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.