Here's the anomaly that's driving me almost crazy.

I shut my A4 off after running it for at least 15 minutes. Then, I'll wait about 30 min (maybe a little less). I'll then start it back up and within about 1-2 seconds, I hear this gargling sound coming from the right rear of the car. It only last about 5-10 seconds. To hear it well, you must have the radio off and the climate control fan turned down.

I can't figure it out. I even had my wife start the car and I stood right next to the fuel door. Sure enough, it started to gargle. I stuck my head in the wheel well, crawled underneath the right rear tire and I can't determine where it is coming from. I'm pretty brave huh? My wife must love me. :-)

It almost sounds like fuel that is draining back down the fuel filler neck. But how does it get up there in the first place in just 20-30 min sitting in my garage. It happens regardless if the tank is full or empty.

Has any other A4 enthusiast out there encountered such a sound?

Thanks to all that reply.

I spoke with Shumburg AUDI today in Chicago. Here is what they think it is. For you techies out there listen up. This is something you may not know about!

On the Quattro version of the A4, the gas tank is not flat. It is shaped and mounted in the A4 like an upside down U. This allows room for the drive shaft to meet the rear differential. The fuel pump is only on one side of the tank. So, how does the fuel get from one side of the tank to the side that has the fuel pump?

According to Shumburg Audi, there is an injector that picks up the fuel and sends it over to the other side of the tank (where the fuel pump is).

(WOW! Maybe is has inverted injectors and I can run it upside down. Airplanes do.)

Shumburg stated that the injector (not to be confused with a pump according to Shumburg) is probable making this sound and if the car starts and runs fine, do not worry about it.

Please feel free to comment or correct anything I may have misinterpreted. Well, that's it. Boy, I learn something new everyday about the A4.