Clogged Sunroof Drain Fix for Mercedes W164 ML63 AMG ML350

Clogged sunroof drains on cars can go overlooked and cause a lot of issues if not maintained. In the case of my car I recently picked up, not only were they completely clogged with leaves, they had multiple leaks on the drain and pipe. If these leak or overfill, they can leak from the headliner back into the rear into the SAM unit. This would be a extremely costly repair if you took it to the Mercedes dealer to fix, hopefully this can help some with a DIY on the process. There is another video on KZbin for the W164 chassis which will help the process of removing the panels. This can also apply to other Mercedes SUV's.
I use iCarSoft for diagnosing issues which lets me connect directly to modules in the car and avoid using the dealer to pull codes. It paid off for me in the first use after I purchased it.
amzn.to/3hv6mUy

[@anthonyi1718]

A friend of mine works for mercedes. He said the tail light gaskets go bad on the ML’s. I had already gone thru a hydraulic tailgate pump and I was lucky enough to get to my rear Sam after a heavy rain storm. Had some discoloration on the motherboard but was able to clean it up. I shifted the Sam from laying flat to an upright position and wrapped it in some plastic. Very frustrating that mercedes never did a recall on this. I bought my 08 ML in 2010. If it was not for videos like this or forums we would be paying a lot more. Mercedes dropped the ball on this.

[@prclaudiojunior2012]

My GL 450 the rear part of the sunroof is leaking, rear drain are clogged looks like. So I have to take down the whole headliner like this? OMG... The guy who designed this did a really Great job right??? Great way to access the rear drain, genius!!!!!

[@andriibordundevcom2934]

Did you fix the issue with your GL 450? Was it the drain tube or just the lining rivets? Got the same issue.

[@AngusMcLean3]

oh man. Perfect. similar issues on my 350 and had no idea where all the water was coming form. rock on

[@paigers750]

I got a 2007 ml350 in feb and last week we’ve had heavy rain for several days& I park outside without cover. I didn’t really give credence to the fact my sunroof seal was sticking out during the rain & I haven’t put it back in place correctly. my 1st rain drive since getting this car, about 55minutes into my rainy drive my instrument cluster started throwing warnings, my wipers stayed on and my radio stayed illuminated but wouldn’t play and switches wouldn’t work. My first thought was it was water related & I couldn’t shake this feeling, water was coming in, somewhere. This has been going on after starting my drives ever since, I knew it had to be water related, but couldn’t figure out until today when I found water under my spare tire well and everything in my car seemed moist but not quite damp. Now I have a better starting place. Thank you!!

[@explorinlearnindoing5462]

Very good informitive video sir! 👌👍 I will check my sunroof too now I saw this! Please make more vids like these if you are working on your car. I subscribed 😊

[@ugochukwuebu8276]

This is a very common problem with the W164. Folks just don't have any idea where the problem is coming from. The autotechs just tell you it's from water but no one follows all the plumbing and information about that is sparse. Thanks for this video. I have basically changed 3 SAMs in 2 years; the vehicle was parked half of the time because of the same issues. Mine was always parked under a tree, so makes a lot of sense.

[@Draconius1000]

no one wants to fix that problem because its just expensive Dealer thought its a side glass, but i checked ml histories, they begin noticing and recall that problem after 2009 model But look like ML has a Defect by bad rubber glasses, i think the cheapest way to fix that problem, a new sunroof rubber

[@Youchoob1]

An interesting video I found here while looking for help with my W164 leak. After removing the wheel, mudflap and wheel arch liner I could find absolutely no trace of my sunroof drain in that area. On my car, which is rhd, I removed the rear right inner panel in the rear luggage compartment and could clearly see the hose from the sunroof in there. After unclipping the fuse box for some more wiggle room, I extracted the hose from its rubber holder with relative ease. On my car there was no need to remove the wheel etc and I figure many others might find the same thing hence my message. Keep up the good work..

[@Bond3594]

thank you very much for the info. I knew it is a common problem but owner just got notice when the ecu modules got malfunction or fried. the modules are at two major locations, one at battery compartment, the other one is at right back trunk. 😮😮😮😮😮 I am one of those owners and spent over thousands to fix the problem~!😢😢😢😢

[@CRUSTYCLAM1]

Good work, very informative video.

[@creativitybycarilyn6634]

I have a 2012 ML350. My first sign of trouble was condensation in the car and a wet seatbelt. I thought possibly I left the window down. After multiple days of non-stop heavy rain, the car was stalling and noticed water marks on the headliner. After dismantling the lower back area, we found a pool of water under the spare tire area. Water also went into the rear side panels near the tail lights. We dried the car out and it is running again, but we have to repair the leak before it starts raining again. This video is very helpful so we now know what take apart next. Turns out this is a common issue not just with Mercedes...our GMC Terrain is leaking too. TFS

[@philipsgarage]

Sorry to hear that I know it’s frustrating. I hope you get it all sorted.

[@sandeeppatel7998]

I hear a slosh of water in the rear somewhere. I do not know where it is? I check the trunk there was some water which I drained but when I hit the gas I could here a ton of water somewhere in the rear. Today I put a cup of water on the sunroof for the rear and saw that water was leaking from the seatbelt Pillar B I am assuming its called. Any idea where the water I can drain it out or where it is? Trunk and rear panel near the spare only had little water.

[@creativitybycarilyn6634]

@@sandeeppatel7998 Look under the spare tire. You will need a wet dry vac likely and might need to open everything up and put heaters or blowers to get it thoroughly dried. You will want to get the sun roof channels completely cleaned out because the get clogged causing water to overflow and go through channels in the car to the trunk where the wiring is under the spare tire. When you take the car to places other than the dealer for service, they do not clean out the channels in the sunroof. There are holes with rubber plugs under the car that can be unplugged to let trapped water out. If you don't get the water out, it can short out your wiring and cause the car to stop running.

[@sandeeppatel7998]

@creativitybycarilyn6634 thank you very much for the information. Very informative. I have checked under the spare tire there was little water. I unplugged it and water went out. The rear panel where the rear lights are had little to no water there on boths sides. Wonder where the remaining water is as there is a bug sloshing sound still. The front seats and rear seats carpets are not wet. I do see water coming out from the rockers. I don't know if that is normal. Wonder if water is stuck there. Any plug with the rockers? Any other place water can be? I will get the sun roof channels cleaned.

[@creativitybycarilyn6634]

@@sandeeppatel7998 I remember my husband taking the car out after unplugging the holes and stepping on the breaks repeatedly to help the water come sloshing out. He also parked it so the car would be sloped with the front higher than the back to help it drain out. We got ours dried out really good and it was running great again, but I no longer wanted the car because the wires had gotten wet. Many cars with sunroofs have the same problem. They are not properly maintained after warranty is up, they get clogged and cause water to come into the car, but the Mercedes ML 350 flaw is that the water goes where the wiring is. Our GMC Terrain also leaked water inside during the same heavy storm, but only some carpet got wet. This was an expensive lesson. We sold both of our cars and bought new ones at ridiculous prices during the pandemic. Lube places do not do thorough maintenance and getting a full service from the dealer or someone who knows your model well and what the dealer does for good prevention is prudent.

[@natprimus8379]

This has been an ongoing issue for my R320 Bluetec, which I understand is the same chassis as the ML. Thanks for the video. Over $2000 in water damage repairs, so now I have a place to start.

[@philipsgarage]

Thanks for watching, I hope you are able to get it sorted out!

[@paulm9400]

Looks like most common problem. I have same issue on my ML550. Thanks for video

[@KRBasch]

Very informative and highly appreciated!

[@philipsgarage]

Thanks for watching!

[@dougchristy4604]

Thanks for the video. I have a GL450 in the shop right now for a bad rear sam module that has water damage. Looks like i will be pulling the headliner down when i get it back.

[@philipsgarage]

Hope you are able to sort it out. You definitely want to check as soon as you get it back because the new SAM can get damaged if they don't fix the underlying issues.

[@andriibordundevcom2934]

Did you figure out the reason of the leak? Weak lining rivets or clogged drain tube?

[@scotthart6237]

I’m apparently building a new 2007 GL450… I have a ton of leaks. I’m trying to figure out that silly moonroof/panoramic window in the rear. Haven’t dropped headliner yet, but wanted to get a new seal.

[@tb5175]

06’ ML500 already replaced SAM a few years ago, whole area was wet, under tire, etc. Now I am noticing intermittent electrical issues like turn signal won’t work after replacing bulb. Original owner and only has 77K miles so I need to track down where water is coming from b/4 another rear SAM is destroyed. Mercedes really put that rear SAM in a terrible place. I have a sunroof (don’t use it) but good to know and will check to see if water drains by that back tire or plugged. I think it’s the rear tail seals. Never had issues until I didn’t have a garage to store it in. I avoid car washes at all costs and high pressure washing as it has thrown codes/electrical issues. BTW how many hours do you think you have into this job sealing up your baby?

[@Spamoonfire]

Hello! I don't know if you fixed your water leak issues, mine was coming from behind the plastic in the trunks, (00:06) there's rubber cap behind it that dried up over time and water was coming in and leaking on the SAM Card.

[@philipsgarage]

I got it sorted out, thanks for asking and watching the video. I guess theres alot of ways water can enter these cars, great tip.

[@guniseran]

No sunroof, no problems and more headroom

[@beterbey]

Hi, thanks for sharing. I don't understand how that big leaves get in to the drain. Is it during driving as the sunroof is open?

[@philipsgarage]

It happened from a previous owner. Its possible they may have been parking sometimes with the sunroof open underneath a tree, or when they drove and leaves fell in there.

[@beterbey]

@@philipsgarage Thanks 🙂

[@jaredlevy7193]

Does that tube tuck behind the metal or with the headliner down, would I be able to see where a leak may exist? unclogged the drain successfully, but still getting a small leak in the rear right panel.... or is it likely its just coming down from the headliner?

[@philipsgarage]

I didn't really need to move the tube too much in the position it was in. It should be above the headliner and then route on the side in the rear. If you have the panels removed its a good idea if someone can go in the car and look at the areas as you spray, from the sunroof or rear. Then afterwards see which area is wet and keep following it higher. I initially thought it was from a rear seal but the water was showing alot higher in the headliner showing me the water leak was coming in from a further spot up. Be sure to cover the SAM too during tests so you dont get any further water on it. It can be a little tricky.

[@blerimaliti4969]

Will this happen if the sunroof stays closed, because it’s my second SAM that i am replacing, raining in the summer holy shit. 😤

[@philipsgarage]

The leaves won't be coming in if the sunroof is always closed. I assumed a previous owner must have driven down roads where the leaves would fall in. But the seal around the sunroof could have shrunk from the heat and a little water could be coming in. It might be a good idea to spray the sunroof with a hose and then inspect to see if there is any water getting past the seal. You can do the same on the rear tailgate, there should be no water coming in at all if its properly sealed. I hope that helps, thanks for watching!

[@florentinamirela840]

Mercedes?!Wtf were thay thinking?

[@philipsgarage]

Definitely a interesting design but not too uncommon with sunroofs. I had the backseat of a E60 BMW I owned before flood due to the sunroof drains and seals. I'd prefer a car without sunroofs after the stuff I've had to deal with on them.

[@jitterbuba]

If I'd only knew this before buying an ML, I'd sure avoid one with sunroof. But she is here; it drives nice but I'm getting rear turn signal faults. When i hit four blinkers it is okay but when i actually hit turn lights, rear yellow lights don't blink but one row up... stop lights I think. Rear SAM will probably need an expert and once it is fixed I'm going to silicone and silvertape the whole sun roof and paint the sunroof knob red. How the hack they made such a lousy design job on a terrain vehicle. Do you have any idea how badly my SAM is already damaged... by the faults I'm getting?

[@philipsgarage]

No kidding, after having the issues with this car and a previous BMW getting flooded due to a back seal on the sunroof I'm not a fan of them either. I would recommend running the code reader, I use the icarsoft from the description link. It can go into each individual module to give it a more detailed reading than a cheap reader and tell you if there are current faults or previously stored faults. I may do a video soon going over it. I actually used it the other day with a check engine line, I got a fuel bank code. Doing some research it turned out that it was related to my dipstick coming out slightly, its amazing how sensitive the car can be. I'd recommend if you have another person who can help, do a leak down test with someone inside the tailgate. You may need to pull some panels back. But just spray down various areas with water, that should be able to help you see where exactly its coming in and possibly if you can reseal something. I've seen people mentioned they replaced the SAM, however I think in most cases it can be cleaned to fix it if there is corrosion using electrical cleaner. It looks a little intimidating with all the connectors that are going to it. However if you remove it you should be able to get into the case. The case isn't necessarily that easy to open because you have to pry tabs. But once you are in the SAM, you can spray and clean it with a toothbrush. Hope that helps!

[@jitterbuba]

@@philipsgarage It sure helps man. Just talking about it makes me feel better. Better not try that with my wife or I'll have to sleep in Mercedes. Thanks for the recommendation of this diagnostic tool. Looks like I better order one for myself as soon as possible and start working on the car before it gets even worse. You are very brave men to dismantle whole back of the car... we will see If I will be brave enough to do the same... TBH I can't really afford to just drive it to the dealer and get it fixed every time. I still have a torx set for my trusty w203 C220.

[@philipsgarage]

@@jitterbuba It it was a little daunting no doubt tearing into it, there really wasn't any info on it either. I hope it works out!

[@jitterbuba]

@@philipsgarage But still, hat down on fixing such complex problem... Just saw dipping emblem video... must be a joy and fun time spent... Wish I had time to think about side skids and dipping rims... my cart is seriously squinting and that is priority now. Not sure if I should wait for iCarSoft to arrive or go seek an advice from the doctor.