cylinder liner and the piston ring assembly and the poor sealing of the valve, the engine is grayed out when it is just started, and then turns into black smoke or black smoke as the machine temperature rises. The solution is to replace the worn cylinder liner, piston ring or trim valve, valve seat.

There is water in the diesel. If the engine emits gray smoke after the engine is started, as the machine temperature rises, the gray smoke still exists, it is likely that there is too much water mixed in the diesel. The solution is to open the tank drain valve and discharge the sediment and water at the bottom of the tank before starting the machine every day. In summary, the exhaust smoke anomaly is a comprehensive reflection of the internal engine failure. Therefore, whether the exhaust gas is normal or not is one of the important indicators for judging the working condition of the engine. If it can be processed in time, the ideal use of the diesel engine can be ensured and unnecessary economic losses can be avoided.



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