Water is leaking into the boot of my A3 Cabriolet and I have no idea where from - PLEASE HELP

[costing]

Hi I’m at my wits end every time it rains it leaks all in the bottom left hand side of boot but can’t understand from above why it’s coming in? I’ve taken soft top roof motor out and can see it leak in everywhere, but the set up is no different to the other side of car , has anyone ever fixed this persistent problem ? Cheers

[Westo]

In reply to all who read this post I have still not resolved this issue so recently I have put a considerable bit of effort into trying to solve this : -
After my initial dealings with the Audi dealership and the possible open cheque approach I decided to once again try to tackle this issue the following are my experiences to date 2024.

1. I striped the interior of the car from the boot to all the side trims, back seat and roll bars to give me a better visual and easier access, took me two days.
2. This did not improve the visual view of the drainage system of the hood or being able to see where the water was exactly coming from.
3. There are two drainage cups either side of the back rear quoter which sits on the self behind the rear seats, that take the water from the hood drainage channels which then drains through the upper wheel arch, these some times block and cause the water to overflow into the car, I removed the cover from the nearside one and flushed it with water through that one and it drained away easily.
4. My next task was to clean and proof the hood, they recommend using the spray bottles in the pack for both the cleaning and proofing I used a paint brush to apply them instead much cleaner and easier.
5. Next I opened the hood to half way there are drainage channels on the folding arms of the hood to be exact 3 separate channels each side giving you 12 joints (as possible leaking point) I used good quality automotive silicon to lubricate each mating surface (Silicon water proof) the mating ends of these channels looked less than you would expect a water tight seal to be. Removed excess silicone (this a non-setting product) they instantly looked much cleaner and hopefully a water seal.
6. I next I opened and closed the hood several time and inspected the channel joint’s they looked fine.
7. Closed the hood and used the house pipe over the hood and paid particular attention to the rear near side quarter, low and behold no water in thought that I had fixed the issue.
8. Heavy rain due that evening so thought leave until the next morning.
9. Next day water in the same place so no fix, what I did notice was water over the vent flap, the flap is in the near side rear quarter it also looked as if was not fixed touched it and it fell into the bumper managed to retrieve it, so decided to seal the opening with gaffer tap and leave over night as rain was expected.
10. Next morning water in again so back to square one, some posts say that there is a drain tube in the right-hand side of the rear bumper, which gets blocked that might be on the A3 Car but there is not one on the Cabriolet.
11. I have all the pictures if anyone wants to see them.
12. Not sure what my next move will be I just do not know what to do next. Any input would be helpful.

[mazerati]

Hi,

Sorry I can't help specifically with your car.

I managed to trace a similar leak once by visiting a plumbers merchant or screw-fix and buying some fluorescent dye
what they use to trace leaks in drainage pipes. I mixed some in a watering can with a sprinkler ( don't over do the dye).
Start from as near to where the water is entering the boot . If it is entering you should be able to trace it much easier with the water colored.
If it is not getting in move gradually further away.
And of course there is the old method of shutting someone in the boot with a torch.

Good luck.

[Westo]

Hi
Using a 1L jug I slowly poured at least 4L at a time in several areas around around the rear quarter near side panel, form center of rear window to the edge of the front door and no ingress of water, poured water over the rear light about 4L then 4L to the drainage channel between the rear quarter and boot that's between the light and boot again no water.

The flap valve I have just reinstalled but i put non setting water proof silicon around frame seal, this without taking the bumper off, by putting a stiff wire around the center of plastic between the flaps to stop it dropping through you have to put the bottom end in first as there's some thing at the right hand side that stops it going in, it was unbelievably easy to do I used a long right angled Rolfson probe to pull the four inbuilt clips on the frame of the vent into position as it fell out in the first place I hope that this might be the issue as it must have been lose in the first place for it to fall out.

If not have some further thoughts what I might do next such, as to isolate specific areas on the near side with a waterproof cover separating the bodywork from the hood and vice versa

[Westo]

Well after weeks of looking to solve this issue without success and considering what I have done to try and find the issue, also the fact that i have poured in-access of 10 liters directly into the drainage channel on the rear near side with no leek, and only having water ingress when it's raining is baffling to to say the least, and having reproofed the hood.

I had a eureka moment :-

Given that only the rain situation produced a leek to the rear near side quarter and that water seemed to be coming down from the rear panel and not the wheel arch, I decided to partly lower the hood to expose the joint of the hood fabric to body on the rear quarter using a fixable plastic tool covered with a cloth i gently clean the the mating surfaces and surprised how much muck came out, I now suspected the stress and contamination at this point might have had an issue to the integrity of the water proof propitiates of the hood at this point.

Realizing that i had not proofed this section of the hood as it was cleaned and proofed in the closed position, I duly cleaned and proofed this area we have had rain for two days and extremely heavy last night and no water leek !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!.

I am hoping that the issue is now resolved at long last, this after stripping out the rear seats role bars and all internal rear side trims of the car which I thought would give me better visual access which it did not.

Will keep you posted.

[Danny75]

Hi,
Do you have any pictures of the area you cleaned please ?

[Danny75]

So on investigation of my own leak, I sprayed the roof with water and found the top was leaking through the plastic piece that holds parcel shelf up.
The shelf has come away from the window on the inside and when I felt the back of the shelf it was soaked . So I still don’t know where the water is coming in . I think it’s either the bottom of the window, or the seal where the hood touches the boot lid ?