Weird sound coming from engine bay - sounds like tensioner pulley out

[mpatton]

I recently started hearing this sound coming from my engine bay that sounds like a tensioner pulley or idler pulley going out. I replaced the idler pulley and that didn't get rid of it. I am about to change the tensioner pulley, but a friend of mine that has a truck just like mine said his started doing the same thing a while back and he had replaced everything and still didn't solve the problem. I posted on a site and a guy had mentioned that the problem was his exhaust manifold bolts and loosened up and that tightening them up would fix the problem, which it did.

I was just wandering if anyone here had heard about this before. And, how hard is it to tighten the bolts (hard to get to or not).