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

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 👍🏻😉

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!

Having heard the same water sloshing about and seeing dripping its clear i will need to complete this fix.. very helpful Callum

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.

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. 👏👏👏

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

I've had this problem for about 2/3 years, tried with a few KZfaq 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!

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.

Thanks for sharing! Worked perfectly. What an insane construction… Many thanks!

Great video, such a simple job that a MUST for any F33 owner. Only thing I would add is to try and flush a bit of water through with the plug out, I cleaned the plug but had a ‘slug’ of dirt stuck further up the drain hole waiting to immediately re-block the plug…..Terrible design from BMW

Thank you so much, finally fixed that sloshing sound!!

Thanks brother! God bless you! I made it today, same thing! Unbelievable!

Thanks a lot for the video. I’ve been on the edge of pulling the trigger on a 4 series cab and so pleased I saw this. I believe error from BMW, great fix though. Thank you.

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.

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

Perfect - thanks for a great video! Thought I could hear sloshing in the passenger side sill of my 440 convertible and was on my way to the garage to let them investigate (but it was closed this weekend) when I had multiple electrical failures/warnings on my dash as well as losing my iDrive display completely, most button controls, audio - and my boot wouldn’t open at all (had to manually release it from inside the car). Boot carpet fairly damp, & lots of condensation in the car. Hope I haven’t killed the amp & it’s just fuses. Meanwhile, I’m running a dehumidifier overnight to try and remove most water vapour. We’ll see!!

Your instruction was spot on, although I had to borrow a 13mm Allen key from my local very friendly ATS Euromaster as it is not standard size. I drained litres of water from both sides of my car and removed the plastic plugs completely. Unfortunately I found your video after the water had sloshed over and drowned my boot and blown my amp :-( so still a costly repair.

Just sorted on my 420d soft top. Crazy design flaw! Thanks!

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!

Great video. A job for tomorrow. Thank you for making it.

Thanks for the video. Just fixed the same problem.

This is exactly what was going on with my e70 x5. Could not find the course of the water sloshing and finally took it to a shop and they did something similar to this and drained almost the same amount of water

Thank you so much for your very helpful video. I had that whooshing sound behind me and water onto my shoulder rear window well full of water. And simply un blocking hidden drain water poured out. Problem solved.

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.

Great video, very helpful. Thank you.

Thank you!!! Fantastic video 😊

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)

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.

This video helped me out! Thanks a lot!

Thanks for the video. Just had my 435 drains cleared by a local BMW / Mercedes garage. The car had the water swashing noise and your video put me onto the problem. Cost £106 and they did the mod so the drains shouldn't get blocked again. Fortunately the amp and surrounding area was dry, although they reckoned the got 2lts of water out of the drain. Thanks again!

Excellent video. Thanks a lot

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...

That's mad, I've just bought an F83, gonna get it up on the ramp tomorrow and get this done!

This is crazy and exactly what is happening with the 2020 440i convertible we just purchased. I heard water slashing around a few days ago and have found puddles on our garage floor. Thankful we're under warranty so no fees.

Thanks for the video. I had the same problem with a Serie 4 Cabrio, when i stopped i could hear water splash on rear side, now i have no watersloshing.

Same problem, im gona solve it tomorrow thanks

Brilliant, thanks Callum :-)

Holly sh1t!! My rear window stopped working. Was looking for causes and fuse number to check and found this! I also heard some water slosh but thought it was just a water bottle in the back. Now I know! Warranty claim on its way ..

Finally someone who shows how it's done. I just did it on my cabrio as well. My back windows mechanism was completely rusted and had to pay 1000€ to have it replaced... Also thinking to blame this on BMW but I'm lacking the time and emotion to start it. PS. I think you need a 14mm hex key as the 13mm seemed slightly too small

Thanks, a lot.. u saved me a hefty bill .... 530 gt 2012 has no drain plug, For some reason BMW decided to seal the opening coz i could see the plastic bit but no screw..... so I had to drill a hole to get the water out... but my Rear Passenger carpet was getting soaking wet .... leaving it to dry now.

Thank you so much. My car collected so much water the sound system went out. The dealership quoted me $3700. Did this like you showed in the video and worked just fine.

Great video. How did you remove the side skirt?

Thank you for the video and info. I have another question, when i first drove my car after the heavy rain and heard sloshing sounds, there was no water in the car anywhere but i heard sounds from the roof as well, when i forced the car with heavy braking, some water came in from the roof middle section, but that was it. Where is this water exactly filling and whats the risk of it filling inside? I opened the top and there was no water anywhere on the roof either.

Thanks for this. What potential damage will it cause tk electrics? Where has it all cone from rear quarter or boot?

Hi great video, easy to fix, the only problem i found was when everything was back together, went to start vehicle and battery was flat. Is there anything that could have caused this.

Hi... can you not leave the drain plug out? Would it cause any issues if you don't put it back in?

Nice video even if a bit different than your normal content.

This is obviously a design fault and, as some have pointed out, is a possible electrical hazard caused by modules in the boot shorting out, directly above the petrol tank. This problem should be a BMW recall as it's potententially dangerous.

Do we have to do it on both sides? I am driving a RHD model. Do I have to unscrew the left side skirt too? Also does drilling a hole expose the car body to rusting?

Is there gonna be an issues if I just keep the drainage plug out and drill the said hole

This is absolutely ridiculous. Im having this issue now im very surprised this issue is not big enough for bmw to cover the issue. Water can get into the trunk where the amplifier is and cost $1500 to fix. This is crazy to me

Insane😮 I assume this is the same for the F30/F80 3 series?

Hi, after drilling a hole does the water come out or does it still hold up in the quarter panel?

For a 3 year old video this is still relevant. This needs doing if you haven't already. Does anyone know if there is a drain the other side of the rear wheel arch in the boot, (underneath towards the rear of the car) as maybe water can slosh over if full enough?? Thanks again. 😊

Do you think the F30 saloons have this same problem?

Hi, Do is it the actual drain plug you drilled the centre out of please, if so would it be easier to do this while you have it out of the car? Brilliant help your video is as my window stopped working and now the roof, removed the rear quarter trim to find the quarter filled with water right up to the top where the window is. 😡

Thanks for great video ! Is this more prone with f32 / 2 door models ? I have f36 and never had issue ever !

I've a 2016 F32. Not a convertible and doesn't have a sunroof. I pulled the side skirts off over the weekend but couldn't find a drain hole. Presumably its only for convertibles or perhaps cars with sunroof?

I’ve done same to my f33 last week and didnt put back drain plug, I just left the hole open, you guys think is it gonna be problem in the future ? 🙏

Yikes! Just bought a F33 440i... I'll be checking this as soon as it's on the driveway. Absolutely mad how much water came out of that! Is there an argument to leave those drain bungs out? They look like they could further the obstruction of water and debris

What is the size of this screw

Where's the water come in from? Dodgy rear window seals?

Hey, having this exact same issue with my F83 M4. Would you consider selling your 3d printed tool? Thanks

Hi Callum I have just purchased 68 plate 420i convertible, do U know if this has been fixed on the newer models or do I need to do this also :(

I have left the plugs out now. The skirt/side plan provides enough cover

Dude thanks so much for this video… i already lost my amp… my roof has a missing piece on each side now… just broke and came off the roof… 🤬…. If rains … i have a pool in my car!! Insane… If you have any suggestions.. i take them all! Thanks so much

Does this affect the F31 aswell? I can hear sort of a splashing sound from the passenger side (right side in germany) when it rains

The BMW dealer did something similar to mine. Drilled a 12mm hole through skirt and tray and I can stick a wire up the drain to clear it now. Shocking.

Hi Callum, thanks for sharing this.ive got a 2016 420 hard top convertible and fear this might be an issue with mine. I’ve never experienced any symptoms and there aren’t any sloshing sounds even when I do an emergency stop on an upward or downward slope. I ve checked the rubber sea.s around the rear windows and they don’t seem to be slack. I don’t have any Mechanical expertise nor any tools or a Jack. I will get my local mechanic to check it when it’s next in for new tyres soon. any idea if later models than yours had a redesign/fix?

I have a 2015 m4 convertible, when driving slowly I hear the water. 😓 . Thing is i hace carbon fiber side skirts installed, id have to remove those, THEN undo the bolts for the sides. Is it possible to just remove the under panel and get to the drain hole??

Thanks for the video mine needs doing, the main issue is the how the water gets down there in the 1st place, I believe its the rear window seals, any information on replacing the seals

My back window regulator and motor was fried from the water. Would it be OK just to remove the plugs? The side skirt would protect it.

Great video pal. Please can you advise whether both sides were filled with water?

Thanks for this video, has there been any official answers by BMW on this issue ? I am facing the same now with failing window and convertible roof due to water issue :(

Heard water in my F36. Had my 13mm Allen key bought off Amazon for £6 but no release valve at that location. Pity!

How old is the car btw? I did the mod when I read about people having problems for future-proofing but I didn't have any build-up of water. Mines 2016. Most cases I've heard of seem to be slightly older. Just trying to establish the predicted longevity of the window sealing rubbers.

The only reason I can think bmw covers it up is to prevent the dirt and debris that flies around under the car from getting in there and if that's the case they should just put a mesh filter over it similar to something like people use in the kitchen sink

nothing like a bath for electronics, motors, sensors, wiring & it freezes in winter depending where u live. Was all that water in the rear quarter panels & lower section of boot?

I have almost the same issue,but the water on mine is getting stuck above where the small window stores itself after lowering it! No Idea why

Hi how does this prevent damage to the amplifier? Many thanks

Sadly this is an issue BMW have had for years. E9x series drivers have this issue as well, where the drain plug is blocked by trim pieces and it cannot drain and gets clogged and then causes flooding inside the car. This can lead to flooding in and around the battery, which leads to corrosion on the power terminals, which leads to major electrical issues, and in some cases has killed cars completely.

Great video Callum. My left side boot compartment has just flooded, rendering the amp useless. No sound in the car at all. When you replaced the amp, did you go with the same one? Did you have to buy it from BMW? Or did you find elsewhere? Or would be possible to go for another make of amp? Conscious that BMW are likely to take the p*ss on this one…..

What symptoms did you see when your amp blew?? Loss of audio from radio/speakers?

Anyone knows the part number for the drain plugs ??? Cant find it 😮

Hello everybody. Is this the same for f36? I opened my side skirt and nothing under it. There's no draining hole. A help would be much appreciated.

Any chance u could show a video of how you get the side skirt off? Mine seems absolutely solid and doesnt move enough for me to access the drain plug properly.

Thank you for this! I need to perform this fix in my wife’s car. QQ: was it a 13mm hex or 14mm hex? I know the 3D print was 14, but I thought I heard you say 13. Thanks!

Thanks for the vid - Sorry if asked already asked before but why not just leave that plug out completely ? Does it need to be there and keep getting clogged ?

Can we just remove the plugs? Any problem if we just remove and thow them?

Would it not be better to just leave the drain plugs off so water can easily escape? Or am i missing something?

Why not do away with the drain plug? Seems that’s part of the issue as well, getting clogged with debris

Is this just an issue on the f33 convertible or on the f32 coupe as well? Seems mad that a modern has this issue!

Isnt this only prone to the convertible models? Never had this issue with my f32 coupe but know its a big issue with the convertible

Great video but was your carpets wet inside the car. Because mine are trying to find the problem 👍

Could this cause a damp smell in the cabin?

Did you hear the sound of water in the cab of the car while driving or? How did you find out it was gathering right there? Thanks!

Sorry, watching with no sound on a train. Did you drill straight through the bung?

Hey great vid! I have done the mod (removed the black bungs either side) however I can still hear water sloshing? Any ideas? Thank you

Did you have to take off the side skirt to access the drain plug?