2004 sable rattling noise under the hood

hey, i recently had my fan belt replaced on my 94 sable and now there is a rattling noise comming from the belt under the hood when the car is idling or going slow. i noticed before the belt was changed that the tensioner arm was flush with the back, now its pushed out about an inch more than it was...do you think this has to be tightened? the guy that works on my car says that it self tightens but i always thought you had to tighten it yourself. if it wasnt tightened would that be what is causing the rattling noise? any help would be apprieciated. thanks for listening the tensioner has a mechanism inside it to tighten the belt as it streches with wear and age, it could be that the old belt was stretched out from use. you should not have to mess with tightening anything when the tensioner is working properly. The tensioner itself could be what is rattling and banging around. The bearing inside it could be worn out and need replaced. They are relativley easy to replace and cheap too...Car Repair Talk's forum.