buzzing engine noise. Help!

[heiwaz]

Hello, I started to hear a buzzing sound, I think was the belt tensioner or any accesory (water pump, alternator,..) bearing of the belt, I checked all of them and the belt and is OK. I haven't discovered where side the noise come, I only hear inside the engine.

What do you think is?

you can see a video I've recorded:

http://www.youtube.com/watch?v=p85bzy-3Mjg

[extanker]

remove the belt then start the motor for a short time while listening. if noise is gone shut motor off and feel all the pulleys for play

[Lucky]

^--- what he said. Definitely sounds like an accessory -- my bet is alt. Don't run the engine for more than 30 sec without the belt... But you probably knew that already.

[heiwaz]

I started the motor without the belt, but the noise still go on.

[extanker]

try unscrewing oil fill cap while engine is making noise

[heiwaz]

Why should I try this? if I remove the oil fill cap, the noise dissapear and why?

Unfortunately at the moment is impossible to try this, because I have doing the IMS upgrade, and the gear box and clutch is out of the engine. But I want to take advantage of this dissasembly to give a solution to this noise.