Hi, I'm new to the forum and I was hoping someone might have some ideas to help me with my problem with my 2003 Audi A4 1.8 quatro. The problem is this, the car is making a high pitch (not too high, though) drone coming from somewhere under the rear middle of the car. The car seems to be running perfectly fine other than this noise, but obviously it has me concerned. Some other facts that might help in determining this mystery noise are: 1) it seems that the noise is most pronounced is at a cold start up; 2) it varies in both pitch and volume, again, being loudest when the car first starts up; 3) at some points, it's almost as if the the noise totally disappears, primarily after driving for a while...this could be false and the noise might still be there just masked by the other noises, i.e. it is very faint. As I sadi, the noise is definately coming from somewhere under the car, not under the hood, but it does almost have the sound of a vibrating fan. Thanks for any help.

 

exhaust leak maybe and it is louder at start up......idk

 

Exactly what I was thinking - when it's cold the piping would be slightly shrunken, aggravating the leak and noise, and as it heats up it'll start to seal itself. The points when it disappears probably are just when the pitch of the leak coincides with the pitch of the road noise combination of wind/tires/etc. Check the exhaust system for bad gaskets or loose bolts.

 

+1^^

 

Could be your combi valve gunked up. Its related to the secondary air pump and can be noisy on a cold start, almost like a metalic sounding rattle. The sound dies down and eventually goes away once the SAP has finished doing its job.The combi valve is whats used on newer EGR-less valve engines.

 

First off, thanks for the replies. To show my ignorance in car matters, though, how serious are these problems, assuming one of them is what is the matter with my car? Secondly, is this something my local mechanic down the street can handle or should I bring the car to the Audi mechanic?