We have a 2008 X3 3.0si, purchased as a CPO in 2012, with currently 68,000 miles on it. During recent Biblical rains (in the Pacific Northwest), and constantly since then, it began to leak somewhere in the upper left-hand rear area just inboard from the rear hatch. Never leaked anywhere before. There was 2-3 inches of water all through the cavities in the rear, covering and rusting the tools, shorting out the battery, and soaking all the various carpeted surfaces as well due to capillary action. The body wall underneath the access panels is wet all the way up, but the headliner is NOT wet (pulled out part of the headliner to assure it was dry inside) so the source must be a little below the headliner. There are many electronic modules throughout the rear body that appear to be very vulnerable to water damage. After hours of disassembly and inspection, I cannot find the source of the leak. There appears to be a rear sunroof drain tube running from top to bottom. I cannot find where it opens on top in order to check for clogs or clear them out, and I have not located the lower end of the tube due to daily rain and a wet driveway. AllData suggests the leak may come from a taillight seal (but the leak originates MUCH higher up), or from the grommet where the wiring harness for the tailgate exits the left upper corner of the hatch opening (mine is tight and intact, and cannot possibly pass so much water so quickly). Google and YouTube videos suggest this is a very common leak, but provides no real solution. Can anyone help?
