Theoretically, the timing belt of the engine should be replaced every 60,000 to 654.38+10,000 kilometers. According to the general manufacturer's maintenance manual, the timing belt is one of the important parts of the engine. If the number of kilometers increases, the timing belt will wear and age. In severe cases, the engine will stop working, and in severe cases, the valve will be pushed. In addition to regular replacement according to the manufacturer's maintenance manual, we can also check the timing belt of the engine during maintenance, when the same mileage is reached. Check whether there are cracks, fuzz and abnormal wear, which can prevent the timing belt from breaking. Generally, it should be replaced regularly according to the manufacturer's requirements. Unless driving violently frequently, it will rarely break down. Theoretically, the engine timing chain is maintenance-free, that is, it does not need maintenance or replacement. Even so, there are still many brands of engine timing chains that are stretched or abnormally worn, resulting in the need to replace the chain. For example, the chain of Volkswagen engine is easy to stretch more than 654.38+ 10,000 kilometers, so some vehicles need to replace the timing chain when it exceeds 654.38+ 10,000 kilometers. The use of some inferior or counterfeit engine oil leads to abnormal wear or abnormal noise of the engine chain, which is also one of the reasons why the engine chain needs to be replaced. Some also ran about 6.5438+10,000 kilometers due to design defects or material defects, and the chain was lengthened, abnormal wear or abnormal sound caused the need to replace the engine chain. Theoretically, there is no need to replace the timing chain, but it depends. The advantage of timing chain is that it is more durable than ordinary belt and basically maintenance-free for life. The disadvantage is that the noise of timing chain is much louder than that of timing belt. In short, each has its advantages and disadvantages. Now most engines use timing chains. Especially now, some engines also design the timing belt in the oil. I don't know if this is progress or trouble.