My 1987 300D Turbo (W124, OM603) is currently at the local dealer for exactly that problem. They completely rebuilt the sunroof last September using all the latest upgraded parts.

I use the pop-up feature a lot but rarely slide the sunroof open. A week ago, in cleaning the car, I decided to open the sunroof and found that it would move only an inch or two and then stall. I immediately closed the sunroof (the tilt still worked, BTW) and took the car back to the dealer.

They found that some of the new parts had broken (the cast pot-metal track pieces) and are replacing them on warranty. So far, they have not been able to find a cause. The sunroof motor has never been replaced and they are not eager to do so since it would cost me over $400 plus labor. However, they can't find anything else to point to.

At the moment, I'm waiting to get the car back (they even gave me a loaner for the weekend, a 2009 C350). The service manager's advice of last Friday was "don't use the sliding part of the sunroof, since we can't figure out what is causing the parts to break."

I pass on this tale for the information of others and also to ask if anyone has had a similar problem that was eventually traced to the motor or clutch.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970