更近有车友以直报怨为什么汽车开久了就会叽里呱啦开始响,实在受不了这个噪音了。发动机声音会出现过大的问题，不少车主都一直被这问题困扰着。究竟发动机声音大是由于什么问题造成的呢？
Recently, some motorists have been complaining about why the car starts to rattle after driving for a long time. I can't stand the noise. The engine noise will be too loud, many car owners have been troubled by this problem. What is the cause of the engine noise?
1、有积碳
1. There is carbon deposition
因为老机油越用越稀，所以积碳越来越多。机油稀了容易窜机油，造成积碳越来越多，损失了很多动力。当换上新机油时，发动机不能适应机油的粘度，可能会拉高转速，进而造成发动机噪音大。
Because the old engine oil is used more and more thinly, there are more and more carbon deposits. When the oil is thin, it is easy to shift the oil, resulting in more and more carbon deposition and loss of a lot of power. When the new oil is replaced, the engine can not adapt to the viscosity of the oil, which may increase the speed and cause the engine noise.
2、隔音
2. Sound insulation
如果在外边听着发动机运转正常，坐在车里感觉噪音偏大，说明你的车辆隔音效果差。应该检查车辆的密封条，看看有没有老化的现象。或者增加车辆的密封效果，再试试噪音如何。
If you listen to the engine running normally outside and feel the noise is too loud when sitting in the car, it means that the sound insulation effect of your vehicle is poor. The seal of the vehicle should be checked for signs of aging. Or increase the sealing effect of the vehicle, and then try the noise.
3、冷却液
3. Coolant
冷却液的作用大家都知道，当它温度太低的时候就很可能出现问题，而且发动机的噪音也会变大，这是应该检查更换，避免出现别的问题。
As we all know, when the temperature of the coolant is too low, it is likely to have problems, and the noise of the engine will increase. This should be checked and replaced to avoid other problems.
4、减震器
4. Shock absorber
大家都知道减震器的作用，一般在过减速带的时候我们就能感觉到车上的减震器好不好，当车上的减震器出现问题的时候就会出现发动机噪音大的问题。
We all know the function of shock absorbers. Generally, we can feel whether the shock absorbers are good or not when passing the speed bumps. When there is a problem with the shock absorbers on the cars, there will be a big engine noise problem.
5、爆燃爆震
5. Deflagration and detonation
出现爆震时，即火花塞跳火后，末端可燃混合气发生自燃的现象，此时火花塞点燃混合气形成的火焰与末端混合气自燃形成的新的火焰，方向相反，并以冲击的速度传播，产生尖锐的敲缸声，增大发动机噪音。
In the case of knock, that is, after the spark plug jumps, the combustible mixture at the end will spontaneously ignite. At this time, the flame center formed by the spark plug ignited mixture and the new flame center formed by the spontaneous combustion of the end mixture have opposite directions, and propagate at the speed of impact, producing sharp cylinder knocking sound and increasing engine noise.
6、心理作用
6. Psychological function
人的听力在不同的环境是有误差的，从油品粘度的技术角度分析，粘度20，30的机油在市区行驶中噪音会稍微大些，在高速正常行驶，噪音会稍小些。粘度40，50的油品在市区行驶中噪音会稍小些，上了高速正常行驶，噪音会稍大些。当然要想真正的区分噪音的大小，还得用分贝仪进行测试
People's hearing has errors in different environments. From the technical point of view of oil viscosity, the noise of engine oil with viscosity of 20 and 30 is slightly higher in urban driving, while it is slightly lower in normal driving at high speed. The oil with viscosity of 40 and 50 will make a little less noise when driving in the urban area, but it will be slightly higher when driving at high speed. Of course, if you want to really distinguish the size of the noise, you have to test it with a decibel meter
