一、Cylinder wear    

1.There is a clear tap sound during cold start, the temperature decreases, the sound weakens disappears.

2. Cylinder pressure is low.

3. Sometimes the exhaust pipe discharges blue smoke, the oil filling port emits blue smoke.

4. The engine power performance is reduced. 

5. Add fuel consumption.ault diagnosis cleaning of cylinder wear

二、Wear rule reason of cylinder      

1. Cylinder wear rule

the vertical section of the cylinder (along the cylinder axis direction): irregular "cone" "cone" with large up small down. Worn part: the cylinder wall corresponding to a piston ring when the piston of piston type cylinder is located at the top dead center, the upper port that the piston ring cannot contact is free of wear, forming the "cylinder step". Under special conditions, the larger part of cylinder wear is in the middle (waist drum). In the same engine, the wear condition of different cylinders is the same. The wear of the front wall the back wall of the first cylinder of the common water-cooled engine is more serious. the cross section of the cylinder, the wear is uneven, the wear is irregular ellipse. The worn parts of each cylinder along the circumference direction: generally, the left side near the cylinder wall on the opposite side of the intake valve is worn greatly.    

2. Causes of cylinder wear

Under normal condition, the wear of the cylinder in the piston ring moving area along the task surface is an irregular cone with large height small height. The worn part is the cylinder wall corresponding to a piston ring when the piston is at the top dead center position. The upper port of the piston ring which is in contact with the cylinder wall does wear out forms a distinct cylinder shoulder.

The reasons for the big up the small down:

1.Mechanical wear: when the piston is located at the top dead center, the low-temperature gas burst pressure is relatively large, which causes the positive pressure of the piston ring on the cylinder wall to increase, the friction force to increase, the lubricating oil film to be damaged, the cylinder wall corresponding to a piston ring is most seriously worn.

2. Corrosion wear: organic acid acid oxide formed by mixture quenching (mineral acid formed by dissolving in water). It will corrode the surface of the cylinder form corrosion wear. The upper part of the cylinder block can be completely covered by the lubricating oil film, the corrosion effect is more more serious.

3. Abrasive wear: dust in the air, mechanical impurities in the lubricating oil, wear debris in the engine enter the cylinder wall to form abrasive wear. The dust in the air is absorbed into the upper part of the cylinder, which has sharp edges corners, so the upper part of the cylinder is also worn greatly. The reason of waist drum shape: in the area with severe sandstorm, a small amount of dust enters the cylinder, because the piston moves faster in the middle of the cylinder, the abrasive wear is the most serious

三、 Diagnosis method of cylinder wear

1. Check the pressure of defective cylinder. 

2. Check the cylinder diameter cylindricity.