weird water leak that ruined tailgate module, from the gas cap water drain hole.

[bayareacat]

Hey Bimmer Gang,

I have an odd one.

The hole in the gas cap area, that’s meant to drain water, is quite literally flooding the truck of my x5. It’s ruined my tailgate module and I just replaced it, but didn’t install it yet as if I go to a car wash, it would just get wet again.

When I finally discovered it was wet, it was 8 inches up water flooded.

I can’t seem to find where this hole leads to.

Has anyone had this problem before? Any advise to fix?

I tested and confirmed that it is in fact this hole.

[tlow98]

This also happens on BMWs from the rear brake light seal area.

So, when you pour water in the hole, it comes in the car? It’s crazy they routed that through the car. Ugh.

[stocktree]

If you pour water in that hole, it should dump below, from behind the bumper.
Maybe a tube came disconnected

[imr3n]

I also noticed that during heavy rains, when I open either the driver or passenger door, water seems to fall out. luckily I haven't seen any water inside the car, it seems like it's just gets stuck under the door. not sure it that is normal or not.

[bayareacat]

Originally Posted by tlow98

This also happens on BMWs from the rear brake light seal area.

So, when you pour water in the hole, it comes in the car? It’s crazy they routed that through the car. Ugh.

Has anyone ever seen the tube route? Or have any pointers on how to find it?

I tired looking for a diagram but couldn’t find anything.

[Chilled]

Originally Posted by bayareacat

Has anyone ever seen the tube route? Or have any pointers on how to find it?

I tired looking for a diagram but couldn’t find anything.

Have you tried to shove some of that plastic lawn trimmer line?

You may need to remove the wheel liner to see if and what is going where. It's held in by plastic clips, but some of them are the BMW FU style where they are one use only.

[Clifton]

Originally Posted by bayareacat

The hole in the gas cap area, that’s meant to drain water, is quite literally flooding the truck of my x5.

I tested and confirmed that it is in fact this hole.

That hole under the gas cap isn't just for water, it's for draining fuel overspills. I'm shocked that drain, even if line is no longer connected, would remotely allow for possible water/fuel to enter the cab. Especially anywhere near the electronics.

I'm not doubting your test confirmation, but I certainly would not stop your search there. Several other threads here have tracked the source of water entry elsewhere. For example click then see post #8 found the issue was further up along the rear sunroof drain holes.