The inner diameter of the cylinder liner is seriously worn, and its roundness or cylindricity reaches or exceeds the usage limit. Under the conventional roundness of 0.05-0.063 mm, the cylindricity reaches 0.175-0.250 mm, and the multi-cylinder diesel engine is based on the heavy-wear cylinder. The crankshaft journals and connecting rod journals are severely worn and their roundness or cylindricity has reached or exceeded the specified limits. The cylinder pressure dropped significantly, which is lower than 75% of the rated pressure. There is an abnormal noise in the cylinder and the sound of the machine still does not disappear after heating. The fuel consumption of fuel and lubricating oil exceeds the standard, the oil pressure drops, and the exhaust gas emits smoke. Difficulties in start-up, and even shutdown during operation, can not start smoothly at water temperature 60oC. The power is significantly reduced. When the throttle is at a maximum, the diesel engine emits less than 75% of the rated power. The temperature in the crankcase rises significantly, and the diesel engine vents and oil filling nozzles emit misty smoke, and the discharged exhaust gas carries oil.