There is rubber on the roof around the sunroof panel.
It is on the roof body, not on the moving panel of the sunroof.

Is it glued on the roof?

Or is it inserted into a gap in the roof?

If you removed and reinstalled this rubber, please give me some advise. Thanks.

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I just did this on a 126 and the part you posted a picture of looks exactly the same. Assuming it is, you "just" press it in with no adhesive. Get some spray silicone or use some soapy water to make it go in easier. It's very fiddly. It took me a half hour or so to get it all the way in...because of the shape, you have to manipulate it quite a bit.

There's a bottom edge that nees to fit in a channel like this -> ]
The idea is to get the bottom in the channel without letting it slip below it - then you have to force the top edge in until it all fits in the groove tightly. It will become more apparent with time...

As for removal, just pull it out. You may need a pair of vicegrips to get it out, but take a moment to note how the seal is oriented. Mine deteriorated further while removing it and I had to clean up the channel a bit to get it all out.

Good luck

__________________
Joel
1985 300td (sold)
1981 280SEL (4-speed)

Thank you.

I thought I need to place the rubber and then drill rivets to fasten a hoding rail.

Did you find rust after you removed the rubber?


===================

Sun roof
open, do not remove

Installation position of gasket
mark on roof cutout at joins (arrows)

Gasket (1)
pull out of holding rails 2, 3, 4 and 5

Wind deflector
remove and install. See: Sunroof Windguard\Service and Repair

Screw (6)
unscrew 6 ea., screw in

Holding rail (2)
remove and install (refer to installation note )

Screw (7) and (8)
unscrew 8 ea., screw in

Holding rails (3) and (4)
push toward the rear and remove in upward direction.

Holding rail (5)
can be removed and installed only upon removal of sun roof frame and drilling out of rivets (11 each)

Gasket (9)
push into holding rails 2, 3, 4 and 5. The serrations on plug-in profile should point in upward direction.

Installation Note :
To make sure that the gasket (1) obtains an adequate hold in holding rails 2, 3 and 4, a gap dimension of 3 mm between holding rail and roof panelling should be maintained.

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That looks like much more work than on the 123 and 126 cars, but perhaps it's because there is no side felt? If t appears that the front seal wraps around the side on the 124 cars. Sorry to mislead you in my assumption they were similar.

Looking at the instructions and drawing, I'd sure as hell try to avoid having to drop the pan and drill out the rivets. Removing everything else appears pretty straightforward and may provide you with the room to work without pulling that rear piece.

As for rust, yes, I had some. The seals were completely dried out when I got the car so there was some serious leakage. There didn't appear to be much in the sunroof seal channel, though. I touched up with POR-15 as best I could without dropping the sunroof pan assembly.

__________________
Joel
1985 300td (sold)
1981 280SEL (4-speed)

Thank you for your reply.

I did not see the 126 sunroof, but I saw 123 sunroof. The sides had felt.
But in 124, sides are also rubber.

I touched up a rust area with POR-15 where the rubber meet the roof body. And then applied white MB touch up stick above POR-15 coating. It was a few months ago.

The area with MB touch up paint makes me worry.
The area that faces the sky looks OK. But the small area that faces the rubber has dark dots because the white touch up paint was removed partially.
I hope it is not due to rust growing beneath the POR-15 coating.