My Fiance has a 2003 325i and it started having a squeaky noise coming from the engine compartment. You can mostly hear it when it is idling. So from my research sounds like it is a belt tensioner, it probably has the mechanical one, but I have not been in there to see yet. I see that most people convert over to the hydraulic one. My question is this: what is the best way to go about fixing it. First off I see at my local Autozone have a replacement for the mechanical one that has a one year warranty and says it is improved from the original one. Would this be a good option. The problem is that I would go with the conversion but I dont know where or how much that will all cost. Right now with getting married I dont have a lot of extra cash. And if it is a good option to go with the autozone one since it is only $54.