What are the causes of abnormal noise in Xichai engines?

[StVivian]

Here is a detailed introduction to the causes of abnormal noise in Xichai engines:1. Valve noise: During idle, apply a slight throttle and observe if the frequency changes. If the frequency remains unchanged, it is the sound of the solenoid valve; if the frequency changes, it is valve noise.2. During startup: When the car is cold started, the engine noise is slightly louder than when the engine is warm. As long as the sound is uniform, smooth, and not harsh, there is no problem. This is because, during a cold start, the gap between the cylinder wall and the piston has not yet reached the optimal size, and the lubrication from the engine oil is insufficient. When the engine block temperature reaches around 95 degrees, the sound will return to normal.3. Engine oil issues: Poor-quality engine oil, prolonged lack of oil changes, or insufficient oil can increase friction between the valves and guides, as well as hydraulic lifters, causing various noises in the engine to become louder.