(4) Abnormal operation of piston ring:

The opening clearance is too small, causing the piston ring to break; The clearance between heaven and earth is too small, which makes the piston ring stuck; Too much carbon deposits cause the piston ring to stick to the ring groove and lose elasticity, resulting in fracture or gas leakage; The opening clearance is too large or the wear is serious, resulting in gas leakage. The gas leakage damages the lubricating oil film, resulting in high surface temperature. After the piston ring is broken, the debris is easy to fall into the piston cylinder, causing cylinder pulling and cylinder biting.

(5) Using inferior fuel:

Incomplete combustion brings more combustion residues; Severe post combustion phenomenon, causing an increase in exhaust temperature and failure to take timely technical measures; The alkaline value of cylinder lubrication is not appropriate. In addition, some diesel engines may experience prolonged overload operation, increased thermal load, overheating, expansion, or poor alignment of moving components, resulting in cylinder pulling.

The symptoms of cylinder knocking during operation of diesel generator are: from medium speed to low speed, a heavy cylinder knocking sound will be made, black smoke will be emitted from the exhaust pipe of diesel generator set, and there will be sound of gunfire or fire shooting from time to time, and the engine body will overheat. The main reasons for cylinder knocking are:

1. The fuel supply time is too early

When the piston of the diesel generator set moves upward and does not reach the specified injection position, the fuel injector starts to inject fuel, so that the fuel combustion is advanced. The high-pressure gas in the cylinder impacts the piston, making a rhythmic "click, click" sound, reducing the throttle, and the knock is obvious.

The elimination method is to adjust the fuel supply advance angle, that is, increase the gasket between the fuel injection pump and the gearbox to delay the fuel supply time until it meets the specified fuel injection time. For every 0.1mm increase in the gasket, the fuel supply advance angle can be delayed by 1.3-1.7.

2. Poor fuel combustion

Low fuel injection pressure, fuel injector dripping, poor fuel atomization, and delayed fuel supply can all cause poor fuel combustion and cause cylinder knocking. The knocking sound caused by this type of malfunction is low and hoarse, accompanied by engine overheating, black smoke, or exhaust pipe blasting, spraying fire, and other phenomena. The fuel injector should be removed for inspection and adjustment, and the fuel supply time should be adjusted. If necessary, new parts should be replaced to ensure compliance with regulations.