Humming/whirring sound from area of engine belt

[meng-chieh]

Hi guys,

I have a 2002 Camry V6 now at 5,5000 Km.

Just about a week ago I suddenly noticed one afternoon that a kind of humming or whirring sound is coming from the engine compartment whenver I accelerate. At first it was quite loud, and the sound stays for 1-2 seconds whenever I step on the gas, but lately it's been a lot more quiet, although always there (1-2 seconds interval, still). I went into the shop and after countless hours of inspection, they told me that they couldn't find anything wrong, although they think that it may be the engine belt that requires replacing (btw, they can't seem to even hear the sound that I'm hearing).

What do you guys think is wrong?

Edit: the sound is actually always there after popping the hood, it's quite faint so I couldn't hear it in the car except during low acceleration...

[csaxon]

TSB EGO40-04 Accessory drive belt squeal/belt tensioner rattle. Newer updated tensioner part #16620-28011