I have a really bad clacking/rattling coming from my belt, I can spray belt conditioner on it and it will go away for about min. I put a new belt on and it went away for a week or so then came back. I also put a new tensioner pulley on and that was not it . The tensioner looks to be OK. The belt doesn't seem to be bouncing any more than normal either. Water pump pulley seems tight to. I cant figure out why when I spray conditioner on it that it will momentarily quit making the noise. This noise is really loud you can hear it coming down the street, I'm afraid if I don't find it I will be left stranded. Thanks

 

One of the best ways to find things like this is a stethoscope , you can find them in parts stores , they put a diaphragm with a metal rod on the end , you touch the rod to everything that the belt goes around , the loudest part is bad , then I take the part holding the rod off , put on a metal tube , to find vacuum , air & exhaust leaks .

 

Did you replace the entire belt tensioner assembly, or just it's pulley?

From the passenger's side, look and confirm proper alignment of the tensioner pulley in relation to the other pulleys. Most often, the rubber element of the tensioner assembly degrades and allows things to droop a little. This places the tensioner's pulley out of alignment with the others causing the belt to track stupid. In worst cases, the belt jumps a groove or so, chewing itself up and ultimately shredding with rather violent results.

 

I just replaced the pulley not the tensioner, I looked at the alignment it looks OK, but thats not saying it couldn't be off a little bit. I wonder if I should just replace it and see what happens? cant hurt right.