So today I noticed a tiny damp patch on the top of my mats where my heel rests - and indeed it was pushing hard on the carpet and transferring through a bit of damp from under the carpet. Got under the carpet, a few drops here and there - nothing major. But obviously don't want to turn it into a problem so looking into the usual suspects:

1) ECU seal - took lid off ECU and unclipped ECU out of the way. Though the plastic ECU housing is sat in a few mm of standing water, I can't see any water passing the seal. Pouring a few cups of water around the outside of the ECU housing shows it draining down under the brake cylinder and out of the car. Can't feel any moisture on the foam insulation on the other side of the ECU hole, whereas when I did the pollen filter on the other side this insulation was soaking. So I don't think it is going though here.

2) bonnet release seal - while ECU was out I had a feel through the hole (small hands...) and I could touch the back side of the bonnet release grommet, as one end of the grommet under the bonnet is again under a few mm of water. Can't feel any water on the back of the grommet.

3) Driver door. I can see drips of water between coming from between the inside door trim and the door, near the front speaker, so I guess the seal has perrished. But I am a little confused (not hard). Would passing the door seal end up on top of the carpet, or would it go under the carpet? I would have thought it would end up on top of the carpet?

I had this problem with both front doors with water coming from behind the door card. Finished up having both carriers replaced - Ouch!!!!

Thanks for replying. Was the water ending up on top of your carpet first though, or underneath it?

Edited 4 June, 201214 yr by jimbof

Hi Jimbof. I have the same problem buut it's intermittent.

I've done all the same tests as you, even run a water in the plenum to make sure it runs out (it does) and can't figure it out.

However, I have figured out what makes it intermittent. Opening and closing the bonnet!!

I know, it doesn't make sense to me either. The only thing I can think of is that it's something to do with the seal that runs around the top of the wing joint and plenum front.

Right now, I don't have a problem even after all the rain last week but I'm afraid to open the bonnet in case it returns.

I hope this info will help someone detect a cure - I'm gonna have to lift the 'hood' at some point.

I've seen some people complaining about panel seams in this region too on other forums, could make sense and explain why it is drips rather than a torrent. Under the carpet I noticed a few exciting things including a piece of that join covering stuff they use which seems to have been badly applied (twisted), and also there is a pressed metal hole in the wheelarch I haven't seen before (big enough to put a finger in). However I can't get any water to leak from the front / driver wing of the car or the sunroof drains despite pouring litres on, so it looks like the door is the only confirmed ingress I have (can get several drips in a minute or so, so hours of rain would be quite significant). Still not convinced this is the route it is taking.

For the moment I've taken a bit of the VW sealing cord putty stuff left over from fixing the pollen filter housing and run it along the bottom of the door carrier panel (I can see a nice juicy bit of corrosion in the front corner near the speaker where it is letting by). We will see if this has the desire effect.

Here is a piccy of the wheelarch seam I was talking about. Does this look normal to you guys? you can see the pressed hole, and also how the sealing / sound proofing? material is applied twisted and with a gap.

Edited 7 June, 201214 yr by jimbof

Well looks like driver side door seal has sorted it. Loads of rain today and not a drop under the carpet.

Ordered a whole reel of that sealant strip to do all the doors.