AudiAdventure18

Joined the forum after a few weeks of reading as much as I can about my new-to-me C7 A6.

After a rainy weekend, I got in my car yesterday to find a quarter inch of rain in my driver-side rear footwell (with all weather mat). It seemed that water had come in via the door as the carpet was wet in the corner between the door and the rear seats. I did my best to towel dry the footwell before it occurred to me to check my front driver's side footwell too. Lo and behold it was quite damp beneath the rubber mat. My driveway is angled towards the driver's side so I then thought the water could have entered from the front and made it's way to the back - or it entered from both places.

I did some digging online and decided to try the sunroof drain holes by pouring water in each corner with the roof completely open. It seemed to me that each corner (front and rear) drained normally. I then checked the drain plugs beneath the plenum and found the passenger side plug easily. That one was full of trash and I fished it out and emptied it. I can't for the life of me find the driver's side drain hole beneath the master cylinder though. I tried looking with a flash light but don't see it and I can't contort my hand enough to poke around in there.

I decided to try pouring water on the corner of each side of the hood and the passenger side drained immediately while the driver side seemed to be noticeably slower and drain less volume. My guess is the driver side drain hole under the plenum / hood might be blocked leading to water seeping into the driver's side of the cabin. I don't know how to clean it though. Any tips / suggestions / diagrams on this?

As for the rear footwell, I poured water the rear window, around the car door (while closed) and saw the water come out the bottom of the door. I ran my hand below the door looking for drain holes but can't find any. What could I be missing there?

Thank you to everyone for the years of knowledge on this forum. This is my first German car and I'm looking forward to enjoying it!

DanfZX14

Did you inspect the door weather stripping to see if it is installed properly or damaged?

OLI77

Not for sure because I am new to the Audi gig and have never gotten into one of the doors, but in the older BMW E46, the vapor barrier inside the door, between the area where the glass slides up and down and the door card would sometimes leak. All you had to do was to find some type of butyl tape material to redo the plastic/ rubber seals around the perimeter of the door.
Maybe a DIY to the rear door card removal would help. Here is a link to one or two.

John Simcox

Early C7 A6s have a history of water ingress through the front doors due to a misalignment of the seal around the speakers which diverts water into the car rather out through the drain holes. Audi issues a TSB for this to fox it. Sounds like your car may not have had the fix