Hi Folks, this feels like a silly question but I don't know how the electric sunroof in my 87 300D is supposed to work.

Starting with the sunroof all the way open, I'll push the button forward to close it. It will come forward nicely and close and continue directly into the tilted open position. The same is true in reverse, I can close it from the tilted open position and it continues directly into the fully open position.

The owners manual doesn't really spell out how this should work, but what I'd expect is that the sunroof should stop when it's fully closed, and then if I push the switch again, continue into the tilt. Currently, I have to have good timing to get it closed right - which is fine but feels wrong.

If it's supposed to stop on it's own but doesn't, what could be wrong?

All the best,
Ben.

With the sunroof closed, pushing up on the rear of the switch pops the sunroof up and pulling down returns it to the closed position. It sounds like you are doing both the "open" and "pop up" switch moves simultaneously.

Thanks Jeremy! I did not realize that the switch had two different operations: Up and down and forward and backward.

I just ran down and played with the sunroof some more.

With the sunroof closed, I slide the switch backwards and the sunroof opens all the way. Slide the switch forwards, and it closes and then pops the sunroof up.

From this position, pulling down does nothing, but sliding back closes the 'popped up' sunroof and then slides it back to being wide open.


What it sounds like you're saying is that the sliding movement of the switch should only control the full opening and closing of the sunroof, and the switch moving up and down should only control the "pop up".

This is great. Thanks so much. Something must be wired wrong?

Ben.

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'79 300TD, '87 300D

Simply sliding the switch all the way forward or backwards opens and closes the sunroof. Pushing the button UP or DOWN makes the vent go up or down.

Don't forget to maintain your sunroof or you could end up with some very nasty surprises.

1) Make sure the rails that it runs on are clean. Simply open your car door and stand on the door threshold with it all the way open and clean that track well.

2) Use the MB very thin grease to lube the track with. The grease is VERY expensive, so you might have to find a thin substitute.

3) Lube the up/down mechanism that pops up the little flap and make sure all that stuff is clean otherwise your sunroof won't work right. I suspect that is part of your problem if it's opening the vent upward when closed.

4) Take a look at your seal. If it's getting old, you can try some Prestone power steering fluid with Stop Leak on the seal. Just apply and let it soak in, then wipe off. That stuff does miracles to rejuvenate rubber.

It sounds from your description, Ben, that the switch may be partly broken internally. If you do end up replacing the switch, try to get the later version (introduced about 1988) that is illuminated. You should be able to get a used one from a junkyard; I'm sure new ones are expensive.

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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

It sounds like the sunroof was serviced (cable cleaned/lubed/replaced) without the limit switches being properly adjusted after.

I will need to remember how the drive is disengaged, but IIRC you need to run the sunroof to the completely closed position (there is a point where the sunroof is up and locked, but not yet opening), then disengage the drive (I believe that you pull the white knob out on the drive unit in your trunk), run the switch forward until the motor stops running (which indicates that it has turned off via the limit switch), then re-engage drive and try to operate normally.

This is not the factory method, but I have found that this works well and is much easier than the factory method after servicing the cable. I'm not completely sure on the details (knob / disengaging) as it has been a few years, but it sounds right.

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Gone to the dark side

- Jeff

As mbach noted, the factory grease is expensive and comes in a large quantity suitable for 100 years use by an individual. Instead, buy a small quantity of factory grease from the business that supports this forum. The factory grease won't be washed off by water and won't attract dust.

Thank you guys, this is all great advice. I'll try recalibrating the drive as Jeff suggested. I read about the factory method but this sounds like it would work well.

I have been dreaming about getting everything in that sunroof cleaned up and lubricated, so it sounds like now is my chance.

Thanks again!

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'79 300TD, '87 300D