Automatic feeding mixer in the process of driving will appear piston knock cylinder abnormal sound, below for you to explain the automatic feeding mixer this situation judgment, and processing method.

产生活塞敲缸的主要原因有以下几个方面：活塞同气缸壁的间隙太大。WD615系列发动机活塞裙部和气缸的标准间隙为0.143-0.182，磨损极限为0.35—0.40。发动机运行一段时间后，气缸活塞产生磨损，加之润滑不好，活塞和气缸的配合间隙由于磨损而增大，并在道气环略下处出现较严重的台阶，使活塞敲击气缸发出异响。

The main reasons for piston knock are as follows: the clearance between piston and cylinder wall is too large. The standard clearance between piston skirt and cylinder of WD615 Series engine is 0.143-0.182, and the wear limit is 0.35-0.40. After the engine runs for a period of time, the piston of the cylinder is worn, and the lubrication is not good. The clearance between the piston and the cylinder increases due to the wear, and a serious step appears at the lower part of the gas ring, which makes the piston strike the cylinder and make an abnormal noise.

活塞裙部和气缸在运行一段时间以后，磨损严重，造成严重失圆而敲缸。个别连杆由于种种原因产生变形，造成活塞偏磨，间隙变大而敲缸。活塞敲缸会导致发动机燃油消耗过高、发动机窜机油、机油耗量多、经济性差。当活塞敲缸严重时，还会拉碎活塞，打坏气缸，以致于连杆断裂，打坏气缸体。

After running for a period of time, the piston skirt and cylinder are worn seriously, resulting in serious out of round and knocking cylinder. Some connecting rods are deformed due to various reasons, resulting in eccentric wear of piston, larger clearance and cylinder knock. Piston knock will lead to high fuel consumption, engine oil channeling, high oil consumption and poor economy. When the piston knocks the cylinder seriously, it will also break the piston and damage the cylinder, resulting in the fracture of the connecting rod and the damage of the cylinder block.

活塞敲缸的判断方法：

The judgment method of piston knock is as follows

(1)逐缸断油：采取逐缸断油的方法来确定敲缸的位置，如果断油某缸时，声音明显的减小或者消失，而当恢复供油时能听到明显的“嗒嗒”声，自动上料搅拌车，说明该缸活塞敲缸。

(1) Cylinder by cylinder oil cut-off: the method of cylinder by cylinder oil cut-off is adopted to determine the knock position. If the oil cut-off reaches a certain cylinder, the sound obviously decreases or disappears, and when the oil supply is restored, the obvious "click" sound can be heard. The automatic feeding mixer indicates that the piston of the cylinder knocks.

(2)为了进一步证实该缸活塞敲缸，可以将该缸的喷油器卸下来，向气缸内加入少量的CD级中增压机油(起密封作用)，再装好喷油器，自动上料搅拌车一台，发动发动机，敲击声消失或者减弱，运行一会敲击声再度出现，则是该缸活塞敲缸无疑

(2) In order to further confirm the knock of the piston in the cylinder, the fuel injector of the cylinder can be removed, a small amount of CD grade medium supercharging oil can be added into the cylinder (which plays a sealing role), and then the fuel injector can be installed. How much is an automatic feeding mixer? When the engine is started, the knock disappears or weakens, and the knock appears again after running for a while