Before I get roasted I have searched far and wide on every Merc forum I can find for this answer. There are some threads with the same issue but none that provide any solutions.

The isssue. After a series of heavy rains I found the passenger side rear carpet on my newly acquired ‘92 500SL thoroughly soaked. The wetness was from the rear bulkhead forward to the rear edge of the electronics mounted under the seat. The car was parked slightly nose down with the soft top in place.

What I’ve learned so far. There is a drain toward the front of the tonneau. It is Y shaped and can be viewed by lifting the spring loaded latch cover. Water collected by these drains then pass through a hole at the bottom of that compartment and into the funnel attached to the main top lift cylinder. There is a tube attached to the funnel that enters into the body of the car below the main lift cylinder attachment bolt. If I pour water into this drain on the driver side it will run out the back of the rocker in front of the rear tire. If I do the same on the passenger side nothing drips out of the car, instead collecting in that rear ‘footwell’.

I have taken out the rear panels as you would to change that main cylinder and tested the funnel drain for any kind of blockage. It is not blocked. It’s very hard to see where the drain tube goes, so I removed the hydraulic cylinder mounting bolt on the bottom so I could push the cylinder out of the way. I pulled the drain tube and it does route toward the center of the chassis. I tried to to see if I could find a path toward the outside of the car but it seems to only want to go in the opposite direction.

Thoughts? I can’t be the only one to have run up against this.

Because everybody likes pics;
This is where the water enters, you can see a darker line along the bottom of the bulkhead where it’s been wet.



This is the drain tube in question, running into the chassis.




And just because, this is the beauty I’m trying to keep from having disgusting moldy carpets.

 

Bummer, not a very active forum I guess. Anyway, here’s what I figured out in case anyone else searches and come up with all the dead end threads I found.

My main lift cylinder funnel drain tube was run incorrectly through the bottom mounting point of the cylinder. It should be routed through a hole in the side of that compartment that exits into the lower sill or rocker cover. I forgot to take a pic of that correct exit point but you can see it here in this screen capture from an AMG body kit install video.




I had to insert the tube from the hole in the rocker and feed it upwards to grab it in that cavity and pull it into the interior of the car and connect it to the funnel. That requires removing the side sill, which requires pulling the three lower body cladding panels and the sill plate and interior sill covers.

You could try feeding the drain tube from inside the car without all the other disassembly, but I couldn’t get the tube all the way through from the top. It might still drain properly without that tube extending out into the rocker but I already had all the panels pulled.

Im guessing this was all the result of a previous owner pulling the top cylinder out with the funnel and drain attached and not knowing where it went during replacement. Takeaway pro tip; Before pulling out that main lift cylinder, remove the drain tube from the funnel so you don’t have the huge additional hassle of removing all the exterior lower trim from the car to get it back in place.

Correct drain tube routing

 

Good thing you caught it.

Imagine if instead of water it was power top fluid.

Great photos.

I've had my rocker sills off in the past, but I don't remember that hose. I would have suggested seeing if the hose was clogged with debris or something, but yours was a routing issue. Nice job.

 

hi did you find the cause of this as I have the same problem on my1991 500sl also blue black

 

Did you like the original poster's findings?