Elimination Measures for Diesel Generator Set Knock

The diesel generator set will make a heavy knocking sound from medium speed to low speed during the operation, the exhaust pipe will emit black smoke, and there will be a sound of gunfire or outward fire from time to time, and the engine body will overheat, which is the symptom of knocking. Next, Starlight will briefly analyze the causes and troubleshooting of cylinder knocking.

The main causes of cylinder knocking are:

1. The fuel supply time is too early

When the piston of the diesel generator moves upward and does not reach the specified injection position, the fuel injector starts to inject oil, which makes the fuel burn ahead of time. The high-pressure gas in the cylinder impacts the piston and makes a rhythmic "tap, tap" clear knocking sound. The knocking sound is obvious when the throttle is reduced.

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 to the specified fuel injection time. The oil supply advance angle can be delayed by 1.3 - 1.7 for every 0.1 mm increase in the gasket.

2. Poor fuel combustion

Low fuel injection pressure, fuel injector dripping, poor fuel atomization and too late fuel supply will cause poor fuel combustion and cause cylinder knocking. The knocking sound caused by this kind of fault is low and hoarse, accompanied by engine overheating, black smoke, or exhaust pipe blasting, fire and other phenomena. The fuel injector shall be removed for inspection and adjustment, and the fuel supply time shall be adjusted. If necessary, new parts shall be replaced to make it meet the requirements.

3. The oil outlet valve is worn

After the oil outlet valve is worn, on the one hand, the clearance between the pressure reducing ring belt and the inner hole of the valve seat becomes larger, the sealing becomes worse, and the pressure reducing effect becomes worse; On the other hand, the residual pressure in the high-pressure fuel pipe is too high, and the fuel supply increases, causing fuel deflagration and knocking. The knocking sound is particularly obvious when the throttle is reduced. The elimination method is to replace the oil outlet valve and valve seat. It is necessary to remind the operator that the diesel engine in good technical condition will sometimes make rhythmic knocking sound when running at low speed. This is caused by the vibration wave caused by the sharp increase of air flow pressure during the fuel combustion process. The downstream is the aforementioned knocking.

To sum up, because the working environment, working load and the level of operators of diesel generator sets are different, the causes of cylinder knocking are various, and the elimination methods are also different. Starlight reminds everyone that we must reasonably analyze the causes and apply the right medicine to the case, so as to ensure the normal operation of the generator unit.

Starlight Power was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, please feel free to send email to sales@dieselgeneratortech.com we will pay highly attention on your question.