Botang's hole IMHO
Same location on LHD and RHD cars

That's what I was worried about, if that beam goes accross the whole car the leak could be somewhere from the middle then trickle down all the way to one side or the other.

I'll have a look under the ECU box, its on the right side for me.

If that's so, then it definitely doesn't exist on LHD cars, because that area is occupied by the pedal box cut-out, and the area between the pedal box and aircon heat exchanger box in the middle is clearly visible and has no other holes.

I am going to have another look tonight with a borescope camera, first by going along the inside of the duct to see if that reveals anything. My suspicion currently is that its something to do with the huge middle box containing the aircon flaps and heat exchanger, that goes through a cut out in the body doesn't it? Plus it has the scuttle drains below it. Sounds like a potential problem area.

Sergey, apologies, I think you are right!
It was raining all day today so when I got home there was a bit of water in the footwell and I could see it trickling down in various places.
As I was trying to plug the square opening in the internal beam with kitchen paper as best as I could I noticed a hole in the roof of that beam which I hadn't seen before. From the inside the hole looked blocked but putting my finger on it water was definitely coming down it.
From the engine bay no hole could be seen. So I grabbed a wooden skewer and stuck it through the hole, it went through easily. Then the hole location was obvious from the engine bay. It is just below the big rubber grommet for wires that go into the cabin.

Stupid, stupid Audi engineers, I curse you, why would you stick paper over a un-used hole then carefully paint it like the rest of the body so its impossible to see from the outside?
Is this some big joke you played on us?
The paint, supported by paper only, naturally develops an invisible crack over time letting water soak through the paper resulting in a perfect stealth leak.
Was it so hard to put a rubber plug into it just like the other unused hole just inches away? Or even weld it up? Grrrrr!

Well I blocked it temporarily from both sides with bathroom silicone sealant, tomorrow I will bolt it up with silicone sealant sandwiched between the bolt and nut.

Hopefully this is the only remaining hole, I will know tomorrow as its going to carry on raining all night.

Pictures to come.

http://forum.a8parts.co.uk/attachmen...1&d=1499809688

Post a picture how it looks like from the top.
It does (!) exist on LHD cars.

Pics for LHD cars:

http://s019.radikal.ru/i601/1307/d6/535ca1080680.jpg

http://s019.radikal.ru/i644/1307/6d/04034aef80dd.jpg

http://s017.radikal.ru/i438/1307/31/d789bf4480a1.jpg

http://s019.radikal.ru/i620/1307/bf/0ee596bc5ae8.jpg

As I said in post #2 of this thread:

That should be easy to plug with a rubber well nut of a suitable size.

That's it! Exactly the same location. I will post a pic before I plug it. I never new Botang's hole was there, I thought it was further down closer to the middle.
What a nightmare!
The location is pure genius, it is positioned to trickle water down several wiring looms, drip onto relays and onto a group of earthing points on the chassis!

Thanks I will give those bolts a try. I was going to just use an aluminium bolt and washer filled with silicone, but those look better.

Thanks for your help +++

P.S. even though it rained all night, this morning no more water in the footwell, so hopefully Botang's hole is the only leakage point on mine.

I used a couple of those well nuts to fix my reversing camera, they work really well. Make sure you get brass (or stainless steel).
Easy to fit, access for fixing needed from one side only, good seal, simple to remove/replace, no problems with corrosion from metal contact. +++
(And if actually used to fix something are surprisingly strong)

Finally fixed it. I couldn't get any of those well nuts in time so I used a M6 aluminium bolt and one of those Audi anodized nuts filled in with silicone rtv sealant and a nylon washer and tightened. It was a right pain to fit the nut and tighten from the inside but surprisingly can be done by one person.
Then filled the whole area where the original fabric patch was with more silicone.

http://forum.a8parts.co.uk/attachmen...1&d=1500069385

Sorry this pic is upside down :)

http://forum.a8parts.co.uk/attachmen...1&d=1500069385


http://forum.a8parts.co.uk/attachmen...1&d=1500069385

Glad you sorted it Goran