Still working on the mystery sunroof problem - removed the plastic nut that is used to manualy close the roof - there is a metal 17 mm thin bolt under it that is striped. Should this bolt be tight? Is it perhaps to do with the clutch? Because of all my lubricating manualy from the trunk the roof opens and closes quite easily. Electricaly the motor just turns. Does anybody know what I'm talking about?
Can anybody tell me what is the thread size of the nut which is behind the plastic nut ? -

i dont know what model u are working on. on my 116 than nut locks the compression washer to the gear to allow the internal gears to move.

that may too be your problem.

dave

It's a 1986 300E - W124 --- Does this bolt need to be tight in order for the motor to engage the gear ?

On my '84 300D beneath the plastic "nut" is a threaded shaft of a gear that drives the cable. There is a 17 mm nut on the gear shaft under the plastic nut. If the 17 mm nut is loose on the gear shaft I don't think the gear will engage the sunroof drive cable.

I agree with hxpa on this issue. If your sunroof open and closes manually, you should be very happy! My cable broke, and I couldn't get it open manually from the trunk, so I decided to open it manually, from the interior. I found broken parts, worn felt gliders and no grease on the tracks. So I have been in the process of rebuilding my sunroof completely, now I'm at the point where I need a new cable to complete this task. I will be posting photos with notes soon, for those of you who know you can fix it if you only knew where to start first.

If the 17mm nut is striped so bad that a 6-point socket won't remove it, you may have to cut into it from one side with a dremel tool or attachment on a drill to open it up, or use a cold chisel and a hammer to unscrew it.

Good luck on it!