wierd raddle when i turn engine off
 

ok so i have a 01 t&c limited runs great havent really had any major problems but lately when i turn the engine off i hear a wierd raddle from the top of the engine im not sure what is causeing it it sounds kind like the belt is slipping or somthing but i looked at it and its not at all so my thoughs were it could be the idle arm or power stering pump thats all i see on the top any experience with this would be much aprciated thanks for your time

think i found the problem i think it is the tensioner if this make sense could someone please coment