Pluvial Incontinence

[audiacious]

My car keeps pi$$ing itself.
It manifests itself in the passenger rear footwell.
I have been vacuuming out rain water for the past couple of months each time there is heavy rain. Usually ~1L after a heavy downpour.
I previously removed the windscreen "scuttle"? and repositioned the foam thinking this was the culprit, no joy.

Yesterday I eventually got round to taking the cabin filter housing off, removing the detritus that had built up at the wing side of it, thinking that was the culprit. It seems it is not, it's rained quite heavily today and now the carpet is splashy again....

It's not the washer fluid; there is no foam or smell when I vacuum it out.
It's unlikely to be the AC condensate; the water accumulates whilst the car is unused, unless there is some lag.

One thing I noticed for the first time on Friday after driving through heavy rain; the carpet was wet near the blower outlet but not back towards the seat. Could the water be entering the AC system somewhere else? I have heard it gurgling before upon startup.

I've heard mention of doors leaking but I can't see how that's possible since there is a lip and the water would have to travel up hill.

I've heard of people using food dye to pinpoint the ingress but I'm avoiding that for the time being, since; I don't fancy colouring the inside of my car, plus I don't have any.

Any advice would be appreciated, I am wary of sending it in to a garage because I have heard they can take dozens of hours troubleshooting and still not get to the bottom of it.

[bam_bam]

What did your forum search yield, out of interest?

[audiacious]

Most posts point to the cabin filter housing which I've pretty much discounted.
Next up is the washer convoluted tubing bursting off the junction under frozen conditions.
lastly, it's the AC condensate, I doubt it's that.
There were some mentions of plenum bungs on various forums but I've already tried pouring water into that and it drains nicely.
Oh and some mentions of door cards but as I mentioned I cant see how that's possible, plus the carpet is not wet up near the door.
...Hence the post.

[bam_bam]

Do you have an OEM hole in the roof, could be the sunroof drain.

[audiacious]

No sunroof.
I notice that after heavy rain the boot hinge recesses (Avant) fill up with water but I doubt it could get in there.
Ever heard of it getting in through the roof antennae? I suppose I wouldn't see such volume through there.
I suppose I should invest in a car cover in the short term - or clear out my garage, before the convenience module begins to inconvenience me.

[deanosabby]

Have you taken the battery out and cleaned out the rubber drain bung?
I had a wet carpet on the passenger side and cleaned out dead leaves and all sorts of other stuff and since then it has been dry.
HTH,
Ta,
Deano.

[Shoppinit]

The battery is in the boot in the RS6.

Could be a poor seal on one of the rear lights. Pull the trim out of the boot and crawl into the boot while someone hoses the car down. The water makes it way down into the foot well, especially when you brake.

Open the battery compartment to see if any water has accumulated in it?

If it's try then I would take off the rear door card to check the weather membrane on it. Not prone to leaking on RS6's, but it's not impossible. Again, do the hose test on it.

[audiacious]

Ah, I hadn't thought that the lights could be a source.
I'll give it a try.
Thanks.

[deanosabby]

The battery is in the boot in the RS6.

Could be a poor seal on one of the rear lights. Pull the trim out of the boot and crawl into the boot while someone hoses the car down. The water makes it way down into the foot well, especially when you brake.

Open the battery compartment to see if any water has accumulated in it?

If it's try then I would take off the rear door card to check the weather membrane on it. Not prone to leaking on RS6's, but it's not impossible. Again, do the hose test on it.

Learn something new everyday

Does the RS6 still have the same bulkhead arrangement as the rest of the C5 car's?

[bam_bam]

*cars

[rob8457]

Just like a woman always weeping

[deanosabby]

*cars

I did write cars but the computer auto corrected it.

[spurtle]

Have you taken the battery out and cleaned out the rubber drain bung?
I had a wet carpet on the passenger side and cleaned out dead leaves and all sorts of other stuff and since then it has been dry.
HTH,
Ta,
Deano.

As has been pointed out, the battery is in the boot but I think a blocked bung in the plenum chamber (under the coolant reservoir) is the most likely cuprit given the level of water ingress. I've had no less than four Audis with *exactly* this problem (though not the RS6; maybe because I keep it clean and try to avoid parking under trees). Worth investigating even if the plenum chamber seems to drain freely - remember a lot of water can get in there during heavy rain and it may accumulate faster than it can drain.

[imacool]

Have you taken the battery out and cleaned out the rubber drain bung?
I had a wet carpet on the passenger side and cleaned out dead leaves and all sorts of other stuff and since then it has been dry.
HTH,
Ta,
Deano.

As has been pointed out, the battery is in the boot but I think a blocked bung in the plenum chamber (under the coolant reservoir) is the most likely cuprit given the level of water ingress. I've had no less than four Audis with *exactly* this problem (though not the RS6; maybe because I keep it clean and try to avoid parking under trees). Worth investigating even if the plenum chamber seems to drain freely - remember a lot of water can get in there during heavy rain and it may accumulate faster than it can drain.

99% it is the plenum chamber drains. If they are blocked, you get water ingress through the air vent intake and it will end up in the rear passenger foot well. Common problems not only with Audis but with all VAG cars. I have friend with Passat, he had exactly the same problem after heavy rain.
The best is to lift the car, drain pipe ends in the RS6 C5 are located behind the front wheels and then you can check if they are draining water if you pour some over the front windscreen.