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2001 S500
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28 Posts
Discussion Starter #1
When I drive my 1996 C220 through a car wash, water comes into the passenger area from below the dashboard. I have pretty much concluded from my research so far that this is due to a clogged drain but when I remove the screens and inspect the drain hole in the trough ,it is clear. I tried poking something down the hole to see if there was a blockage but ran into a turn or something a short distance in.

There isn't sufficient room to find the drain or to get at it so I am at a loss as to what do to next. I am stumped. I have read a lot about the problem but nothing about the solution. Can anyone tell me how I can locate and clear the drain pipe.. or tell me what solution I need to pour down the hole to dissolve the debris. This is very frustrating.. thanks
 

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1996 C280
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151 Posts
I had this happen once while i was running the A/C during a car wash. I assumed the water was coming in the air ducts. The next time I turned on the recirculated air option and no water came in. maybe a fluke, but worth a shot. in my mind i thought the water was coming in the fresh air duct and by activating the recirc I was cutting off outside air thus no water could get in.
 

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1995 C220 102k
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588 Posts
Mine did it once... one time - never did it again...
 

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2001 S500
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28 Posts
Discussion Starter #5
The windshield is the original. I spoke to MBZ customer care 800 number and they weren't much help. Told me to look and see if the cabin filter was wet and if it was, to follow the vent to the end to see if i could find a leak. If dry, he said take to a technician.

I removed the screen at the base of the windshield and the trough and drain appear clean.
When I pour water in it, it slowly comes out the bottom. I am told that is how it's supposed to do it by the MBZ guy.
 

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95 C280, 89 300E, 94' E320 Coupe, 91' 560SEC
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1,095 Posts
do a search on the forum. This was just discussed two-three weeks ago on the forum
 

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1995 C280 (165K mi)
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1,595 Posts
you could get some water, put some food coloring in it, using a turkey baster carefully pour water into the drain pipes to see how much and where the water falls out of. keep a bucket inside in case it gets into your cabin. systematically eliminate each drain pipe. remember sunroof has one or 2 drains as well.
 

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2001 S500
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28 Posts
Discussion Starter #8
Well, i removed the cabin air filter and it was wet so now I just need to figure out how it's getting into the air ducts. I looked inside the filter box and didn't find any thing wrong so tomorrow, I will go out and once again pour even more water into the trough in front of the windshield to see if there might be a clog I can't see. It looks perfectly clean but I can't imagine what else it can be.
 

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1995 C280 (165K mi)
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1,595 Posts
when you pour a gallon on the top does about a gallon come out through the bottom quickly?
 

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2001 S500
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28 Posts
Discussion Starter #10
Problem discovered and solved

Well, thank goodness for persistence. With no help from the Mercedes customer service line, I have finally gotten to the bottom of the problem and fixed it for nothing.

I am most disappointed in the folks at the Mercedes hot line. I phoned them twice and got no help. The first time I was told to remove the cabin air filter and to find the fresh air inlet myself.. something not possible unless you are a contortionist.. and then only maybe. Why he wouldn't tell me.. is beyond me.

The second time, a different guy told me where the air comes into the car but didn't help at all to resolve the problem.

The problem was a clog that could not be seen in the water trough drain on the passenger side of the car. Neither guy at Mercedes could tell me where the water outlet really was located. They said it drained out the bottom, which was bogus info. Finally, I filled a gallon jug with water and kept looking till I found it. The drain is about an inch to 1.5 inches in diameter and extends from the front of the plastic catch trough under the hood at the bottom of the drain on the side facing the frond of the car. You can locate the drain hole it by removing the plastic screens extending forward from the bottom of the windshield and looking in the trough.

It doesn't look like a drain really but has a flexible rubber flap over the drain. When you pour water into the trough, you should be able to see water flowing out then down to the ground. It should flow freely. In my case, it was trickling out. (I was told by the Mercedes CS guy that it is supposed to trickle out.. another misstatement)

I reached down with a long screwdriver and carefully pulled the flap open and a sizable chunk of wet organic debris came out and the water started flowing freely. It was as simple as that. I put the car back together and ran it through the car wash with my fingers crossed and not a drop came into the car.

I simply can't believe that the folks at MBZ didn't tell me about the nozzle and the flap and that from time to time it can get clogged... even if it doesn't show at the top of the drain. It seemed to me that they were more interested in getting me into a dealership to have it looked at as if I wanted to spend a few hundred dollars doing some unnecessary repairs when it was a 10 minute fix.

In total the repair took me two days to find (working a little each day since it was in the single digits outside and not that much warmer in the garage) and but a moment to fix once discovered.

Props to me and shame on Mercedes. Hope this helps save someone else from an equally frustrating time.
 

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1996 C220 Elegance / 1991 190D 2.5 / 1991 300SEL
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118 Posts
Well, thank goodness for persistence. With no help from the Mercedes customer service line, I have finally gotten to the bottom of the problem and fixed it for nothing.

I am most disappointed in the folks at the Mercedes hot line. I phoned them twice and got no help. The first time I was told to remove the cabin air filter and to find the fresh air inlet myself.. something not possible unless you are a contortionist.. and then only maybe. Why he wouldn't tell me.. is beyond me.

The second time, a different guy told me where the air comes into the car but didn't help at all to resolve the problem.

The problem was a clog that could not be seen in the water trough drain on the passenger side of the car. Neither guy at Mercedes could tell me where the water outlet really was located. They said it drained out the bottom, which was bogus info. Finally, I filled a gallon jug with water and kept looking till I found it. The drain is about an inch to 1.5 inches in diameter and extends from the front of the plastic catch trough under the hood at the bottom of the drain on the side facing the frond of the car. You can locate the drain hole it by removing the plastic screens extending forward from the bottom of the windshield and looking in the trough.

It doesn't look like a drain really but has a flexible rubber flap over the drain. When you pour water into the trough, you should be able to see water flowing out then down to the ground. It should flow freely. In my case, it was trickling out. (I was told by the Mercedes CS guy that it is supposed to trickle out.. another misstatement)

I reached down with a long screwdriver and carefully pulled the flap open and a sizable chunk of wet organic debris came out and the water started flowing freely. It was as simple as that. I put the car back together and ran it through the car wash with my fingers crossed and not a drop came into the car.

I simply can't believe that the folks at MBZ didn't tell me about the nozzle and the flap and that from time to time it can get clogged... even if it doesn't show at the top of the drain. It seemed to me that they were more interested in getting me into a dealership to have it looked at as if I wanted to spend a few hundred dollars doing some unnecessary repairs when it was a 10 minute fix.

In total the repair took me two days to find (working a little each day since it was in the single digits outside and not that much warmer in the garage) and but a moment to fix once discovered.

Props to me and shame on Mercedes. Hope this helps save someone else from an equally frustrating time.
the flap, at the end of that pathetic, short tube.
yes, same thing happened to me earlier this year.
half the car, carpet actually, was filled with water 3 inches deep.

so that flap was chopped off for good. no more worries of it getting stuck shut.

(Pics of RHD cars, mine)
 

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1995 C280 (165K mi)
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1,595 Posts
I never knew of this flap. I can't seem to find this in my car. Mine has a drain on either side of the hood next to the firewall that runs down.

Does you guys' drain into the engine bay? From the looks of this it may.
 

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9 Posts
Had the same issue. When I was replacing my wiper motor today I did notice the drain was plugged with pine needles. Easy fix. Good post! :)
 

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1999 C280, 2015 C300
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384 Posts
I did not know that Mercedes factory is still available to help and answer questions when the car is so old and out warranty.
 
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