This isn’t a topic I would want to write a second part about. Fortunately, this time it isn’t back in the trunk. In fact, I checked the trunk a few times since I wrote the first part, and the water ingress there seems to be gone. No, this time it is inside the trunk lid.

I noticed some rust spots on the inside, by accident, back when I installed the dynamic tail lights. Given that I had to remove all the trim pieces, I decided that I could install some sound deadening material too (this definitely made the lid feel more solid). Over the time, I noticed that there were a few drops on the bottom side. It wasn’t raining a lot, so I figured to monitor it over time. So when it finally rained a lot, I checked the trunk lid again, and there were a few drops of water.

A bit of water inside the trunk lid. Note the rusty spot (surface layer only).
A bit of water inside the trunk lid. Note the rusty spot (surface layer only).

Since I also replaced the rear wiper seal last time, I first checked that. But it was completely dry, with no signs of water on the inside. I also checked the rubber grommet I replaced earlier, but that felt dry too. And since it is mounted sideways in closed position, I don’t think water will enter there so easily.

I googled for some help, an the two things I found were the tail lights and the drain tube for the logo. I checked the seals of the new dynamic tail lights, but they seemed fine and not mounted improperly. Also, I cannot think of a reason how water would enter via the tail lights, as they are mounted in an enclosed space where water runs off.

The drain tube also seemed fine, but given that I still had all the trim pieces off, I decided to replace the drain tube as well. It only costed a few euros. The new part I ordered had part number 510 827 861 and was transparant instead of black. I had to cut the new tube to length, and it definitely was a tigher fit: the old tube felt hard and worn-out. I also cleaned the tube connector, as it was quite dirty.

The old tube removed.
The old tube removed.
The tube connector location with the tube removed.
The tube connector location with the tube removed.
The dirty tube connector.
The dirty tube connector.

I don’t think this will solve the problem, but at least one more thing I can rule out. I will monitor it over time, given that autumn is coming, with more and heavier rain. And maybe, I can get some help of a garden hose.

part 1 - part 2 - part 3