The horsepower of the diesel engine decreased, the consumption of diesel oil increased, the oil consumption was severe, the parts were worn or damaged, and the machine could not work properly. These are all signs of diesel engine failure. These signs can be manifested by the anomalies of sound, temperature, smoke, smell, and so on. The following methods can be used for maintenance. 1. The ear-listening method uses the ear to carefully discern whether the diesel engine has metal knocks and other abnormal sounds. Because the diesel engine produces abnormal sounds with many factors, and the sound produced by the same factors, but also because of the diesel engine temperature and level, the weight of the load, the speed of the diffuse and other reasons are also different. Therefore, during the inspection, according to the size of the sound, the site of the sound, the vibration program, the sound is continuous or intermittent, is sharp or purely dumb, when the speed is low, the sound is loud or the speed is high, the sound is large, and the speed is stable. When loud or loud, the sound is loud, it is clear whether the sound is heard without load or when the load is clear. Gradually grasp the law and judge the malfunction of the machine. 2. Touch and touch touch by hand, diesel engine parts temperature, high pressure tubing vibration and so on. 3. Part of the stopping method, such as the occurrence of oil failure in the diesel engine, is suspected to be caused by excessive intake of the breathing air pipe, temporarily pulling out the respiratory trachea and observing whether or not the organic oil is discharged; if the organic oil is still discharged, it means that the breathing tube is not malfunctioning, but Failure of other parts. 4. When the comparison method analyzes faults, when there is suspicion for a certain part, it can be replaced by standard parts, and whether the work conditions before and after the change of parts are changed. If there is a change, there is a problem with the replaced part, otherwise there is no problem. 5. The observation method visually observes whether the running parts of the diesel engine and the joints are loosened, the exhaust color is normal, and there is no leakage, leakage, or oil leakage. 6. When the test of contradiction is to suspect that there is a problem in one part but it cannot be affirmed, the working conditions or technical status of that part can be changed to determine the fault. If the compressive force is insufficient, inject a few drops of oil into the cylinder liner to change the compression performance. If the pressure increases, there is a problem with the piston mechanism of the cylinder sleeve; if the pressure does not increase, there is a problem with the valve mechanism.