I have water getting into my S6 avant 2017. The interior is light grey, the drivers seatbelt gets wet and has discoloured. I’m on South Coast and we have had lots of heat waves this summer. Last winter the rear drivers side footwell got a wet carpet. I’m not sure if it’s passenger side as well, as it’s not used very often. Both drivers and passengers door cards, - light grey suede - had white water marks on them.  I don’t have a sun roof of any type but have roof rails.  Any ideas please ?  Thanks 

The topic of wet footwells comes up from time to time so it would be worth looking through forum history for ideas.

A wet seatbelt is something I have not heard of until now. There must be a leak fairly high on the body for that to happen. Are the door and windows seals intact? Are the doors and windows in fact fully closed?

Yes doors and windows fully closed. It even happens when I’m inside the car and it’s being washed. All seals seem intact and no gaps or anything.  My thoughts are the same as the seat belt is wet it must be high up and dripping down on the belt all reeled up, inside the middle pillar. 

Possible roof rail ‘seal’ issue?

ok thank you for your suggestion and reply 

Never heard of a roof rail issue as cause of water ingress on A6 or even A4 Avant, but never say never.

If no panoramic, then that kind of rules the obvious culprit which I’ve dealt with before, however if the car has been subjected to heat, and I know there’s been some daft temperatures down south, then anything is possible.

The fix won’t be straight forward, but leaving it, then you risk mould, damage to electrics, airbags and interior trim, etc.

Wet seatbelts, is that at the mechanism lower down or higher up? The reason I’m asking is if there is wet staining higher up, you have no choice, you’ll need to drop the headlining.

Prior to doing any of this, rule out blocked plenum drains. They live behind the bulkhead behind the engine under the wiper mechanism. Also check the rear spare wheel area where the space saver and amp lives, including both rear arch compartments.

If it is leaking above, then you’d likely see condensation in the car. To drop headlining, you need to detach battery leads in boot, leave 30 mins. Most tools are anti-marr plastic trim tools, Torx screwdrivers, plus special tool for interior grab handles. You need to work clean. Light grey interior trim marks very easily with dirty hands, so clean tools, nitrile gloves, etc.

I can post more details on the headlining drop but confirm some details first. The trouble is it’s labour intensive and most garages aren’t set up for this type of work, it’s really more a body shop thing.

One more fairly remote possibility occurs to me. Has the car been in a crash that needed the body to be straightened in a jig? If that is not done properly it can leave the body slightly twisted such that the doors appear to close fully but the rubber seals are not crushed enough to be water proof.

Hi @cliffcoggin  thanks for your reply.  The car hasn’t been in an accident or been in a jig thankfully.

@spartacus 68

Thanks for such a detailed reply I appreciate it.  I have taken the spare wheel out and it’s all dry in there and the boot area as are both rear wheel arches. The drivers seat belt is badly discoloured and gets wet, where it must be sitting in the reel when the belt is not done up.  I looked under the bonnet and slightly removed the cover near the windscreen. It’s pretty dirty in there where leaves have collected over the years and some turned to soil - this is either side. I really don’t know what I’m looking for with the drain you mentioned and whether it can be seen while the car is on the ground - or does it need jacking up?  I felt the carpets in the front footwells and they appear to be dry, I hoovered them as well and it didn’t bring any water to the surface. The bonnet catch seems dry as well. 
The car was damp last winter as well and the summer last year wasn’t as mad as this year. During the day the car is parked in the shade as my driveway is north facing. 
I appreciate what you have said about the headlining. Although it is a light grey interior so seats, door cards, seat belts are light grey, it is a black edition so has a dark headlining and carpets - hopefully this will help when it’s taken apart!! I’ve had a look and have never taken a car interior apart before but also can’t afford paying Audi hours and hours of money, for them searching for the leak. Any other help would be appreciated, thank you 

 

Front bulkhead plenum drains block easily. They are rubber grommets. Get a torch and take a look. You will need to remove the plastic cowl next to windscreen.

On the headlining, is there actual staining?

@spartacus 68  No staining on head lining but it’s very dark grey.  There is staining on the light grey door cards. 

Hi Caroline,

 

Have you checked the bonding around the top of the windscreen? 

Before going to the hassle of dropping the headlining, and trust me it's a lot of work, then I think you need to rule out water ingress at the doors. As mentioned already - it could be the actual seal on the door rubbers is compromised. There should also be drains on the doors - check they are clear too. 

If the car went to Audi they would water-test it before they do any work, which is basically a technician sitting in the car while a colleague uses hose. This seems to make sense - as water finds the easiest route in. You can use paper towels, basically anything to show, especially along the interior plastic door trim.

The actual roof lining is just a card template with material bonded to it, The A frame and C pillars are plastic, so seeing staining here is difficult. Unless you have physical evidence the water is coming from above - I would look elsewhere.

@Kev-P thanks for your reply.  No I haven’t do I need the head lining off to do that? Thanks 

 

@spartacus 68 I had a very long look under the bonnet couple of days ago. I removed the cover near the windscreen- removed as many of the leaves and soil I could reach. Spent a long time trying to find the drains under there with a torch but couldn’t. 
I went round all the doors and removed the bottom rubber seal - this is intact, the drain holes were clear and no water came out or heard. 
I took the spare wheel out of the boot - it’s all dry in there, no sign of water or condensation.  The same with both rear wheel arches - completely dry. 
I watched a video or 2 and they said about removing the cover between the bases of the windscreen to access the area below this after removing the windscreen wipers.  As I struggled so much with the engine cover, getting it back into place, I didn’t want to remove this lower windscreen cover - for fear of not being able to put it back together! 
so I have removed a couple of water ingress points - rear of the car but now stuck moving forward as basically too weak!!  Thanks for your help 

Post up some pictures. Absolutely no idea if this is the culprit, but you never know. In the meantime, get a dehumidifier in the car.

Anywhere where there's staining, you can use warm water and a small splash of carpet cleaner solution. Don't soak.