My 2009 Lancer GTS has had a squealing problem lately. Happened when I had the air conditioner on during startup. I figured, replace the belt, no problem. I had done it before on other cars, and it should be just a matter of finding the tensioner. However, while I poked around and inspected, I noticed this:


Would someone mind telling me what that part is? I'm taking a wild guess here, but it probably shouldn't look like that and could be another cause of my car's squealing.

 

your tensioner is cracked, replace it asap before it damages other components.