![Evil or Very Mad :evil:](./images/smilies/icon_evil.gif)
The problem turns out to be the sealant they put in between the roof panel and passenger side panel before they weld them together at points.
At the back, where the cover strip trim ends in that screwed on plastic piece, there is a hole for the screw.
The hole is not the problem, but the area around it must have somehow managed to make the sealant prone to cracking where the water comes down there. The right side also has a crack, but no water on the inside (yet).
![Click to view larger picture](https://preview.ibb.co/bReD7x/roof_leak_1.jpg)
So the water flows along the trim and finally meets that crack and some of it then winds up on the inside.
You'll only notice this at the bottom, where the seatbelt is fixed in that corner by removing the carpet a bit.
For a full view of the action you have to remove the plastic covers in that corner.
From there the water naturally flows downhill along the sill till it's in the front. Everything in there gets soaked wet and a bit later rusty.
![Crying or Very Sad :cry:](./images/smilies/icon_cry.gif)
The syringe was for testing if the water really gets in through that crack.. and yes it does. I put my thumb underneath the crack and let the water sip onto it and nothing into the screw hole to the right of it. The puddle is what made it to the inside.
![Click to view larger picture](https://preview.ibb.co/c2v9fH/roof_leak_2.jpg)
Now I'm looking for some flexible, low viscosity sealant that is waterproof, that wicks/creeps into those voids and then cures flexible to close them.
Self leveling seam sealer seems the way to go at the moment. 3M, Wurth, Norton or Evercoat have those for like $50 for 200 ml. Way more than I need to fix this though..
![Sad :-(](./images/smilies/icon_e_sad.gif)
Anyone any other bright ideas or experience with the seam sealer stuff?