When I bought the 128i, I considered myself lucky. I mean, what are the odds of buying a 15-year-old N52-powered BMW and not finding any oil leaks in the commonly known trouble spots? I even contemplated buying a lottery ticket or wagering large sums of money I didn’t have on random sporting events, just to see how far I could ride this streak of good fortune.
As time went on, however, I discovered that my E82 did develop a few leaks—they just weren’t related to automotive fluids. This poor little car was struggling against one of nature’s most relentless forces: water. On second thought, cancel those bets.
In one of my previous posts, I mentioned finding gallons of rainwater pooled in the lower right side of the trunk, where the TPMS control module is located. I’m happy to report that after drilling a couple of drainage holes in the area, I’ve had no further issues with the TPMS module or water accumulation. However, that doesn’t mean I gave up on understanding how the water was getting into the trunk in the first place.
One potential culprit was the rain seal on the right side of the rear windshield. I noticed a portion of it dangling loose, not properly tucked into the crevice it was meant to guard. So, I did the simplest (read: laziest) thing I could at the time—I tucked it back into place.
While investigating the trunk area, I also noticed an issue with the trunk latch. Closing the trunk and getting it to stay closed felt like playing Whack-a-Mole—every time I thought I’d nailed it, it popped right back up.
After staring at the mechanism for far too long, I realized the problem seemed to be a small plastic piece interfering with the latch. Upon closer inspection, I noticed a gap between part of the latch and this plastic piece, where the plastic was slightly bent to the side.
So, I ordered a used latch from eBay for a few bucks and swapped it in. I also had to transfer the stock cables since the unit I ordered was from an E90, and the cable lengths were different. No big deal—the cables swapped over in about two minutes.
The entire job took around 15–20 minutes and was pretty straightforward.
When I went to shut the trunk, I ran into the same problem. Doh! That’s when I realized the striker and latch weren’t perfectly aligned. I spent a couple of minutes adjusting their positions and got them as close as I could. Now, the trunk shuts easily and stays closed! It’s actually a bit tougher to open now, but I’d much rather deal with that than have it pop open while driving down the road.
I did wonder if the trunk not fully closing was the reason water got into the trunk in the first place. I can’t say for sure, but what I can say is that I haven’t noticed any issues since. At this point, I thought I was in the clear—victorious against the villainous tirade of water. I ran the car through high-powered touchless car washes without a hint of fear. All was well until, one fine day at the car wash, the H2O struck back with a vengeance!
Out of the (translucent?) blue, during the high-pressure portion of a wash, water began pouring into the car’s interior from two separate locations—one of which was the right/passenger side A-pillar area.
I inspected the passenger-side sunroof drain tube and spent some time working on it, using a piece of wire and an air compressor. I also removed one of the plastic underbody panels to monitor the drain tube underneath the car, giving it a bit of a clean as well. While the lower tube wasn’t too bad, the roof drain tube was stuffed up worse than Uncle Jimmy on free taco night!
Before cleaning the drain tube, I noticed that pouring water around the roof area caused it to puddle and slowly leak into the interior roof and A-pillar. After cleaning out the tubes, however, the water drained immediately with no signs of pooling or leaking. Leak solved! Oh, the sweet taste of victory! But we weren’t out of the woods yet. There was one final leak to defeat, and this one was a real fighter.
I first noticed it during the same high-powered touchless car wash. Glancing over, I saw soapy water slowly seeping into the passenger-side footwell, right behind the glovebox.
Initially, I was quick to blame BMW, hurling obscenities at the poor German car like a madman in the midst of a verbal onslaught. But after inspecting the issue, I realized it wasn’t BMW’s fault this time.
After scouring the internet for answers, I determined that water was leaking into the passenger-side front footwell (behind the glovebox) via the blower motor.
I removed all the layers of cowl trim from the engine bay and discovered the culprit: the rain seal along the metal edge above the blower motor was completely detached on the passenger side—not even connected! Unfortunately, I didn’t take a photo of the detached seal before reattaching it, but I did snap a picture of the repaired seal to help anyone who might encounter the same issue in the future.
For the record, I’m referring to the removable rubber seal that runs along the metal edge in that area. When the seal was hanging loose, it appeared as though water was running directly into the blower motor, ultimately pooling in the passenger-side footwell.
Once I removed the cowl trim, it only took a minute or two to reconnect the seal to the metal edge of the car. Judging by the design, it seems this rubber seal functions as a rain guide, channeling water toward the edges of the engine bay, where two drain holes allow it to flow out.
After reassembling everything, I tested the repair by soaking the car with a garden hose—and not a single drop of water entered the cabin! Granted, I wasn’t using a high-pressure washer, just a standard garden hose, but the results were promising. During this process, I discovered that someone had previously replaced the windshield. Unfortunately, whoever did the job went overboard with the sealant and didn’t bother cleaning up the excess. Take a look at the massive blob of sealant circled in red below, which we’ll call Exhibit A.
This wasn't a problem limited only to one side. The carnage continued on the driver's side as well.
This resulted in the cowl seal never being fully seated/sealed against the windshield.
So, I did what any red-blooded American would do in this situation. I grabbed a knife, determined to defend the honor of my poor mistreated E82.
I used a scraper and a razor blade to trim the excess sealant off of the windshield.
I later trimmed the excess sealant from below the windshield, taking care not to remove too much and risk creating another potential leak. When I reassembled everything, I noticed that reinstalling the cabin air filter caused the weight of the filter to pull the cowl slightly away from the windshield—somewhat undoing the work I had just completed. Upon closer inspection, I realized that the cabin air filter housing is supposed to have two plastic tabs to support the weight of the filter. Unfortunately, these tabs had long since snapped off, which is a very common issue with these cars.
Now, a rational human being might do something reasonable, like ordering a new cabin air filter housing. But not this guy. I took this opportunity to start chopping up, drilling and bending some metal to make my own brackets. Take that plastic tabs!
No, this is not a pretty or remotely elegant solution. It absolutely won’t win any car show awards. But it worked! And unlike the OEM plastic tabs, these brackets won't snap off at the first sign of pressure.
After I buttoned everything up, I noticed there was still a small gap between the windshield and the cowl seal in a few spots. Fortunately, it’s only a fraction of the size it used to be! I can now get the seal to lay flat against the windshield, but it seems slightly out of shape after being misaligned for so long. I’m hoping a hot, sunny day will help "melt" it back into place.
Now came the moment of truth. Had all my finagling with this old, worn-out BMW actually stopped the water leaks? There was only one way to find out: I had to make it face its old nemesis—the high-powered car wash.
I rolled in, nervously watching the passenger-side footwell, bracing for the inevitable trickle of soapy water and the accompanying torrent of profanity. The high-pressure spray hit... and the interior remained bone dry. Leaks resolved!
The final scoreboard: Idiot in the Garage - 1, Water - 0.
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