During the final prep for paint, I had noticed a little rust bubble appearing on the outside lower edge of the rear side wind seal and chose to investigate by removing the window and seal....what I found, was about 9 inches of window seal channel gone, rusted through, crud!


Arrg, this showed no signs either on the interior as it was hidden by the wheel arch carpet panel, but on disassembly and grinding, I was shocked at how much rust there was. Apparently, water has been getting into the channel for some time, although the seal was gooped in the MB non hardening glaze, both in the seal channel as well as the window/glass channel, all of that was not enough to keep the water at bay.


Currently, I have cut out the rusted areas, and started fabbing patch panels to commence the repair. I will be zinc treating the area well, and overlaying a 2k epoxy primer over the entire area when finished welding in the patches.

Note of caution to wagon, owners, inspect your rear window seals really closely and look for any signs of rust, as you will probably have some hiding, better to address sooner rather than later if the car is a keeper.

QUESTIONS:
I'm surprised that MB chose to use the glazing between the body and the seal, vs rubber trim adhesive/sealant. I understand the use of the glazing in the window glass channel, but not so much on the seal to body joint. For those of you who have done this type of repair, did you continue with the glazing as MB did, or did you opt for rubber seal adhesive instead? I wondering if the adhesive would be the better option to really affix the seal to the bodywork and forego future water penetration as occurred with the glaze?

Thanks,

Some pics below of the damage and patch panel fitting thusfar

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)

Anywho To those W124 wagon owners who will likely encounter rear side window rust in the future, this is a follow up to wrap up details from my experience in the hope that they are useful to others.

Maybe this belongs in the Tech Help Section as there are many more gasser wagons than diesels. Moderator please feel free to move as appropriate.

Some picture below will show my progress from welding in the patches, finishing and back to like it never even happened.

To Answer my own question about the non-hardening glaze. It's a MUST. I hate to say this, but MB's design for this window seal is pretty poor, actually very bad, having only 3 objectives as a seal to seal the body from moisture entry, to seal the window from moisture entry and to well, hold the window.

The MB seal does 1 of these really well...hold the window, moisture entry....not so much, even the FSM details the need of glazing in both the body to seal surface and the seal to glass surface, which leads one to ask, what the heck does the pliable rubber seal do??? Oh yeah, hold in the glass.

The seal itself is easy to install and from both the FSM and my experience needs to be fitted to the body before installing the glass. Fitting the glass requires some fidgeting to shift the glass to the lower rear corner in the process of roping the seal from the lower rear corner up to the upper from corner of the glass. Helping hands are a big plus, but doable solo.

The metal seal trim plate is a bear to install. The FSM says to start from the rearmost side and work towards the front. I tried this for 45 min unsuccessfully. It may require two people to do it this way because you need to maintain perfect stability, alignment and simultaneously hammer (mallet) the seal into the channel.

I chose instead to start at the front most edge and work rearwards as the front edge is held by tangs and is aligned and therefore you only need to use a rubber mallet to progressively work the trim into the channel. This way took 10 min. but hey, I'm neither unionized nor paid by the hour, so pick the method that works best for you.

Everything is fairly straight forward in this job, no real special concerns. Hope this helps.

Attached Thumbnails

       

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)

Right on! Nice looking, solid repair.

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- Greg -
1973 220D, The Prodigal Benz
1974 240D

You say "non hardening glaze"...what exactly is this stuff? Do you have a link to a product?

Non-hardening window glaze, is a joint compound used between the body and seal as well as the seal and window glass. It is a caulk like product that does not fully dry/harden allowing there to be flex for body flex as well as temperature expansion without breaking the "seal" of the joint. It is imperative to use this glaze on the rear side windows to also accommodate the various gaps.

You can get it from Mercedes, expensive and I dont know the part# for that or use a 3M substitute as I did

https://www.3m.com/3M/en_US/p/d/b40067023/

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)

Great work and great documentation and notes.

Probably need to check sooner than later!

:-) neil

One of the mods here told me to use plumber's putty. I had no leaks but just needed to replace delaminated rear glass. I did find a bit of rust so I'm going to strip the lower channel when I remove the rear glass to paint, Lord willing.

Imo, the design on the rear windshield, seal and sheet metal is exceptional. I doubt the manufacturers expected us to go nuts and keep these cars running for half a century.

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84 300SD
85 380SE
83 528e
95 318ic

So glad I found this thread, as I am about to tackle the same job on my 95 wagon, which has pretty similar damage. A nasty little “snap,” accompanied by a foot-long crack, was the result of my last effort, decades ago, to remove a windshield from a Corvair. I think maybe a screwdriver wasn’t the right tool.

I have removed all the faded, multi-colored lower body cladding and the bumpers, which I am painting Polar White to match the top. I was never a fan of the silver lower panels. Fight me.

Share some before & after pics please.

I'm also not a fan of the two-tone paint & lower-cladding. Love my all-black S124 . . .

:-) neil