Hi everyone, this is my first post and I have searched and not found any other problem like this. Please help....

I just bought a 2003 a6 2.7t with 90k -

Sometimes when I start my car, especially when its cold. I get a very weird sound coming from the engine. It almost sounds like a belt or fan turning on and grinding metal. However, after a minute or two the sound goes away. When it turns off it almost sounds like a jet engine powering down. The car still seams to run perfect so I am not sure what this is, no check engine light or warning light or anything.

Also, periodically when driving, it sounds like a loud refferee's whistle is coming from the inside of my cabin on the right side. The sound stays constant for a minute, or sometimes 10 seconds.

Any help is appreciated. Thanks for your time.

 

Jet engine sound is probably the secondary air injection pump (SAIP). When you start your car, open the hood, the sound should come from the back of the engine in the center. You should see a cylinder behind the y-pipe on the driver's side. That's it.

The loud referee's whistle is probably the HVAC fan. It is behind the glove box. When it happens try adjusting your fan speed and see if that makes a difference. Its a common problem and a reasonably easy fix.

 

yea it is definitely coming from the back of the engine.... should I do anything to fix this?

Also, the whistle noise does not seem to get any different with the adjustment of the fan speed. But it seems more prominent when the steering wheel is off axis. Does this make sense?

Btw, thank you so much for your quick response. This site is so helpful, you guys are awesome.

 

The SAIP is just an emissions thing. Will not really affect your performance and recently another member on here posed the opinion that if "its still making noise, it must be working". It is kind of an expensive part to buy and replace (~$400 new). I've seen a few write ups of people taking it apart and cleaning it to get a bit more life out of it. There are also some options for just removing it and not replacing it, but this can lead to emissions issues. I've learned to live with mine the way it is.

Click Here for a Picture of the SAIP

As far as the whistle noise you described, I know that when mine makes that noise it is definitely the HVAC fan and yes sometimes it happens when I'm turning. Of course my definition of the referee whistle noise and yours may be completely different. A lot of people describe it as a bird whistle/chirping noise as well.

Please keep in mind with both these issues I am just guessing. However, my guesses are based on common problems that most of us have/had.

Good luck and please keep this thread updated on your findings.