Help! Strange noise coming from this part of my engine!!!

Hi

I need help before going to my dealer and ask for this part, every morning when I start the X3, I hear this weird sound like a pump running and making a weird noise. I opened my hood and tried to look were the noise was, then I saw this small part that is making noise. I took a picture of it please see and tell me what is that part of the engine. I plan to bring it at dealer this week, but you know dealers are they will ask you to replace it which that's their recommendations all the time. Hope this image can help that I took this afternoon.

Don't know about diesels, but the gas engines all have some sort of auxiliary air pump that can make a noise like you describe when it starts tocorrode inside.

On some 3 series engines (not all) it looks similar to your picture:

http://www.turnermotorsport.com/p-28...328i-330i.aspx

That's my best guess but there are of course other servo motors and pulley devices that can make a noise on startup and go away once warmed up.

Hey thanks probably it's a air pump, but what does it do for the x3?
I used to drive a 98 range rover it's kinda similar to my air pump. But the
Rover's pump Keeps trying to fill the air on the air suspension.

I just checked your link I missed it, you are right it could be a
Part for the exhaust system. And I saw the price it looks expensive
Too! Hope it's cheaper on the x3.