What causes the engine to make abnormal noise?

In general, the clicking sound of valve regulator and injector is normal in working condition. If there is an obvious abnormal sound higher than this sound, it means there is a problem.

First of all, the engine will make abnormal noise when it is working. This kind of sound is generally produced by the mixed working sound of valve regulator and injector solenoid valve. Although it sounds regular, it is still a little scattered and the sound is not particularly prominent. At present, although most vehicles use hydraulic regulators to automatically adjust the valve clearance, they still make a clicking sound, and the solenoid valve of the injector will also make a clicking sound when working, so it is normal for the engine to make these two mixed sounds when working.

Secondly, if there is a sound higher or different from this mixed beep when the engine is working, there is a high probability that something is wrong. In this case, it is necessary to carefully identify the location of this abnormal sound with the help of a stethoscope. If this abnormal noise is dull, the frequency increases with the increase of engine speed, which is probably caused by the looseness of internal components of the engine, such as abnormal noise caused by the excessive gap between large and small tiles, and if there is obvious jingle when accelerating, it is the sound of the piston knocking on the cylinder, and so on. These are all abnormal noises that only occur when there is a problem.