Is your Diesel Generator Set Good After Several Years

May. 30, 2022

As an emergency standby power supply, diesel generator sets are used in all walks of life in the society. The cost of a diesel generator set is not cheap. After the diesel generator set has been used for a certain period of time, the user should carry out regular inspection, maintenance and service to ensure that the working state is stable and normal. After some generators have been used for several years, the user is generally worried about its working state. How to judge whether a diesel generator set is in good working condition? Dingbo Power will analyze for you from three aspects.


The smoke exhaust color of diesel generator set


Judge the working state from the color of the waste flue gas discharged from the diesel generator set. Under normal working conditions, the smoke discharged from generator set should be colorless or light gray, while abnormal colors are generally divided into three types, namely black, blue and white. The main reason for black smoke is that the fuel mixture is too thick, the fuel mixture is not well formed or the combustion is not perfect; Generally, the blue smoke is caused by the diesel engine slowly starting to burn engine oil after a long time of use; White smoke is caused by the low temperature in the cylinder of diesel engine and the evaporation of oil and gas, especially in winter.

 Diesel Generator Set

Diesel generator working sound

Valve chamber

When the diesel engine runs at a low speed, the metal knocking sound can be clearly heard near the valve cover. This sound is caused by the impact between the valve and the rocker arm. The main reason is that the valve clearance is too large. Valve clearance is one of the main technical indexes of diesel engine. If the valve clearance is too large or too small, the diesel engine will not work normally. This sound will appear after the diesel generator works for a long time, so the valve clearance should be readjusted every 13 days or so.

Cylinder up and down

When the diesel generator set suddenly drops from high-speed operation to low-speed operation, the impact sound can be clearly heard on the upper part of the cylinder. This is one of the common problems of diesel engines. The main reason is that the clearance between the piston pin and the connecting rod bushing is too large. The sudden change of engine speed produces a kind of lateral dynamic imbalance, which causes the piston pin to swing left and right while rotating in the connecting rod bushing, making the piston pin hit the connecting rod bushing and make a sound. The piston pin and connecting rod bushing shall be replaced in time to ensure the normal and effective operation of the diesel engine.


There is a sound similar to tapping anvil with a small hammer at the top and bottom of cylinder of diesel generator set. The main reason for this sound is that the clearance between the piston ring and the ring groove is too large, which makes the piston ring knock with the piston when running up and down, producing a sound similar to tapping the anvil with a small hammer. In this case, stop the engine immediately and replace the piston ring with a new one.

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Diesel generator bottom

When the diesel generator set is running, a heavy and dull knocking sound can be heard at the lower part of the engine body, especially at high load. This noise is caused by abnormal friction between the crankshaft main bearing bush or the crankshaft main bearing and the main journal. The operation of the diesel generator set shall be stopped immediately after hearing the sound, because if the diesel generator set continues to work after the sound, the diesel engine may be damaged. After shutdown, check whether the bolts of the main bearing bush are loose. If not, immediately remove the crankshaft and the main bearing or the main bearing bush, and the technician shall measure them, calculate the clearance value between them, compare them with the specified data, and check the wear of the main shaft and the bearing Bush at the same time. If necessary, repair or replace them.

Diesel generator front cover

A howling sound can be clearly heard at the front cover of the diesel generator set. This sound comes from the meshing gears inside the front cover. The gears of each meshing gear are excessively worn, resulting in excessive gear clearance, which makes the gears unable to enter the normal meshing state. The elimination method is to open the front cover, check the gear engagement with lead or paint, and adjust. If the gear clearance is too large, the new gear must be replaced in time.


The above is the method to judge the working state of diesel generator set introduced by Dingbo power. It can be judged mainly by looking, listening and touching. Among them, the more effective and direct method is to listen to the sound. Because the abnormal sound of diesel generator is generally the precursor of fault, so the inspection work shall be carried out in time after hearing the abnormal sound to eliminate minor faults and avoid the occurrence of major faults in the future, restore diesel genset to a good working condition. If you still have any other question, welcome to contact us by email, we will answer your questions.

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