BMW 4 Series F33 - Water Sloshing Sound Potential Fix - Save your Amp Before it Blows Like Mine!!

In this video, I show you how I drained the water that had accumulated in my BMW 4 Series Convertible. This really is not a video I would have thought I'd have been making, but I hope that it can help someone out there fix this terrible design flaw... Problem shared is a problem halved as they say!

Naturally, I tried to include a bit of 3D printing in this video, to show the versatility of this fantastic technology.

#BMW #WaterSloshing #Drainage

[tiptopchap]

This should be shared with every 4 series convertible owner - I’m driving around with my headphones after the amp went pop on a 5 yr old M4 that BMW want to charge me over a grand to fix. Seeking an amp repair person however thanks for sharing, it really should be a factory recall yet we will be waiting a long time on that from BM

[davenelson]

Outstanding! I had just bought my 2018 4-series convertible, and after a rain ... no radio.

AND: BTW - you *may* be able to fix your amp if it's been underwater. Try this: Remove the amp. Disassemble it down to the circuit board. Clean the board carefully with isopropyl alcohol (or contact cleaner). Then, put the board in your oven, and set it for about 175 degrees (F). Let it bake all the water away for a good 7-8 hours. Reassemble, and test. Fixed mine!

I'm a retired EE, did major stuff with PCBs & circuit board mfg. 175 F will not hurt anything. And, what do you have to loose!

Good luck - and THANK YOU for the video!

[TonyJvideos]

You've shown what's involved very well, Well done! Inspired use of the 3D printer! Bit of a bodge on the nut and bolts with the tape but it worked so all good. Using a bolt and a couple of (the right size) nuts locked up together I found easiest to "make" the 13mm allen key. For the viewers benefit, it only has to turn that little plug about an eigth of a turn to release the plug and it isn't hard to turn.

I wouldn't advise drilling the hole after you screwed the panel back up, you could potentially mangle the plug (allen key won't be much good if someone drills in too far and rounds the hexagonal insert off), it's easier to do while you have the panel down.
Easiest way to cut the plastic panels is with a dremel-type tool, goes through them like butter. I didn't even pull off the side skirts, just bent them down underneath by a couple of inches, and wedged them to maintain the gap while I made the cut-out in the plastic with the dremel. The advantage of making cut-outs over drilling is that you can make the hole large enough that you can remove the drain plugs in future (should you ever need to if they get gunked up again) without having to release any trim screws for the side skirts or under-tray.

A little explanation of the theory. The side skirts and under-tray don't have gaps for the drain holes because BMW have used the same ones as for the coupe, which doesn't have opening rear windows, they're sealed, water can't get into that section so doesn't need a drain plug. BMW should have designed specific side skirts and under-tray for the convertible with cut-outs for the drain plugs either side but they didn't. Purely a design oversight (mistake).

The last thing to mention, which none of the videos show (I can't talk, I didn't even make one, lol) but what people will be asking is how does it fill with water? Essentially over time the rubber seals on the rear windows (which open on a convertible) don't seal properly and let water in. Obviously heavy rain at the wrong angle will penetrate, and something people should be aware of when they wash their cars, particularly if using a jet wash. They're essentially filling up their own quarter panels with water without realising. Car doors always have drains at the bottom in case water ingresses past the window rubbers, the rear panels on convertibles same applies. To keep water out people should replace the rear window sealing rubbers when they get old / hard / brittle enough that they no longer prevent the ingress of water. Dirt and gunk gets lodged down the gap accelerating deterioration and just as windscreen wipers deteriorate, they won't provide a good seal against the glass forever. Apologies for the long comment, but hope that fills in the gaps.

[Paul-hz]

This is a brilliant video - thank-you. How on earth have BMW got away without doing a recall? Amp and roof retraction seems to be damaged!

[darrenaxe]

Had mine from new. Today notice sloshing sound (Music off for some reason today) 😂.
Checked out your video. Exactly the same outcome. Mod done, slightly different, same result. Easy access now to the drains. What I don’t understand is why BMW didn’t make them easy to get at.
Thanks for the video. Been a great help. 👏👏👏

[chriswalsh]

Just heard the sloshing on my way home from work tonight, first video I found was yours!
Spot on mate!! It’s a good ‘how to…. ‘
Cheers 👍🏻😉

[simonhobson]

Really valuable and informative video! My F33 convertible has been dripping for weeks and this explains why. The dealer conversation was not useful - this video was! I shall be following your example of unblocking and then adding a drain hole. Many thanks.

[brianlloyd]

I've had this problem for about 2/3 years, tried with a few YouTube videos myself and always had to take to a garage. Youre video was great and feeling very proud of myself that I've drained it myself this afternoon! My problem was that I wasnt pulling that side skirt towards me before! Thanks for the video!

[matthewwakefield]

Brilliant video thanks. Just bought a 4 series cab and noticed the sloshing. On this mornings job list! Thank you

[guysmets]

I noticed this a while ago, that after it rained, there was water under the car until the day after. So very near to being blocked.
Thanks for the great tip. At least I could fix it before it got too bad...

[motorbiking]

Great video, I've had this problem for a while and yours was the only video that showed the drain plug fix

[PrinceVidz]

This problem just happend to me, water slosh sound in back panel. Exact same problem you are having. The reason the water gets in there is because of the back window rubber has gotten bad. Its deformed to the point where water slides in to the back. I tested it with a bottle of water on the bad side and the water gushes in to the car. On the other side where the rubber stil is good the water glides of off it. So i would imagine the long fix is to replace the back window rubber. After fixing the drain plug of course. Excellent video. (m4 f83)

[tomdarrohn]

Thank you! Same exact problem on my 2018 430i convertable. I was able to improvise by using a bolt head (as you recommended) and just turned it with a pair of vice gribs. Probably drained about 2 liters of water between both sides. The driver side was worse. Unfortunately what led me down this road was the blown amp, finding it submerged in water 😩
Update, there is a service bulleting from BMW on this: 513316. They say to leave the drain plug out after removing it. Don't re-install it. I also saw on other threads to cut both plastic overlays to allow the water to flow and not cause dirt/grime building up to prevent drainage.

[daveb]

My 2015 F33 has lost 1 amp and also over time flooded on the battery side which corroded the main cable terminal to the front of the car and one day it just wouldn't start. Both expensive to rectify by dealer. Interestingly at some point they also drilled the holes (as per BMW Service Information Bulletin SI B51 33 16 V2) but that did not stop the problem - maybe the holes were in the wrong place or the drain plugs just got blocked anyway. Also they never even bothered to tell me they'd done this - I only knew when I found the holes. Anyway, a few months ago I removed the plugs and on both sides got as much water out as in the video. I haven't put them back in - as far as I can see they could just get blocked again with gunk even with a hole beneath and can't see how any water off the road could go upwards and cause a problem. So far so good. Note that another tell tale sign I had was the rear window coming up with drops of water on it even when it had not rained for a while.

[macmad]

This brings back memories, I had same issue on my F33 last year, full of water, drilled through the valve and gallons of water came out, unfortunately it causes my window regulator cable to snap, so had issues getting the roof up, all got sorted in the end, required a new window regulator, and was installed.

[johnoates]

Best video I've found to help identify the location of the drain plug, now resolved thanks for the info 👍

[Stuff]

Thanks for the information, we just drained about 10gal from the back. New holes made it drain much better, the sludge buildup will happen so make this a maintenance item with your oil changes and clean that plastic part

[richardwood]

A brilliant video. We heard sloshing water noise in my wife's 2015 420d convertible a few days ago. I accessed as per the video and did the offside first and gallons of water escaped. I then did the nearside and it seeped but no gush. I then prodded up with a screwdriver and saw a plug of debris slowly lower itself before the torrent. Obviously the debris had been accumulating more on that side blocking off access to the drain hole totally. I agree - an abysmal design by BMW - and I have always been a BMW fan...

[kevindixon]

Just uploaded a short vid of my wife’s 430i convert. Thanks for your vid so I knew how to fix. I found that a bolt with a 9/16” head fits in the drain plug so I used the bolt with a stop nut as a wrench. Thanks again.

[salesmindestandbusiness]

This is great thank k you for sharing.

I thought that they had forgot to add a baffle on the fuel tank but it would appear it’s a water ingress/drainage issue.

My entertainment system stops every time I hit the breaks