After long-time use, the self feeding mixer will inevitably be damaged, and the engine may also be damaged. Under what circumstances should the engine be overhauled? Let me give you a detailed introduction.

1.圆柱体的内径磨损太多，圆度偏差为0.04-0.06 mm，圆柱度偏差为0.08-0.12 mm（通常，差异由圆柱体的下半部分和上半部分测得）。对于多缸发动机，圆度和圆柱度偏差基于磨损的气缸。

1. The inner diameter of the cylinder is worn too much, the roundness deviation is 0.04-0.06 mm, and the cylindricity deviation is 0.08-0.12 mm (generally, the difference is measured by the lower and upper parts of the cylinder). For multi cylinder engines, roundness and cylindricity deviations are based on the cylinder with the maximum wear.

2.机油量显着增加，机油压力下降，排气管发出浓浓的黑蓝色烟雾。

2. The amount of engine oil increases significantly, the pressure of engine oil decreases, and the exhaust pipe emits thick black blue smoke.

.混凝土搅拌车的功率已大大降低。它的高功率仅约为额定功率的60％（不包括高海拔引起的功率下降），并且其气缸压力低于标准压力的65％。

. The power of concrete mixer has been greatly reduced. Its high power is only about 60% of the rated power (excluding the power drop caused by high altitude), and its cylinder pressure is less than 65% of the standard pressure.

4.曲轴磨损太大，磨损后曲轴轴颈的圆度和圆柱度偏差超过了使用限制，或者不圆度和锥度限制在0.10 mm。

4. The crankshaft is worn too much, the roundness and cylindricity deviation of the worn crankshaft journal exceed the maximum limit, or the out of roundness and taper are limited to 0.10 mm.

5.当发动机启动或停止时，水温为50-60℃时，水温不能平稳启动。

5. When the engine starts or stops, when the water temperature is 50-60 ℃, the water temperature cannot start smoothly.

6.发动机异常噪音或异常运行，发动机在高温下运转时气缸噪音（活塞爆震），以及主轴承或连杆轴承的剧烈振动或爆震声。

6. Abnormal noise or abnormal operation of engine, cylinder noise (piston knock) when engine is running at high temperature, and violent vibration or knock of main bearing or connecting rod bearing.