From what I could make out the near side rear (uk near side) kinked drain hose was causing water (and debris) to leak from the drain hose fitting near the pano roof and then down through the headliner and rear quarter panel into the area of the boot near the rear light fitting (similar to yours whereby there's a water/tide mark and debris stains in the boot itself).Yes! Your pictures are what led me here. I understand from your post that the drain hose was kinked. But where was your water intrusion coming from? Did that kink nick the tubing or was the source further down from that point, further up...?
This is the SOLUTION, I was so frustrated, until I saw this. It took me like 2-3 hours to fix the 4 drain pipes. "The ones in the back are accessible from the trunk sides, next to the liftgate there is the blue whose".I FINALLY got this fixed on my 09 Tiguan. I thought it was the spout leaking at the joint between the sunroof drain and the tube, so I re-glued that a couple of years ago with marine adhesive. In a recent storm we saw it still leaking .
I finally decided to figure it out once and for all. I bought a long bendy pipe cleaner on Amazon. Threaded it into the tube, and...got it stuck. FML. After really yanking on it, I got it and a little dirt out of the tube. But went to blow into the tube to clear out the dust, and...nothing. I couldn't blow through it. I had never thought to check to see if it was actually a BLOCKAGE causing the leak and not a little hole or misalignment. The gears started turning and I realized I could still be experiencing leaks in the sunroof as the tube fills up with water, then the roof rack channels fill up with water, and the water spills OVER the top of the roof rack assembly into the car ceiling. UGH.
So I have a blocked tube, and it's already watertight since I fixed it. Onto the work I wish I had thought to do years ago.
I followed the drain line down the A pillar, behind the dash, and pulled out the dash panel to reveal the end of the drain. Follow along in pictures.
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You can see the tube goes into a "collector" or drain end that directs it through the firewall (and eventually behind the wheel well liner).
I yanked out the collector and saw this:
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It felt heavy, and I found out that was because it was full of what I can only describe as a clod of dirt.
That's likely due to the fact that the drain end has a tiny little "x" shaped opening that allows it to get COMPLETELY clogged. Seriously?!
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I emptied it out and then cut the end of the collector off to allow larger particles to get through (Why VW decided that only water should be able to exit the drain pipe is absolutely beyond me, but I would imagine that a large portion of the people experiencing leak problems with their sunroofs are actually seeing this issue). I put it back into the hole, threaded the line into it, and made sure there were no kinks.
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I did the same thing on the driver's side. I poured a couple of gallons of water through the system with the roof open (carefully to avoid it going in the drivers seat) and closed. Works like a charm. The nice thing is if this is happening on your car, taking out that trim panel is a LOT easier than getting to the roof drain behind the ceiling panel - maybe even a better starting point. Shame it took 4 years to figure it out. And shame VW decided that this was a sane design decision . I'm thinking about moving to the Pacific NW just to get some more mileage out of this fix.