Oil is an important part of lubrication and cooling, when oil problems will naturally affect the work of the engine, resulting in engine noise. When the oil viscosity is too large, oil content and oil smudges and other situations, the engine condition can not be guaranteed, easy to cause excessive friction between parts, heat dissipation and other phenomena, so the noise will become larger, in this case as long as the replacement of suitable new oil can be solved.
In fact, the noise of a knock is relatively easy to hear. It is a kind of percussion sound, and the "li li" sound is produced by successive knocks. The causes of detonation include premature ignition Angle, engine carbon accumulation, excessive engine temperature, incorrect air-fuel ratio and low octane number. So replace the gasoline with a higher octane number or an appropriate oil when detonation occurs, and check for other phenomena such as carbon deposition if the problem is not solved.
3. Inlet and exhaust pipe leakage
When there is leaking into the exhaust pipe, due to start the engine, instead of conveying gas in the intake pipe leak, or should have been in the exhaust emissions of gas leak, leading to vibration occurs, thus making noise, increasing the engine noise, this case will become weak, into the exhaust pipe shall be checked and replaced.
Three, the impact of parts sound
Engine as the heart of the car, and is not a simple place in the engine compartment, but through a lot of spare parts for stability, strengthening, noise reduction, this means that once these parts become loose, will cause the engine at boot time jitter unable to reduce or inhibit, making noise is bigger, the voice of the show is the noise of the engine itself, which also may be mixed with the sound of spare parts.
In this case, the engine compartment should be opened to check for loose connections, such as the engine cover, the rubber pad of the engine support, and the intake pipe. In case of loose connections, it is only necessary to reinstall and stabilize them.