It is difficult for ordinary car owners to distinguish between faulty abnormal sound and reasonable abnormal sound. When I went to the garage to check the vehicles with abnormal noise, only nearly 20% of the vehicles really had problems. There is a difference between models equipped with turbocharged engines; Vehicles equipped with engine guards may also generate noise due to friction; Some car owners may mistake reasonable abnormal noise for vehicle failure due to their ignorance of mechanical knowledge after contacting different cars. Therefore, learn to distinguish the abnormal sound of cars and avoid wasting time and energy.
Identification method of automobile noise;
In practical work, due to the limitation of working conditions, it is difficult to measure automobile noise with special instruments, and we can only describe and compare automobile noise by judging the sound in daily life. For example, the "click" sound produced by dry friction of bearings, and the "click" sound similar to a small hammer hitting the cement floor caused by excessive valve clearance.
1, correctly distinguish normal noise from abnormal noise.
When the car is working, the vibration of various mechanisms will make various noises, but the noise does not mean that the car is faulty. In order to avoid unnecessary disassembly, it is necessary to distinguish normal noise from abnormal noise. The normal vibration sound of each system component (such as the noise on the engine surface), the impact sound of gears during gear shifting, the intake and exhaust sound with gas as the working source, and the gear meshing noise are all normal noises. Abnormal noise can be divided into slight noise, general noise and malignant noise according to its influence on automobile performance. Slight noise, such as high voltage leakage flashover noise, slight looseness noise of rolling bearing, etc. Generally, the volume is low, the wear degree of parts is not great, and there is no obvious change for a long time. This kind of fault can maintain the normal running of the car without repair.
3, in the diagnosis of abnormal car noise, should pay attention to create good auscultation conditions, try to eliminate the interference of other noise, so as not to affect the accuracy of judgment.
It is best to amplify or reduce the sound consciously, that is, to use a screwdriver or other metal bar as the sounding part of the stethoscope to amplify the sound, or to use a single tube to cut off the fire to reduce the sound to meet the needs of diagnosis. The auscultation site should be kept quiet to minimize the interference of human factors.