Water leak ?? How to test and unclog sunroof drains W/PICS
Thread Starter
Newbie
Joined: Oct 2012
Posts: 7
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2009 C300
Water leak ?? How to test and unclog sunroof drains W/PICS
Hello. I have an 09C300 with 36K and had water leaking inside the car from the passenger side where the headliner meets the A pillar.
It was also pooling water under the driver's side rug. I thought the pooling was from some BAD flooding we had recently in Miami. But then I noticed the rest of the rug was dry. I tried looking for solutions here on MBworld but found none. Most of the posts were recommending taking it to the dealer. My car is 3 months past warranty and that was out of the question. I did some research, grabbed my camera and dove in. Here's what I learned.
Seeing that the water was only pouring in on the passenger side and pooling on the drivers side something was clogged up. I tested the draining of the sunroof by opening the sunroof and pouring water in the opening by the deflector
Then look behind the front wheels and see if the water is coming out. On my car the was a little water behind the passenger side and NOTHING behind the driver's.
I then located the drains. They're in the front corners of the sunroof opening.
First, using a long piece of flexible wire I ran it down each one as far as possible without forcing it too much. You don't want to risk damaging the hoses inside the pillars. After that I got a piece of 1/4" airhose and trimmed the end to a sharp point.
Inserted it in the drain points and blew air through the drains until I could hear it coming out of the bottom.
I then did the water test again and SUCCESS !
Hope this helps !
It was also pooling water under the driver's side rug. I thought the pooling was from some BAD flooding we had recently in Miami. But then I noticed the rest of the rug was dry. I tried looking for solutions here on MBworld but found none. Most of the posts were recommending taking it to the dealer. My car is 3 months past warranty and that was out of the question. I did some research, grabbed my camera and dove in. Here's what I learned.
Seeing that the water was only pouring in on the passenger side and pooling on the drivers side something was clogged up. I tested the draining of the sunroof by opening the sunroof and pouring water in the opening by the deflector
Then look behind the front wheels and see if the water is coming out. On my car the was a little water behind the passenger side and NOTHING behind the driver's.
I then located the drains. They're in the front corners of the sunroof opening.
First, using a long piece of flexible wire I ran it down each one as far as possible without forcing it too much. You don't want to risk damaging the hoses inside the pillars. After that I got a piece of 1/4" airhose and trimmed the end to a sharp point.
Inserted it in the drain points and blew air through the drains until I could hear it coming out of the bottom.
I then did the water test again and SUCCESS !
Hope this helps !
Junior Member
Joined: Apr 2013
Posts: 56
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2010 C300
Good call. I would sometimes have to clear drain holes in my car, gf's car and so on. I noticed a lot of the times it's a spider that makes a web nest and then that collects all the dirt clogging it
By the way, love that color blue
By the way, love that color blue
MBWorld Fanatic!
Joined: Oct 2010
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From: Acapulco Mexico
2010 C300 Sport
Great thread and DIY fix for this problem. Congrats, should be part of permanent DIY collection. Need one for cleaning the windshield/wiper tray drains as this seems to be a more common problem.
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From: Long island new york
2002 slk 32 amg, 2013 c300 4matic sport
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From: NFLD
2017 C43 AMG, 2010 C350 4Matic, 9 Motorcycles
What os stopping you from using the OP's method? Need more info in prder to help.
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Joined: Oct 2014
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2012 Mercedes Benz C250 Luxury
I finally just got around to testing this, as I too have had bad leaks in my W204. Surely enough, it’s the roof drains, and not the windhisled or firewall drains. The passenger side is heavily clogged when water tested.
I had purchased some 1/4” vinyl tubing to do just this over the weekend. When insert the tubing into the drain opening, and pull it out, the tubing is covered in this thick black muck. It is very stick to the touch.
Does anyone have any idea as to why something this sticky would be in the roof drain holes? And its present on both sides, passenger and drivers.
Later on I’m going to try the air test. Let’s see if I have any luck.
I had purchased some 1/4” vinyl tubing to do just this over the weekend. When insert the tubing into the drain opening, and pull it out, the tubing is covered in this thick black muck. It is very stick to the touch.
Does anyone have any idea as to why something this sticky would be in the roof drain holes? And its present on both sides, passenger and drivers.
Later on I’m going to try the air test. Let’s see if I have any luck.
MBWorld Fanatic!
Joined: May 2015
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From: Miami, FL
2003 CL 600
It's just the gunk that builds up in there from water sitting and dirt in there.
Best thing to do is remove the wheels and the rear half of the fender liner, then remove the rubber closeout on the bottom of the drain tube. Flush them out with water until they flow clearly, then put the caps back on or leave them off completely. The original design doesn't drain well, and once any dirt gets in them, they clog and backup to the roof, then it leaks when it rains and floods the interior. Super common problem on the 204 sadly.
Best thing to do is remove the wheels and the rear half of the fender liner, then remove the rubber closeout on the bottom of the drain tube. Flush them out with water until they flow clearly, then put the caps back on or leave them off completely. The original design doesn't drain well, and once any dirt gets in them, they clog and backup to the roof, then it leaks when it rains and floods the interior. Super common problem on the 204 sadly.
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C230 2009
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From: Suburban Washington DC
1995 S280 5-speed
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Keep an eye on it still... You shouldn't get water to the drain tubes if the seal on the glass is doing its job. A body shop ripped-off my mother for $300 on hers, talking about the stuff you did as well as other. When I asked the guy what they did to verify the seal wasn't leaking, he want blank-faced.... Next rain- it leaked. I replaced the seal on the glass. It has been fine and dry for about 4 years now.
