After a huge rain this weekend I noticed a wet passenger floor. I can see water in my air box and assume the drain is clogged. Is there any way to clear the clog with out taking off the airbox.
Does any one know where the drain is located in the bottom of the airbox?

 

This is a bad design, which Mercedes considered bad enough to have a small emergency drain with flap to be installed in the airbox in case it fills with water and floods the electrics! Your car should have had it done at the dealers ( for free) Poke a length of wire through the box grill and clear some of the rubbish from the bottom to allow it to soak away. Mine flooded and soaked the electics and almost caused me to have an accident when evrything died on me at 70 mph !

Here you go, all you need to know , http://forums.mercedesclub.org.uk/sh...74&postcount=6

http://forums.mercedesclub.org.uk/at...4&d=1182019953

http://forums.mercedesclub.org.uk/at...5&d=1182023708

 

There is large plastic waffle grille located at the top of the engine compartment by the wipers



it covers a reservoir and "funnel" hole that gets clogged with debris and water collects, this water can then leak into your passenger compartment and cause thousands in electrical Damage

Either get a very long thin screwdriver or similar object like a chopstick down through the plastic waffle grille , and clear the drain hole at the bottom of the plastic reservoir

All the water should dump out under your car

I simply broke the tabs off the waffle grille and used my finger to clear the drain hole- water was pouring in my passenger footwell causing Damage

 

Thanks, I found the airbox drain and it was covered. Used a hanger to open the drain and ran plenty of water to flush the drain.
I believe I have been lucky in that is seems no water damage has been done.

 

Good to hear, I had the same problem but my insurance company covered the $2200 bill that caused computer failure

 

This is why this forum is great. You can always find some useful info. I haven't been here in a while but just faced the same problem on my 2003 S500. I initially noticed a damp scent and traced it to wet passenger side floor carpet. It happened after rain, then it dried out and I couldn't figure out where the water came from. Then yesterday took it to car wash and to my horror I had a small water fall in the passenger side foot well. Water eventually drained out, I pulled the carpet off a little and removed the styro foam wall but nothing can be really seen there. No specific damage altough I noticed that the heater is not really blowing very hot anymore. AC still cools. No other electrical issues yet.

When using the wire to clear the air intake did you visibly see some blockage? Just looking down into the air box I don't see any blockage or leaves but the water was sitting there last night until it drained.

 

found much more info here. https://mbworld.org/forums/s-class-w...ins-clean.html

hope this will not turn into more problems.

 

no i couldnt see anything blocking, but if you remove the waffle grille and stick your finger through the drain hole as I did, you could definitely feel the mud and blockage. NO WATER should be sitting there, it should drain immediately so your drain is definitely blocked if you see standing water

that water WILL come into your passenger compartment and cause thousands in damage

Either remove the waffle grille carefully or just break off like I did and stick your finger in there to clear the drain hole

Like you, my heater is now damaged. Still deciding whether to file a comprehensive insurance claim

 

Yes, the whole was plugged, once cleared more water came out and drained off completely. Looks like my heater came back to life also.

 

After clearing the dirt out of the hole on plastic "bowl" the left hand side I discovered a stash of leaves and dirt on the right hand side. They were cunningly hidden and not obvious at all.

Maybe I just did not read this thread properly and maybe it was posted before. Anyway, please check there too. I enclose 2 pictures.

1. The overview so you can find the close-up
2. Close-up with the plastic flap lifted - showing the rubbish inside