1. When the diesel engine has a heavy and continuous knocking sound at the lower part of the crankcase, the sound is clear and recognizable at low speed and more obvious at heavy load. The same opportunity oil pressure decreases with the decrease, which is caused by the excessive clearance of the main bearing bush of the crankshaft.

2、當發起機低速忽然改動轉速時，在氣缸上部發出“鐺、鐺”的響聲，這是活塞銷與連桿襯套、或與活塞銷座的配合間隙過大所致。

2. When the engine suddenly changes the speed at low speed, the sound of "bell, bell" will be sent out at the upper part of the cylinder, which is caused by the excessive fit clearance between the piston pin and the connecting rod bushing or with the piston pin seat.

3、當發起機高速運轉時，發出“咯噔、咯噔”悶擊聲，忽然減小油門時尤為嚴重，這是因主軸瓦軸向間隙過大所致

3. When the engine runs at high speed, it makes a "cluck, cluck" dull sound, especially when the accelerator is suddenly reduced, which is caused by the excessive axial clearance of the main shaft pad

4、當在氣缸全長部位聽到轟鳴、沉悶的“空咚、空咚”的敲擊聲，且翻開加機油口蓋時發現有氣泡（闡明有漏氣現象），這是活塞與缸套配合間隙過大所致。

4. When a loud and dull knocking sound of "empty Dong, empty Dong" is heard at the full length of the cylinder, and bubbles are found when opening the oil filler cover (indicating that there is air leakage), which is caused by the excessive matching clearance between the piston and the cylinder liner.

5、若在同一部位略靠曲軸方向聽到“嘎、嘎、嘎”的撞擊聲，則是連桿扭曲致使其在工作中搖晃的敲擊聲，后兩種聲響在改動轉速時更能明顯聽到，且較易于區別；沿氣缸上、下各處均有相似小鐵錘輕擊鐵塊的聲音，柴油機排氣管冒藍煙（伴有燒機油現象），用長柄螺絲刀抵在缸體處更易于聽出，即可判定是活塞環側隙過大或環折斷所致。

5. If the impact sound of "GA, GA, GA" is heard in the same part slightly close to the crankshaft direction, it is the knocking sound of the connecting rod shaking due to the distortion of the connecting rod. The latter two sounds can be heard more obviously when changing the speed and are easier to distinguish; There is a similar sound of small hammer tapping the iron block all over the upper and lower parts of the cylinder, and the exhaust pipe of the diesel engine emits blue smoke (accompanied by oil burning). It is easier to hear when touching the cylinder block with a long handle screwdriver. It can be determined that it is caused by excessive side clearance of the piston ring or broken ring.

6、當柴油機忽然改動負荷時，在曲軸箱左近（氣缸體中部至下部范圍內）可明顯地聽到急促的“空、空、空”鈍啞的敲擊聲，并隨負荷或轉速的增加而急劇變化，響聲增大，翻開加機油口蓋可聽得更分明，無負荷時則不明顯。這是由于連桿瓦過度磨損而形成連桿瓦與曲軸連桿軸頸配合間隙過大所致。

6. When the load of the diesel engine changes suddenly, the blunt and dumb knocking sound of "empty, empty and empty" can be obviously heard near the left of the crankcase (within the range from the middle to the lower part of the cylinder block), and changes sharply with the increase of load or speed. The sound increases. It can be heard more clearly by opening the oil filler cover, but it is not obvious when there is no load. This is due to excessive wear of the connecting rod bush, resulting in excessive fit clearance between the connecting rod bush and the crankshaft connecting rod journal.

7、若使柴油機某缸斷油，假如此異響立刻消逝，則闡明是該缸的連桿瓦響。

7. If the oil of a cylinder of the diesel engine is cut off, if the abnormal noise disappears immediately, it indicates that it is the connecting rod bush noise of the cylinder.