yeewiz

no. The car was dry for virtually a year prior, and the weather was dry in Dallas up to the week when I drove back. Then the ice and snow storm hit. The SA's explanation is when you are driving the vent opens to allow air to circulate. Water thrown up during driving doesn't go there somehow but gets channeled off. The SA said when not moving, the vent should be closed but mine was open because the vent was defective and water entered then. It didn't make sense then and still doesn't. Interestingly, the SA was certain it wsn't the drains from the sunroof.

My theory is when the snow and ice hit Dallas just before I left for SF and I was thrashing the car off-road in virgin snow and ice is when it happened. 6 - 8 inches of snow will basically mean your undercarriage and body is below grade. During my off-road excursion I backed into snow drifts and spun my tires and I got the car stuck in drifts for fun. With 4WD, I was able to drive out on my own. I think it was during these snow drift sessions when accumulated snow in the wheel wells entered the vent.

The vent is accessible from inside the trunk right below the fuse module. I'm going to open it up and take a look and trace a path to the trunk modules. The SA said I had a lot of water in the trunk. I'll definitely report back.

mmitev

Ok, that thing with the snow drifting probably explains the getting stuck of the vent.

But I still can not imagine how water flowing can get in there. It can flow along the rear quarter panel, slip behind the bumper and along the metal surface reach the vent. At that point it flows along the vent "ribs" if you will. However, they point downwards, so they direct the water away from the vent, not into it. Here I'm lost...

Or the other case, when the vent is stuck but you drive in the wet and water splashes up into the vent. That's also very weird, as a) as you said, all of this is behind the plastic floor cladding, so splashes can not reach the vent in a straight line, and b) as teh vent is designed to be open while car is moving, a lot of people should have the same issue of water getting in there.

I will also take a closer look at those vents next time I get a chance. But this SA explanation is growing to a proper mistery

Glad that they sorted it through the warranty though

Xman

Hi there!
Well here it is another sad story...I got a 530 2005 and exactly on Christmas Day in the morning I went to my car and I couldn't even open it because the battery was dead..So I thought the battery was too old and I bought a new one but the next day same thing happened and also after I replaced the battery I got a lot of errors(Active steering,Air bags,etc..) which I couldn't reset.I jump started the car but then the display went off and I didn't have any radio or navi nothing... On 27th I went to BMW( I forgot to say that I live in Germany) so I left the car there for a thorough inspection(energiediagnostik etc...) Next day they called me and informed me that my trunk was filled up with water and a display module was burned which cause my battery to die.Thing is with the errors that once you renew the battery you must go to BMW to do it because they have to register the new battery so you won't have those errors I got(the car must recognize the new battery). Anyway...my problem was exactly that piece that you said which is like a valve.The engineer explained me somehow different...that in case all 4 doors are closed simultaneously and some pressure is built up inside the auto it will be released trough that valve.He replaced me the display module put the original battery which was still good(I gave back the one bought by me) he dried my trunk and the bill was 850 euro.The module itself was 120 euro and the rest was labor... I got angry since it was not my fault what happened or how I drive the car, so I pressed him a little bit and he recognized that this is actually a factory faulty design and that monthly they have around 2 cars with this problem...and the water is accumulating in the trunk and then leaking on those electronic modules...and that I was lucky it was only one burned...I couldn't leave without paying but then I wrote to BMW Munchen about that, and the answer was that there is no problem with the car design...and the actual problem is that my 5 years old car is simply tooo old...So 58.000 euro car in 4-5 years is already considered too old..and that what happened to me is normal...Well I think this is not anymore Freude am Fahren ( driving joy ) but I don't have the nerves to write them back and argue cos I know I won't win..but for everybody with this model it is better to go by BMW before shit happens and put them to replace this piece or to do something to prevent any damage which will be expensive. I forgot to mention that since that day my steering wheel remained a little bit to the right side and is not anymore aligned with the wheels,I told that from the beginning to the engineer,to make it straight, he forgot,I noticed after 2 days that it is still in wrong position and when I came back he told me: It will cost you another 275 euro for 3 hours of labor....after my car stayed there 2 days ...I got angry and I left..and now I was searching on this forum how can I make it straight myself when I saw your problem and felt the need to write about mine .. but I just wanted to write to everybody that this is not a seldom problem and that it may arise anytime.

mmitev

yeewiz - see how the vent looks with the bumper removed. Its the big black box (ignore the red arrow).
I think water can only get there from underneath.. weird

yeewiz

mmitev, I understand what you are saying now. I took apart my trunk today and it's as you say: it's highly improbable a leak from that interior vent went directly to the wheel well. The battery compartment would have to have filled completely and then spill over into the wheel well. Even that's unlikely, the top of the battery cavity is 1" below body structure that separates it from the wheel well. More to the point, all my underbody cladding is in place, so even if I was spinning tires in snow drifts, there's no way my drifting episode could have thrown snow into the vent. So what about the technician's detailed notes? I think he could, of course, see the water sogged items, but he was under pressure to close up the repair and wasn't going to spend hours to locate a leak, so he just made up the reason in order to satisfy a factory warranty audit. I could still find some wet spots at the bottom of the wheel well but there was no water line to indicate a long-term standing water situation. You're familiar with this, but here's a picture of the trunk area including the vent, battery, and electronic modules for the archive and others. The vent is the black rectangle to the right of the battery and left of the fuses. The top of the vent is at the level of the trunk floor.

WHAT'S NEXT: I'm going to move those modules to higher ground. At first I had a brilliant thought, move the spare tire to the bottom and put the electronics on top of the spare. No dice, the genius engineers made the bottom of the wheel well smaller so the spare won't fit snug at the bottom. So the modules either go in that styrofoam circle that fits inside the spare, or, in the shallow felt lined compartment over the spare tire

WHERE'S THE WATER COMING FROM?: I don't know, but it reminds me of trying to find a leak in a house roof, it can come from anywhere. There was white tracing powder everywhere in the wheel well, but I saw no obvious leak trail. I felt all around including the pillar housing the roof drains, no luck. Actually, the more I look at this, how about the top of the rear bumper where it meets the opening of the trunk? It's only a few inches from the rear of wheel well and the most obvious and direct path. Maybe it's the power of self-suggestion, but the wire bundle there felt a trace damp and cold compared with the wire bundle in the rear pillar.

mmitev

weird things are happening here... and I thought I had sorted any flooding risks

yeewiz, alternatively you can install a water drain valve in the spare wheel well. AFAIK the LCI cars have one, precisely because of the flooding issues.

Rasmus

Very nive investigation... I think that you are on to something with the bumper and connection with the boot. What will actually happen when using a pressure washer (or very heavy rain) or similar at that area. Water will actually be "shot" into the gap with limited ways to escape, but in and to the side. This could create an over pressure lowering the effectiveness of seals etc. and thereby letting water into the trunk. Just my thoughts after your analysis...

mmitev

I have pressure-washed that area (where the trunk lid joins the bumper) multiple times, and haven't noticed any leaks. On my car at least.

Andy_E61

Hello,

the water comes either from
- the sun roof (no or bad drainage),
- the vent sealing (damaged) or
- the back light sealing (damaged).

Ongoing it seems that maybe the interior directs the water into the trunk.

mmitev

Andy, if you can tell us how the water gets from the vent or back light into the tyre mould, you will be a hero

Say it in German if you want, I can translate it