Water mystery in footwell
 

I discovered a few weeks ago that my drivers side carpet is wet, not from above but from underneath.
I checked the orange drains either side of the centre console first. They were in good condition, dry and not blocked.
With dread I started searching for Botang's hole. However as the car is LHD I either don't have it, or if I do its on the passanger side so not relevant.

So I started with an experiment. I removed the carpet and loosened some of the sound deadening but couldn't see behind it properly as its huge and the top of it is pined to the bdy work somewhere up high behind the dash. I poured water down the windscreen then jumped into the footwell with a torch to see if any water came in. And sure enough it did but not where I expected, It dripped down from somewhere above to the left near the corner of the dasboard. The only possible entry points I could see from the Engine bay are a big rubber grommet with some wiring loom going into the cabin, a small orange rubber plug next to it, and the pedal box itself. If the butyl cord seal had failed that would be a real pain to re-seal the whole edge of the pedal box. Audi design of the hole in the firewall for the pedal box is not good, there is a flange around the hole allowing water to collect and sit above the bottom edge of the pedal box and body seal. I suspected this was the most likely entry point.
I got some black silicone sealant from Halfords (only 40g - doh!) and proceeded to seal the two grommets and the edge of the pedal box from the outside as best as I could. Cleaning and sealing the two grommets was easy, reaching in and sealing the edge of the pedal box, especially the bottom edge, was almost impossible. I did it somehow in the end with the help of a short length of silicone tubing, although I cant claim the seal is good because I could not reach the edge to clean it first. The best I could hope to do was fill in the channel created by the flange so at least there could be no standing water it would have to slide off.

What about your scuttle, is that dry?

As for Botang's hole I would imagine it's in the same place (your drivers side) but maybe actually used for something, unless it's an artefact of the manufacturing process.

Where is the scuttle? Is it above the two orange drain plugs either side of the centre console?

Under the bonnet, where water drains into from the windscreen. Access is largely blocked by the air intake to the HVAC unit.
It has a pair of big drains down either side of the transmission.
Mine gets blocked very easily from debris (leaves, seeds etc.) and overflows into the cabin.
The red circles on the attached pictures show plausible blockage points, mine is mostly the upper ones at the base of the tray (line drawing).

Here are pictures of this attempt to block the water ingress.

First picture is evidence of water dripping in.

http://forum.a8parts.co.uk/attachmen...1&d=1499721129

http://forum.a8parts.co.uk/attachmen...1&d=1499721129

http://forum.a8parts.co.uk/attachmen...1&d=1499721129

http://forum.a8parts.co.uk/attachmen...1&d=1499721129

Thanks! I'll check that too but I did not see any standing water down there even when I pour a whole bucket down the windscreen. Also seems too low down to be related to my problem.

If you pour a bucket of water on the windscreen it should come out immediately under the car, both sides behind the engine.

I was happy for a week :rolleyes: Kept checking the carpet, it was dry, even after a little rain, but it was not a proper test. Then I washed the car yesterday, in the sun. And afterwards the carpet was wet, with warm water!
So today in despair and frustration I started digging in to the footwell dismantling any easily accessible trims to see exactly where its coming in. As it happens, from a most unexpected place!
I dug into enough sound deadening to be able to see the metal of the firewall and the mating joint of the pedal box. Then I poured a bucket down the windscreen. And sure enough it came in, to the extreme far left, from up above in the corner. Up there somewhere there is not just a single sheet of metal of the aluminium body, but a double-walled section a bit like a gently arched horizontal duct. And in the left corner before this double walked section has a square cut-out at the bottom. Water was coming in, like an Alien ;) inside this duct and dropping in from above!

With the sound deadening pushed out of the way I could also see the other side of the grommets in the corner, there were stains just below the big grommet for the wiring loom, water had got in via that in the past but not any more. Probably from when the wheel arch drain was blocked, I often had standing water there, so watch out for that one, worth sealing I think.

But unfortunately for me I am still none the wiser where the entry point is for my water ingress. I also suspected the lower left coolant hose going to the heat exchanger. It has a white oval seal and the lower seal is looking worse for wear, I thought maybe this seal goes through this double-wall section and may be letting water in, but I found it from the inside and it is dry with no stains. Then I sprayed water directly at just the lower seal with a hose but nothing came in.

Here is the offending 'duct'

Who is the most knowledgeable D2 genius who can solve this mystery?

http://forum.a8parts.co.uk/attachmen...1&d=1499722540

Zoomed out a bit

http://forum.a8parts.co.uk/attachmen...1&d=1499722764

http://forum.a8parts.co.uk/attachmen...1&d=1499723015

That "duct" looks like the main beam that I have seen that goes right across the car inside the dash structure.

Could Botang's hole be the leak?

Could well be Bontang's, Worth a dig around for reasurance.

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

After lots of heavy rain I've been seeing a wet carpet in the passenger footwell and also a trickle of water running down the carpet over the wheel arch. I'm pretty sure it's Botang's hole. I like the idea of a rubber well nut for simplicity, does anyone know if an M6 would be big enough?

I forgot to measure the size of the hole. Its definitely bigger than 6mm diameter, I put in an Aluminium M6 bolt and M6 nut and there was still room, its probably M8 size.

Thanks Goran. As they're quite cheap I'll probably buy a few different sizes and see. If the hole is about 10mm diameter I may need to go down to an M4 due to the thickness of the rubber on the nut.

I can confirm my water ingress was almost definitely that hole, the car has been through at least 7 days of heavy rain now and the carpet is nice and dry.

I just did this on the FE I have in at the moment and I used one of the big plastic rivets which are used on the arch liners, well covered in seam sealer.

I finally managed to get around to doing this. It was getting worse over the last few months and the wood cover over the relays is looking and feeling quite wet so may need to replace it if it doesn't dry out well enough.

Thanks to all the help from people on here I was able to locate the offending hole with only a little difficulty! I used an M8 rubber well nut and it fitted just right, slightly larger might fit too.

Attachment 17959

I then used a long allen key and could reach through to tighten it without needing to remove anything.

Attachment 17960

Two questions:
1. How did you get that first picture?
2. How did you find the hole and feed the well nut in?

That was fairly easy, I just slid my phone in on top of the ECU box, it took a couple of attempts to get it right. I just had to be careful not to push it in too far! So the first picture is looking down from above.

This wasn't too easy but using the photos in this thread http://forum.a8parts.co.uk/showthread.php?t=7645&page=2 I was able to work out the location from the two grommets and a seam in the body. A little light scraping with a long screwdriver soon found a hole. All I removed to gain access was the ECU box lid and undid the nut on the windscreen trim so I could lift it out of the way.

To get the well nut in was a little tricky as I didn't want to drop it but using some tissue paper to hold it onto the end of an allen key and some long nose pliers (I didn't have a long enough allen and had to buy longer ones to finish) I was able to drop it in place and used a long screwdriver to help push it in and off the allen key. It took patience and some care to work out the easiest way around the pipes without losing the nut. I also positioned my phone to shine the torch light so I could see better.

I didn't scrape a single knuckle either! Time will tell if it stops the water ingress or if the drains are also blocked, but it looked fairly clear of water in there.

You must have done it wrong if you didn't even scrape a knuckle. +++ If a job is worth doing right, it's worth bleeding for. :ROFL:

Excellent, those little details are what we need. +++

If I tackle it and find a better way I'll explain it here.

Well nuts are a handy device, especially with the electrolytic corrosion issues we have to beware of. I used them to secure my reversing camera.

I did wonder, I usually drop something somewhere I can't reach or manage to draw blood but not this time!

The well nut made it much easier I'm sure and there's no risk of corrosion as you say, I used a nylon washer supplied with the nut just to be sure. I think it would be fair to say the hole is almost directly below the bend of the A/C pipes, the orange grommet was my main guide though.