Anyone know how to stop rain water from leaking into the tear compartments? I noticed anout half an inch in the tray back there after a bad storm. The other side has a musky smell like it has been wet as well.

 

I'm guessing you mean where the battery and spare tire live? That water usually comes from clogged sunroof drains at the rear. There are little plugs on the end of the drain hoses meant to keep critters from crawling up into the pipes. Those damn things always get plugged, and cause water t0 leak into the car. I yanked them off and no problems since. I also had a leak at the tail light gasket. A replacement part took care of that.

Jose

 

That is what I meant, It was supposed to say near the 1st AID kit, fat fingers bad eyes and small phone keyboards cause spelling issues.
I removed the Udders that were clogged with gunk. I had the same issue with clogged drain hoses on my 98 Corvette.

I dried the area out as well as I could then put a moisture trap thing that was suggested for my Corvette. They sell them at the Dollar Tree.. They are about a quart size plastic container with some type moisture trapping beads in the bottom. I was able to get one snugly fit under the storage trays on both sides and another modified one under my spare tire. With all the electrical things under there i figured any thing I could do may save future headaches.

 

I seem to recall that some folks have moved all those electrical components out of the spare wheel well, and tucked them behind the panels on the driver side.

Jose

 

Check with your BMW Dealer. There was a recall to relocate the electronics which are lying in the spare tire well to relocate to the left rear area of the trunk up behind where the left rear panel comes off. Moisture can also be coming in if your rear wiper wash line cracks and leaks. It goes up to toe rear hatch underneath the rear headliner!

You can carefully push up the drain assemblies for the sunroof from underneath into the areas near which you are indicating water pooling. Clean the valves by blowing air up through them and into the sunroof area and getting any gunk out of the lines, then re-plug them in from the inside of the car and pull them securely into place from beneath. If you have large hands, it can be a pain in the @$#%.