A car engine consists of drive belts which run various accessories that are connected to it, such as the power steering pump, AC compressor, water pump and the alternator. However, it is important that the drive belts don’t interfere with other components and belts nearby. To guide the drive belts, an idler pulley is used to route them properly around these accessories. This keeps the engine belt rotating smoothly which ultimately sustains the entire internal function of the vehicle.
Most vehicles only need one idler pulley for the engine. In some specialized vehicles, there may be more than one idler pulley. Eventually, the time will come when the idler pulley becomes too worn out or damaged to continue functioning properly. You will notice when this occurs because there will be various symptoms that will present themselves. One easily noticeable symptom is a squealing or other strange noise coming from the engine area. This will likely be the beginning stages of idler pulley problems.
The Top 3 Causes of Idler Pulley Noise
When you hear a noise coming from the idler pulley, it can be attributed to 1 of 3 causes. Your pulley may wear out, slip, or be damaged altogether. Below is a description of each of these causes in the order that you can expect them to occur. It is important that you pay attention to the noises because they go from bad to worse. The lighter noise you hear from the first cause should be enough reason to have your vehicle checked by a mechanic. Otherwise, the noises will get worse and then lead to more serious problems which will cost you a lot more money to get fixed.
1) Pully Old and Worn Out – The idler pulley is constantly spinning along with the drive belt. This creates wear and tear on the pulley after years of doing this repeatedly. The pulley will develop scuffs and other marks on its surface when this occurs. This is when the noises will begin, although they will be smaller noises at this point.
2) Pully Slippage – Idler pulley slippage is likely to follow after it becomes too worn out. This will cause the pulley to bind and then rub against the engine belt. As a result, there will be squealing noises coming from the engine area that will only get worse until the pulley is replaced. Not only that, it may also cause other belts and components within the engine to become worn and damaged too.
3) Pully Damage – In extreme situations where the first two causes of idler pulley noise are ignored, the idler pulley will get damaged and ultimately break altogether. The pully will form cracks and start to break apart a little bit at a time. This will create a chain reaction where the drive belt becomes torn. If this happens, then you will have a lot of problems coming from the engine, like stalling and overheating. On top of that, you will have an even louder squealing noise that will be consistent and annoying to everyone in the car and the immediate surrounding area.
The cost to replace the idler pulley of your driver belt will be between $80 and $200. The cost for the new part should only be anywhere from $40 to $90, while the cost of the labor will be anywhere from $40 to $110. These prices do not include added taxes and fees charged by the auto shop. Overall, this replacement job is not that expensive to get done. Since the drive belts of the engine are dependent on the idler pulley, you cannot afford to postpone replacing this part after it gets worn out.