Why should the tensioning wheel be replaced at the same time when replacing the belt, even if it is not damaged?

Both timing belts and accessory belts have a fixed replacement cycle, and even if there are no abnormalities on the surface, they often suddenly break, affecting driving safety. Therefore, it is best to replace the belt on time, especially the timing belt, as breaking it can damage the engine and result in high maintenance costs. Although a broken accessory belt will not damage other components, it cannot be driven normally and may suddenly lose power in the direction, posing a certain level of danger. Whether you go to a 4S store or a repair shop to replace it, it's not just about replacing one belt. The tensioner and idler also need to be replaced together. A belt is not

expensive for over a hundred yuan, but with a few pulleys and labor costs, the cost becomes higher. So the tightening wheel is not damaged, must it be replaced together with the belt? Can we replace it if it's broken?

Replacing together is not for the repair shop to make more money, the two need to be replaced together, just like changing the oil filter is necessary when changing the oil. The lifespan of the belt tensioner is not very long, and many cars experience situations where the belt does not break and the tensioner breaks first. Therefore, since it is a replacement of the belt, it indicates that the belt has reached its lifespan. Although the tensioning wheel is not damaged now, the remaining lifespan should not be long. Can we wait until it's broken before replacing it? It's also possible, but there is a significant risk involved. If the tensioning wheel is severely damaged, it will damage the new belt. Even if it is not damaged, it cannot drive normally, and the consequences are the same as a broken belt. Replacing the belt is to avoid breakage and eliminate hidden dangers. If the tensioning wheel is not replaced, the hidden dangers cannot be eliminated, and the significance of replacing the belt is not significant. Therefore, for safety reasons, it is best to replace the belt and pulley together. Moreover, whether to change the wheel or not is a matter of labor costs. If the belt is replaced and the wheel is broken soon after, it is necessary to change the wheel again and pay another labor cost, which wastes one's own money and time.

When the tensioning wheel is slightly damaged, it will make a creaking or rustling noise. After ignition, there will be a continuous sound. Some may make a noise when the car is cold and hot, but it will not make a sound. This may be caused by the damage to the tensioning wheel, or it may be due to the belt slipping and friction with the leather belt pulley at the end of its lifespan. There is a noise around the belt that needs to be carefully checked and confirmed, because besides the tensioning wheel, there are many other components of the belt pulley that may make abnormal noises. If there is still noise after replacing the new belt, it can be ruled out that the belt, tensioner or idler wheel are most likely to make noise.

Regarding the replacement cycle of belts and pulleys, follow the requirements in the maintenance manual. If the car is driven less, the load is not high, and the driving conditions are good, it can also be appropriately extended. The accessory belt can be roughly determined by inspection to determine if it has reached its lifespan. If there are many cracks or large burrs on it, it indicates that the lifespan has reached. The timing belt may not be accurate through visual inspection, and some broken belts do not have cracks on them. They may have broken somehow and are likely caused by aging. Therefore, the timing belt basically does not need to be inspected, and can be replaced in a timely manner after reaching the mileage. In addition, inspection is not easy as it cannot be seen from the outside, and the belt cover needs to be removed to see it.

From：WONDEE Autoparts

2024-6-19