Whirring sound....please help diagnose
 

For the past few months, my 8 has been making a whirring sound for the first minute after start-up. It gets louder/raspier at higher rpms. This happens in 30 degree or 90 degree weather; it just takes longer for the sound to go away the colder it is. The car drives fine and the sound always goes away.

Before I bring it in to the dealer, does anyone suspect it's a belt (drive, alternator)?

thanks

How many miles on the car? Those symptoms smack of a failing water pump. Have it checked out.

It's an 04 with 20K miles. Water pump, eh? Never crossed my mind. If it were the water pump i'd expect the sound to be constant and never go away.

The biggest issue when i bring it in will be reproducing the sound. The car needs to rest for at least a couple hours before it will make the noise again.

Failing water pumps typically "rattle" (maybe whirr) when the engine is cold and then quiet down as the engine warms up and "loose" metal parts (bushing and shaft) expand. You may have to leave the car overnight so that the mechs can start it cold. But, before you take it in, raise the front end of the car and look at the bottom of the water pump in the front of the engine just behind the rad fan. There's a small weep hole there. If there's a bit of coolant in the weep hole, that would be another sign of a failing water pump.

^^ Air pump....Give it a light tap if it was noisy....mine stopped making a squawking noise with the right " tap" :)

Thanks for the input all
i'll try "tapping" it to see what happens. what worries me is that the noise is relatively new.