I have a whirring noise too - quite loud I must say. Started two weeks ago when the car didn't move for two days while it was raining. I had a loud whine and then it went silent. Then the whirring sound appeared a couple of days later. I thought it was the alternator bearings going south, but it's more than that..
A coworker and I checked the alternator closely a few days ago, and it's actually cracked in three pieces...
A new alternator is going in on monday...
The noise was alot louder when we checked from under the car, near the wheel. It's not east to determine which part is making the noise - it could be the tensioner, the power steering pump, alternator....
