I bought a 08 450 GL 6 months ago and had no serious issues until one mont ago the computer systems went haywire. Took it to MB dealer and they found the areas under drivers seat full of water. It appeared the water had been there for some time based on rust on th surface at the top of water line. Dealer says it's $11,000 to replace modules , wiring harness , other components damaged by water. They have no opinion how the water got there. I did leave the sunroof open overnight 3 months ago during a rain storm but can't imagine that caused this much water to accumulate there. Carpets were wet but not flooded as were seats. Any one with similar problem I would like to talk to.

 

water got there because your front sunroof drains are clogged. the truck must have lived outside under trees in its previous life time. water runs along in the a-pillar drain hoses, but since they are clogged (most likely at the bottom dumps behind the front wheels) overflows and leaks into the front foot wells - precisely as shown on your photos.

i am not sure what your options are besides cleaning the drains and taking it in the chin for the electronics repair. alternatively, first i would dry everything in there (pump water out, put inside a dehumifier, close all doors and windows and let it run for 48 hours) and see if things get better.

good luck.

 

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Ive checked the sunroof and air filter drains and they seem to work well now , suppose they may have been clogged in the past but no way to prove if water was there 6 months ago when Purchased, frustrating since Dealer says the problems would have shown sooner if water was there when purchased, who knows?

 

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Ive checked the sunroof and air filter drains and they seem to work well now , suppose they may have been clogged in the past but no way to prove if water was there 6 months ago when Purchased, frustrating since Dealer says the problems would have shown sooner if water was there when purchased, who knows?

 

Scott I know somebody else that did this his ML as well. He left his roof open as well and it got soaked.

I am with alx of course remove all the water, dehumidifier, and then take contact cleaner on all the connectors, and apply dielectric grease. As far as the components you got water logged they also need to be removed and dried you may even have to open them to get all the moisture out.
The reason your bill is probably so high is because cost of components from Mercedes you maybe able to find most of those in a salvage yard.
Good luck with it all

 

that doesnt mean anything. they might have been cleaned in a rough manner and now are leaking both ways (on the ground and in the footwell).

get two identical cups. put one under the drain discharge (or wherever the water comes out under the front wheels). fill the other cup with water. open moonroof, find driver side drain area and pour slowly water in there. check and see if same amount collects in cup on the ground. the difference (if any) went in the footwell. if this is observed a disassembly is required to find the source of the leak.