Finally figured out the noise (sounded like a Canadian goose). It started really soft and I thought it was mechanical in drive train. Over 3-4 weeks, the goose became loud. Found info searthing forums that it was the PCV valve. (weirdest, most expensve PCV known to man).

My local NAPA had it at $134. (WTF?) Threads in forum posts cautioned not to buy a "cheap" one so I bypassed a sites offering valve at about $25. There was one on FCP Euro labeld "OEM" and I bought it.

Installation was a 20 minute job. Starting up after replacement and goose was gone. However, within a few days the honk is back, very soft at first, but getting louder.

Of note my 05 A8 has over 200K miles but runs perfectly. I bought it 6 months ago and have complete maintenence records. Digging through them, I see the pcv was changed 15K ago. Would like to talk to PO, but he is dead. (bought car from estate). Incidently, he always drove like an old mane, cause he was an old man.

Research seems to indicate the breather system might be gunked up with oil residue, et. (There is absolutly no oil leaks on my garage floor). I haven't pulled any of the breather hoses but from what i can see, there are no broken/torn hoses.

Digging through old posts on several forums indicate the breather system and PCV problems might cause engine seals leak. Records indicate that cam seals, cam chain tensioner, valve covers, etc were all replaced during last timing belt service, also at about 15K miles ago.

Another site suggested I pour some engine crankcase cleaner, run for 15 minutes and drain and refill and do do this several times. My oil was just changed a couple weeks ago and I don't own an oil well. (FYI, all records going back about 100K, indicate synthetic has always been used in car.

Any ideas what would make a PCV valve fail so quickly and what solution might be?