Rattle/vibrating noise from vents?!?

[sikm3]

Hey everyone....prospective B6 S4 Avant (Tiptronic, yeah I know) buyer here with an interesting question. I've test driven 2 tiptronic S4 Avants which exhibited a strange rattle/harmonic vibration from the center vents when the engine was under hard load around 3,000 rpm. The noise wasn't terribly loud but loud enough for me to hear. The first car test driven had 23K miles and it was the louder of the two. The 2nd car had 34K and it was barely noticeable but since I knew to listen for it I was able to hear it over the road noise and the engine accelerating and in both cases the salesperson riding along could hear it once I pointed it out.

It never made this noise in neutral under hard revs, only while in drive. I also test drove a tiptronic A4 1.8T to see if it made a similar sound and it seemed fine. Any help is greatly appreciated. Thanks for looking...

[NoYerRole2]

I think you should buy the second one!

[sikm3]

But it's odd that 2 cars woudl exhibit similar behavior....just curious if this is common to this model similar to the "ventilated" headlights that's supposed to be normal.

[NoYerRole2]

your right....its doesnt seem like anything is wrong though. You might be making yourself hear it in the second one. What are the prices?

[sikm3]

Starting prices are $34K for the 1st with 24K miles and $31 for the 2nd with 35K miles. Both have balances on their original warranty.

Further research has uncovered even more cars with this issue.
It may have something to do with a down tube from the roof gutter being loose and rattling against the bulkhead/firewall? Can't be quite sure this is the actual problem tho.

[NoYerRole2]

i drive a 2005.5 S4 sedan and cant hear anything from the vents. I think your just nuts..haha.