Why do valves make noise when hot but not when cold?

[OBriella]

The reason why valves make noise when hot but not when cold: This situation indicates that there is a gap in the valves. Solutions for valve noise: 1. Check if the engine oil is insufficient. 2. If the engine oil is normal, the valves need to be replaced. Below is relevant information about valve noise: 1. Cold start of the car: When the car has been parked for a long time and the engine is started at the same temperature as the environment. During a cold start, you may hear a "clicking" sound from the engine compartment. This abnormal noise sounds very unusual, unlike the normal operation of the car. Even some new cars may experience this during the break-in period, with the engine making loud noises when started, which normalizes after the engine warms up. 2. During a cold start of the engine, due to the thick and poor fluidity of the engine oil, there may be operational noise for a short period, and slight sounds may occur when various moving parts come into contact, which is a normal phenomenon.