It seems many mercedes owners have a similar problem, but when it rains, it rains on the inside of my 1982 300TD. The problem is that its coming out of the head panel in my interior. When I look at the drain holes from the top of an open sunroof, the hole on the passenger side is so rusted out, its almost hard to see it. I had my mechanic blow out the drains with an air compressor a while back and he said the drivers side was clogged and came clean, but he had a hard time finding the other one due to the rust. My interior is suffering badly due to the leak, and whats worse is that the foot wells of my car now have rust holes all the way through. I'm scared to take the headpanel down to inspect the damage, because I think its very rusted out. I'd like to stop this from continuing and wondered if it were possible to put in some sort of new rubber tubing into the drain lines and sillicone them in?? I'm not really sure how that would work, but i wondered if anyone else had rusted out drains and had successfully dealt with them? Help i'm desperate. I don't want to have to seal up my sunroof, but I don't want my car to rust out!! Lucky for my car, Ohio is in a severe drought right now but I would appreciate any suggestions!!

you can certainly run new rubber hoses as the old ones dry out and crack. I did it on a '79 SD and it was a PITA as I used SAE measure tubing and it was probably a hair too thick so making it come out the other side was an exercise, even with liberal siilcone lube.

For you drains you should be able to remove the sunroof frame and weld on (jb or real metal weld) new drain exits. Though not ideal you'll have to remove the headliner and part of the upper interior trim. I think the later 123's including yours is a bit less of a puzzle than the 79 116 which has an order of assembly that's not obvious.

In any case it will be a chance to to a full overhaul of your sunroof assembly (cable, frame, slide rails, etc.) and maybe discover other lurking rust.

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1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)