Rain getting in!

[richtbiscuits]

It's rained hard here today and turned the passenger footwell in my 412 into a mini lake. There was damp coming down through the carpet from the fresh air blower although I couldn't see any drips from the blower unit there were droplets of water suggesting a trickle (torrent!) from that area under the carpet. It all pooled in the nearside front footwell. I've soaked up what I can but I'm worried about the state of my floor. It's rusty and needs treating. Anyone got any bright ideas how to get the rubberised sound proofing/strengthening mats off the floor? They're pretty well attached and need to come up to assess the floor but I don't want to ruin them. Anyone had leaks from the fresh air box before and found the route causes? I'm thinking either leaking seals or a blocked drain. Thanks in advance for any and all suggestions.

[Rob 400e]

The only thing I can think of is a good heat gun and scraper, take your time trouble is the mat will be brittle. You can buy rubber type matting for the roof of cars the quality is not on a par with VW factory but it is an alternative.

[Rob 400e]

Just to add to my post if you go ahead with the heat gun don't get the mat to hit it defeats the object. Concentrate on one edge, you want to start melting the glue, then use your scraper to gently slide under the mat keep the heat gun moving.

[937carrera]

In my experience, age has taken it's toll and the sound proofing will be brittle and break as you attempt removal. or even after you move it around after removal

The only technique I could suggest in addition is to heat the floor from the underside

[Dave Summers]

My 411 4-door had a howling gale coming through the air blower box due to rust. Sounds like yours has enough rust to let some water through. If it hasn't then the leak must be somewhere else like the windscreen seal, but the air blower box sounds the most likely. If you remove the carpet under it you should be able to check it fairly easily. The drain can get blocked with leaves but it's pretty big so not likely on a car that's being used. It's easy to access with the blower fan removed though.

[richtbiscuits]

I removed the carpet the day it happened to try to trace the leak. The metalwork is remarkably sound (I was pleasantly surprised!) but it was certainly where it was getting in. I inspected under the dash but could find no sign of water, droplets, dampness or otherwise. It only leaks under heavy rain, it's fine when it's light rain or a shower which makes me suspect a blocked drain (the car was off the road for four years prior to me acquiring it and it stays garages when not in use). When I get a fine day I'll pull the heater and have a look at the drain. Until then the scuttle vents are taped over! Thanks for all the advice.

[richtbiscuits]

Well, I taped up the fresh air grille on the scuttle panel and having had some heavy rain it is still dry inside so at least I know where it is getting in. Just need to determine why now!

[JSR-69]

The box doesn't need to be rusty to let the rain through. If the drain hole is blocked then rain water will accumulate and overflow through the fan. You need to take the fan off (a couple of screws once you've removed the air hoses) and poke the debris out of the drain hole.

Judi

[oldtimer]

I`m having the same problem. Vent holes were taped up but the damage has already been done. Both bottom and top corners on mine have rusted through along with the adjoining bulkhead. Good luck .

[richtbiscuits]

Thank JSR-69. I've not had the chance to investigate the ins and outs of getting to the drain holes yet but if it's not to exhaustive I might have a fighting chance of a couple of hours at the weekend. I'm pretty sure that's what it'll be as the water in is proportional to the rain coming down! Where does the drain exit the car? Somewhere on the underside I assume but if you, or anyone, could point it out I could slide under and take a look. Thanks.

[Dave Summers]

The drain leads to a hollow in the sloping panel that the rear edge of the petrol tank sits on, and then to the bulkhead behind the petrol tank. So you should be able to see water coming down the bulkhead, on the centre line of the car.
If metalwork is needed it's totally inaccessible without the major job of removing the front suspension and petrol tank, but if it's just blocked by leaves or other debris, taking out the fan blower and then poking the drain with a big screwdriver, preferably followed by a blast of compressed air, should be enough to clear it.

[richtbiscuits]

Thanks Dave, exactly the info I was after. If I get out of work early enough I'll try taking out the fan and clearing it.

[richtbiscuits]

I finally got round to taking out the fan to investigate the leak. What a fiddly job. The access is awful, sore back after lying across the sill to get under the dash. Finally got everything out, debris and all. The drain wasn't blocked. Someone has put sealant on the seam before so it's an historical leak. The rust isn't too bad. I've treated the inside of the air box with rust cure and I'm going to paint it with several coats to seal it from the inside. Also a good excuse to clean up all the parts and replace the brittle foam on the air vent flaps. It's all good fun!

[broady_6]

[Dave Summers]

Glad you're getting there. The dashes have been out of both my cars for a long time so I couldn't remember how you would get in with the dash in place. Sounds like you've got a bit of porosity but hopefully it's little enough for some good sealing will do the job. But if the leak is only at the seam it could just be old, brittle sealant.
I've just had a look at it on my 411 (awaiting restoration) and the sealant is good, with the factory paint intact, for most of the way round, but it's rusted through below the drain (allowing water inside the car, although in my case there's enough "ventilation" to let it out again), so I suggest you check that area carefully with a wire brush or scrubbing disc.
Taking the dash out isn't too difficult if you need better access, as long as you label the wires.

[richtbiscuits]

The air box saga continues. I've put the first coat of paint on today. It's not easy to do - scratched wrist trying to get into the space and can't see anything. All done by feel and camera on the phone to view my work. First coat is white and has gone on okay with plenty of paint in the bottom of the box. I can see the paint forming a little droplet where its come through the metalwork so it should be sealed now. It looks to me like the air box has two sheet metal skins and the outer skin is worse than the inner skin, presumably because water gets trapped between the two. The rust is worse than I thought on the n/s corner although still only 2p piece sized. I'll let the paint go off then paint again, this time in black so I can see what I've done then repeat white, black and white again - might as well while I have 'access' to it. Crafted some foam pieces for the vent flaps too which I'm quite pleased with. Still, its always two steps forward and one back and today's is a screw through the o/s rear tyre!