Water leaking into passenger footwell
Thread Starter
Newbie
Joined: Feb 2015
Posts: 3
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2008 R350
Water leaking into passenger footwell
Every time it rains, water drips into passenger's footwell - and there could be 1/2 gallon of water overnight. Dealer cleaned a partially blocked drain from sunroof, but wanted $200 for just diagnostics. That didn't actually help. I've taped sunroof - water leaked. I've taped windshield - water still leaked. So, I'm puzzled as to where the water enters the vehicle. 
I'm pretty sure though that there is a drain pipe that's blocked (or disconnected) somewhere.. An advice on how to fix this leak would be very much appreciated! How much do you think it would cost to fix at the dealer or at an independent shop?
I'm pretty sure though that there is a drain pipe that's blocked (or disconnected) somewhere.. An advice on how to fix this leak would be very much appreciated! How much do you think it would cost to fix at the dealer or at an independent shop?
Senior Member
Joined: Apr 2012
Posts: 356
Likes: 66
2012 ML350 Bluetec, 2015 GL350 Bluetec
First off check all weatherstrips(door, window, sunroof, etc) make sure there's no damage.
Then remember tape NEVER helps with this kind of leakage. It should be a blocked drain but you can deal with it. Simply get a compressed air source, locate all drain ways and blow. Then test those drains with a plenty of water and see if the water goes to the bottom drain quickly. If not repeat the blowing until it goes smoothly.
Do this every year. Make sure no drain is clogged. This is a most effective way to keep rust off your car.
Then remember tape NEVER helps with this kind of leakage. It should be a blocked drain but you can deal with it. Simply get a compressed air source, locate all drain ways and blow. Then test those drains with a plenty of water and see if the water goes to the bottom drain quickly. If not repeat the blowing until it goes smoothly.
Do this every year. Make sure no drain is clogged. This is a most effective way to keep rust off your car.
Thread Starter
Newbie
Joined: Feb 2015
Posts: 3
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2008 R350
An update: car wouldn't shift out of park this morning.. into neutral or any gear. I had to have it towed to the nearest dealership, and it wasn't nice because the wheels were locked and the tow guy had to drag it up by force (soaped up a bit). I would be surprised if there were no transmission problems after this.
Newbie
Joined: Feb 2015
Posts: 6
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R350
When the AC air intake drain blocks up with leaves and general debri, it fills up during rain and spills into the passenger well.
You access this from the engine bay, 2 clips to remove the cover and drain can bee seen at lowest point.
Takes 2 minutes to do.
You access this from the engine bay, 2 clips to remove the cover and drain can bee seen at lowest point.
Takes 2 minutes to do.
Thread Starter
Newbie
Joined: Feb 2015
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2008 R350
Too little too late
I traded in this piece of ***t last week.. Enough is enough. The biggest mistake was not extending warranty on it when I had a chance, and thinking that it would be less expensive to pay out of pocket. Big mistake. The latest ISM replacement was $1.6k, and left front axle $1.2k just before that, and the list goes on and on. It's been the most expensive ride I've had, and least satisfying. So long. 
Member
Joined: Jun 2012
Posts: 229
Likes: 14
From: Akron, OH
2006 R350
The intake drain has a rubber check valve and that is the part that clogs. Rip it out and you never have to worry about it again. Dirt just runs out the bottom and water doesn't splash up high enough to get in. Have had mine out for years and have never had water get in again..
Newbie
Joined: Apr 2021
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2000 ML 320
You have to remove the fender. Run a 5/16 plastic hose thru the line and pull it out of the existing drain hose. I think the rubber hose that was originally installed deteriorated. There was no clog. Attach the rubber drain outlet hose and the leak is be fixed.
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