I replaced the rear seal in my previous coupe, and I too found that the rubber seemed to age rather quickly. Everything looked good at the beginning, but one of the bottom corners looked a little off after about a year.

I wanted professional help replacing the seal in this car, but Autolite said they would only do the job if it involved replacing the glass - glass they do not stock and can not get.

So,I have the new Mercedes seal here waiting for me to get to work on it. I guess I could have saved some money with an aftermarket seal. Oh well.

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1982 300CD Petrol/Black Leather

Interesting! The 2 used gaskets I have are original from 1985 and 1982 AFAIK. They both have the same p/n embossed on it. When I called the dealer to get a price of a new one, they couldn't find the p/n I gave them (they gave me a new p/n) so it must have been superseded. Maybe they changed supplier also and the new gaskets are inferior? My 2 used gaskets are soft and pliable with no signs of dry rot or cracks. I'll post the p/n of the spare gasket when I get a chance.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Is there any Manufacturers ID other than the Mercedes stuff on the Seal?

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84 300D, 82 Volvo 244Gl Diesel

Or perhaps those seals haven't been baking in the sun on a car windsheild, for a year or two....
It's amazing what U-V rays can do to rubber and plastic in a relatively short time.

In the mid '80s, I knew a lady that had a 1968 British Sunbeam Arrow sedan (AKA Hillman Hunter in the UK) that she had owned since new. The front and rear windsheilds had these silver-metallic trim-strips pressed into the gaskets that looked like aluminum, but were actually clear plastic with aluminum-foil sandwiched inside. The same stuff was used on many imports from the late 60s through the 80s, including Opels and BMWs.
Typically this plastic trim turns brown after several years, but the lady had kept this Sunbeam garaged - up until she decided it was time for a new car. She bought a new POS Pontiac Sunbird which went in her garage, while the Sunbeam wound up sitting outside until she finally decided to sell it.
Within six months all that pristine silver plastic windsheild trim had turned brown!

Happy Motoring, Mark

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DrDKW

Thanks for all the replies guys! This has certainly given me some things to think about. So is the general consensus that it is better to try one of the aftermarket seals vs. the Mercedes seal which may have aged by now? Maybe an aftermarket seal with the Mercedes non-hardening sealant?

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1984 Mercedes-Benz 300D

It has been over 5 years since I have changed one, but I never had any issues with 2 aftermarket rear seals I used.

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

Looks like I may have a buyer for the gasket. The faded part number on it is 123 678 04 20 as far as I can make it out.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

No markings whatsoever, just the tag from the dealer. It looks and feels fresh, though.

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1982 300CD Petrol/Black Leather

Took my 300cd to caruso's auto body in NJ. Theymdid a great job, and used the right sealant in the corners. Was pretty cheap too. Need to take the 240d up there.

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

Mercedes makes a foam tape that is apparently intended to help the window seal. Does anybody know anything about it?

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1982 300CD Petrol/Black Leather