Help Identifying Noise from Engine
 

About a week ago, on a cold morning (22 deg. F), I started the A8 (4.2 FSI) in my garage and was greeted by the sound of whooshing air and loud ticking from under the hood. I had to get to the gym, so I elected to drive it the 3 miles, but I took it slow. I turned off the Air-Con and intently listened to the noises. My car has 61,000 miles.

The whooshing sound reminded me of a frozen radiator fan-clutch; it would get louder with higher RPM's. The clicking sounded like a cracked exhaust manifold (my old Toyota truck had this). Again, the noise was in sync with the engine RPM's. I know the car uses electric fans, and I'm pretty sure the manifold is fine, I'm just describing the noises I heard as best as I can.

That same day I took it to the Audi dealer, and of course I couldn't reproduce the noises. It's been over a week and the noises have not returned. My extended warranty runs out at the end of April, so I'm hoping to identify what this was and get it fixed bere that happens,

If any of you have experienced this, or even have a good guess as to what caused these two noises I would appreciate hearing about it.

Thank you.

Unfortunately I did not make a recording. Try to imagine the sound of a loud fan combined with a ticking, all synchronized to the engine RPM. That's the best way I can explain it.