I have never seen this in any maintenance manual: I frequently struggled with moisture in the carburetor, water in the gas tank and consequently a badly running, unreliable A4. I became quite good in disassembling and cleaning the carburetor. The last incident even overwhelmed my Raycor fuel filter and water separator that I had installed this spring as a remedy. I discovered one quart water in the fuel tank (gas).
I finally found the reason. The PO installed a 1/16" thin o-ring on the fuel fill deck cap. I believe the correct thickness of this o-ring should be 3/32" in order to seal properly. I tried 1/8" but it appears to be too thick; it prevented the cap from being flush with the deck. This o-ring is the only defense against the elements (and my water hose). >From now on I will make replacing this o-ring an annual ritual during winterizing. It costs only $1.00 per piece; a well invested amount to avoid a lot of harm and effort of a failing little o-ring. Happy winterizing to all of you, Gerhard "The Mystic" 1981, C27 Trad., Holland/Lake Michigan
