[RS61]

2021 F90 M5 LCI. Haven't driven the car for a few months. Took it out today, while loading up the boot saw that there was loads of mould everywhere.

Tried to work out what was going on, and discovered that the right side plastic bin in the boot was full of water. Not a little bit, like literally full of water.

Nothing else was wet (and it wasn't that one of the water bottles leaked out) so somehow a lot of rain water dripped into it from the outside. Anyone else experienced this, and knows what needs replacing?

[Alberta]

May be you can find some info in this thread : https://f90.bimmerpost.com/forums/sh....php?t=2078311

[pbonsalb]

Tail light seal, sunroof drain if sunroof, trunk opening gasket are all possibilities.

[RS61]

Thank you. Looks like the gasket will need replacing. There's no obvious damage to it, which is why I was uncertain, but when I pour a jug of water on the car and open the trunk, the gasket is clearly wet in a way it shouldn't be.

[pbonsalb]

Maybe the rubber fails and compresses a bit. Does it look mushroomed or squashed at all? Curious of height from car body to top of seal on old versus new.

[RS61]

I spent some time pouring water on the car and watching which bit got wet, and it's this part here in the top image.

The water comes over the top of the seal, then it drips down into the small gap where the hinge of the trunk comes out, and then leaks through that into the plastic bin.

That's what was happening to you, right? Mine was also very gunky, but I've cleaned it all up and it's still happening.