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What are the causes of the failure of diesel generator sets exhaust oil fumes blue smoke?

June 29, 2022
In general, the diesel generator set fuel completely burned by the smoke color should be light gray, slightly heavy load for dark gray, but due to a variety of fault reasons, diesel generator sets sometimes appear exhaust white smoke, blue smoke and black smoke phenomenon. Diesel engine exhaust with blue and white smoke, generally oil vapor. This is a large amount of oil into the cylinder, the heat evaporation surface is not burned as a result. If the oil is burned, it should smoke black. Usually in the case of diesel engine chassis or oil circuit without oil leakage, resulting in increased oil consumption, exhaust blue smoke common causes are as follows:
(1) oil specifications are not correct or too much oil sump
To commonly used diesel engines, for example, the user should buy the oil in accordance with the specifications, if the specifications are not correct, the oil is too thin, it often causes the occurrence of exhaust oil fouling failure. In addition, the oil sump oil level is set too high, or add too much oil, so that the amount of oil more than the upper limit of the dipstick, so that the splash to the cylinder wall on the oil correspondingly increased, part of the oil will be from the piston ring gap, up to the combustion chamber, resulting in diesel engine flicker burn oil, the exhaust pipe will be blue smoke.
(2) over-lubrication of the gas distribution mechanism, valve rod and valve guide with too large clearance.
Cylinder head lubrication of the gas distribution mechanism is dependent on pressure. The structure of some diesel engines is characterized by the oil from the bearing hole of the rear camshaft, passing through the cylinder block, cylinder head and oil channel on the rocker arm seat into the rocker arm shaft, and then flowing out from the small hole on the rocker arm shaft to lubricate the rocker arm shaft and rocker arm bushing. If the amount of oil lubricating the valve rocker arm is too large, forming the oil level on the plane of the cylinder head is too high, it will make the oil flow downward into the cylinder liner through the gap between the valve stem and the valve guide. If the clearance between the valve stem and the valve guide itself is too large, the oil that lubricates the air distribution mechanism will also flow into the intake and exhaust tract along the valve stem. In the intake stroke, the oil down the intake valve guide enters the combustion chamber with the air, causing blue smoke in the exhaust, while the oil down the exhaust valve guide is discharged directly with the exhaust gas.
(3) Oil filter regulator oil return volume is too small.
In order to increase the amount of oil return, the need to control the main shaft tile oil channel. At the regulator, if the filter core of the oil passage mouth blocked to the original 1/4 to 1/3, the return valve mouth should be expanded as much as possible, while the main shaft tile oil passage hole from the original diameter of 8mm plus plug shrinkage to the diameter of 4.5mm, so it is possible to make the diesel engine oil flickering smoke situation to be improved.
(4) cylinder liner bore out of round.
Most of the cylinder liner bore out of round is produced in the assembly. For the dry cylinder liner set, if the cylinder liner bore out of roundness before assembly is in line with the requirements (i.e., not more than 0.025mm), but after assembly out of roundness is too large, even up to 0.1mm or so, is due to the cylinder body on the stop and the cylinder liner convex shoulder of the outer circle of the eccentricity is too large caused by. At this time, can be increased by the stop hole and the cylinder liner shoulder clearance to avoid. For the diesel generator set with wet cylinder liner, if the water seal ring slot on the cylinder liner and the cylinder liner installation hole is too large, or the water seal ring is not installed correctly, and the quality of the water seal ring itself does not meet the requirements, will make the cylinder liner bore out of round.
(5) piston ring deformation, sealing is not tight.
Take X2105 diesel engine as an example, the ring groove of the piston head is equipped with four piston rings. In order to improve the sealing, three air rings are used. Under the air ring, an oil ring is installed. In order to increase the pressure of the oil ring on the cylinder liner, a groove is turned on the outer cylindrical surface of the ring to form two oil scraping edges. In the bottom of the groove is milled out of 10 through the oil slit, when the oil ring with the piston along the cylinder wall movement, the oil ring of the two scraping blade will be the cylinder wall excess oil scraping down rice, through the piston ring groove bottom of the oil hole flow back to the oil pan. If the gap between the ring and the ring groove is too large, or the piston ring groove is too deep, then with the reciprocating motion of the piston, the oil will gradually be brought to the top of the first ring, near the upper stop, due to the sharp drop in speed, and is thrown into the combustion chamber combustion. Similarly, if the piston ring and the ring groove plane is not flat, it will also cause the same evil effect.
In addition, if the diesel generator set piston ring used for too long or manufacturing quality is poor, resulting in insufficient elasticity, is also one of the reasons for blue smoke, at this time, as long as the old and new rings or two rings manufactured by different manufacturers for comparison, you can find out the reason.
(6) cylinder liner and piston with large clearance.
If the cylinder liner and the piston with clearance is too large, then in the entire cylinder liner top and piston top, oil traces obvious. For the new diesel engine, the reason for the excessive clearance is mainly because the cylinder liner and piston skirt size grouping is not allowed, or the wrong grouping. For used diesel generators, it is mainly caused by cylinder liner, piston and ring wear. For the above problem, the user can solve the problem by replacing the relevant parts in time.
(7) crankshaft axial movement. Crankshaft axial movement, will cause the cylinder block bore bias grinding, clearance to one side, resulting in oil fugitive cylinder, exhaust blue smoke.
(8) no break-in time. Some users in the diesel generator after overhaul, not in accordance with the requirements of a period of break-in operation, that is, put into normal production use. At this time the moving parts (such as cylinder liner wall, piston and ring, etc.) the surface is still relatively rough. If a drive on the immediate high speed, large load operation, the relative surface will soon occur serious wear, and even the cylinder liner wall is strained. In this case, the diesel engine oil discharge blue smoke is inevitable.