Brunnie

Couple of questions for you...

Is the drop immediate after you turn off the car, or does it happen after several hours of sitting? Try dousing the air bag with soapy water to see if a leak is easily detectable. I would avoid putting slime in at all costs. Come to think of it, it wouldn't be that easy to get it into the airbag in the first place.

Is your suspension level light on in the dash cluster? If it is, have you had the ECU scanned to tell what code is being thrown?

Other issues may also be happening, level sensor failure is another cause for the suspension to drop, just be sure to trouble shoot all options before you pony up for a new air spring.

Just my .02
A.

K04-S4

Drop occurs slowly starting with the rear suspension and ~24hrs to reach bottom. System pumps up with engine running.

VAG-COM scanned several times to confirm there are no stored codes.

Soapy water test confirmed one rear suspension bag is slowly leaking in two places near the bottom of the bag, both leaks outboard and closest to the wheel.

I'm sure it's been asked many times but is there any way to seal the bag leak ?

Brunnie

Not that I'm aware of. I suppose if you know exactly where the leaks are occurring you could try to externally patch them with a heavy duty rubber patch kit of some kind. I don't know how reliable that would be though, I assume that the bags are running pretty high air pressure.

Come to think of it, anybody know what psi they run?

A.