Causes and Consequences of Piston Knocking Cylinder of Diesel Genset

Do you know what causes the piston of the diesel generator set to strike the cylinder? What will happen if the piston of diesel generator knocks seriously? Next, let Dingbo Power analyze it for you.

Diesel generator knocking cylinder, refers to the piston in the beginning of the work stroke moment, or the piston up, the piston in the cylinder swing, its head and skirt and the cylinder wall collision and issued by the dang dang or tada abnormal sound. If it is dang sound, mostly caused by poor lubrication of the cylinder wall, you can drop a little oil into the cylinder, and then start the diesel generator set, if the noise is reduced or disappeared, that is, the noise is indeed caused by poor lubrication. If the clatter sound, while the exhaust pipe blue smoke, is generally due to the piston and cylinder wall clearance is too large.

Causes of piston knocking cylinder of diesel generator set

(1) If this phenomenon only occurs after a cold start. When the water temperature reaches normal, it disappears automatically because the clearance between the piston and the cylinder wall is too large. When the car is cold, the piston contracts again, further increasing the clearance between the two, resulting in a noticeable knocking sound. After the engine temperature rises, the piston expands and the gap tends to normal, so the abnormal noise disappears. This situation will not cause major problems in the short term.

(2) The engine oil grade does not meet the requirements. When the diesel generator set is restarted after a long time of shutdown, the engine oil is viscous and has poor fluidity. A good oil film cannot be formed on the cylinder wall in a short time, and the piston directly collides with the cylinder wall, resulting in cylinder knock. After running for a period of time, the viscosity of the lubricating oil is normal, a layer of oil film is formed on the cylinder wall, and the abnormal noise weakens or disappears. As long as the lubricating oil is selected reasonably, and the crankcase of the diesel generator set is preheated before starting, and lubricated with mixed oil, step on the starting lever several times before starting to make the parts stick more lubricating oil, this situation can be avoided.

(3) The mixture entering the cylinder cannot burn normally, causing early combustion or deflagration, or when the diesel generator set is under no load, the sound of piston hitting the cylinder wall will be generated at the moment when the accelerator is suddenly applied. Keep the diesel generator set working at normal temperature, use gasoline that meets the octane number requirements, and properly adjust the ignition time.

(4) The piston is worn and the cylindricity error is too large. When the piston goes up, its top will hit the cylinder wall, causing severe wear between the piston and cylinder, and the gap wall between the two. It can be disassembled and inspected, and corresponding repair measures can be taken according to the situation.

(5) Due to the bending and twisting of the connecting rod, the deviation between the piston pin and the pin hole, and the non parallel axis lines between the crank pin and the piston pin, the piston can also run diagonally in the cylinder and collide with the cylinder wall. This situation can only be checked after disassembly, and the corresponding components can be replaced after diagnosis.

(6) The clearance between the piston and cylinder wall is too large.

(7) The quality of the cylinder block and ring is poor. In addition, the lubrication is poor. After the diesel generator set has operated for a period of time, the wear between the cylinder block and the piston is serious, which increases the gap between the piston and the cylinder block. At the same time, serious steps appear slightly above the first gas ring corresponding to the cylinder block, which makes the piston knock the cylinder block and make abnormal noise.

(8) The piston pin fits too tightly with the connecting rod bushing.

(9) The piston is deformed.

(10) Poor lubrication.

What will happen if the piston of diesel generator knocks the cylinder severely?

Piston knocking on cylinder will lead to high fuel consumption of diesel generator set, oil leakage, excessive oil consumption and poor economy. When the piston strikes the cylinder severely, it can also break the piston and even damage the connecting rod and cylinder block.

The abnormal sound of piston knocking occurs at the upper part of the cylinder of the diesel generator set, generally at the moment when the power stroke of the piston begins. The piston swings or moves within the cylinder, causing its head or skirt to collide with the cylinder head or wall_ It produces abnormal noise, which is characterized by: when the diesel generator set is running at idle speed, the sound is similar to that of small hammer knocking, and it is rhythmic dangdang sound, which is obvious and clear. The knocking sound changes with the temperature of the diesel generator set, and the sound is obvious at low temperature; After the temperature rises, the sound weakens or disappears. When the accelerator is suddenly increased, a continuous metal tapping sound of quack is emitted. If there is knocking on multiple cylinders, the sound will be noisy and disorderly when increasing from idle to high speed.

Dingbo Power hopes that the above content will be helpful to you. Guangxi Dingbo Power Equipment Manufacturing Co., Ltd. was established in 2006. After years of efforts, it has grown into a professional diesel generator set manufacturer. If you are interested in diesel generator sets, please contact us by email dingbo@dieselgeneratortech.com.