On this issue, it is difficult for ordinary car owners to distinguish which are faulty abnormal noises and which are reasonable abnormal noises. When I went to the garage to check the vehicles with abnormal noise, only nearly 20% of the vehicles really had problems. There must be a difference between the sounds of turbocharged engines and naturally aspirated engines. Vehicles equipped with engine guards may also generate noise due to friction; Some car owners, after coming into contact with different cars, are likely to sound their cars because they don't understand mechanical knowledge, so as not to waste 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.
The vibration of various mechanisms in the automobile will produce various noises, but the noise does not mean that the automobile is faulty. In order to avoid unnecessary disassembly, it is necessary to distinguish the normal ringing noise, such as intake noise, exhaust noise, gear meshing noise with gas as the working source, etc. 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 amplify the sound by using a screwdriver or a single cylinder to cut off the fire, so as to meet the needs of diagnosis. The auscultation site should be kept quiet to minimize the interference of human factors.