sunroof woes
 

I have an '87 420sel with a sunroof that stuck about half open. Instead of checking the fuse (oops, it was raining, I was trying to protect the interior, etc.) I cranked the roof shut manually. Now that I've replaced the fuse, the roof will not operate electrically. I can hear the motor running but nothing moves. I don't believe I cranked it too tight, but with my luck lately, it's a possibility. I have removed the headliner from the sunroof but I can't see a cable or anywhere where one was attached. Does anyone have a diagram or an idea of where I should start? I'm missing some great weather here in VA! Thanks.

John:

The cable is a teleflex (single) cable and it attached at the very rear of the sunroof to a cross piece called the translation bridge.

Usually, when the sunroof sticks, it's becuase one or both of the lift angles are broken and dragging.

You have the headliner out, so take a look at the translation bridge -- it must be square to the roof panel. If not, one of the lift angles is broken. I don't believe the motor will move the sunroof with a broken lift angle, the torque is too high and the motor will slip. You can reef down on the manual nut and move it, but if you crank it far enough for the rear to lift, you may jam it.

Take a look at the mechanism on the sides -- if there are no broken bits (usually obvious), it just needs lubricated. Get some sunroof paste (Rusty at *************** sells a 2 ox tin for $5.00 -- the standard size is a quart can for about &70) and open the roof and lube all the sliding surfaces and pads. This will usually fix a slow or binding sunroof.

Please, please DO NOT use anything else -- the MB paste is essentially a dry lubricant. Anything that stays greasy will collect dirt, and you will be worse off than before.

If one of the lift angles is broken, you will need to remove the top panel and replace BOTH lift angles (about $95 each when I did mine about 2.5 years ago). The originals are rather light, and fracture at the hinge.

Details for repair have been posted before, do a search or respond & I'll type them again.

Peter

Thanks for the thoughtful reply. I have inspected the rails and can't find any evidence of broken parts. The lifts are in good condition. The roof worked fine and did not bind until the day it quit, so I'm hoping lubrication will solve the problem. I just hope I didn't strip out anything by cranking it shut.

John:

The sunroof motor has a torque clutch -- it slips fully open or fully up -- so you haven't done anything.

You may have to re-adjust the clutch to get it to work properly after lubing it if it is slipping at too low a torque.

If you'd damaged the cable or motor gearing, it wouldn't have closed manually.

Peter

How about this one?
1995 E320 wag steel tilt / slide roof.
Worked perfectly for some time, silent operation. Then I opened it and it went down to clear the roofline and stopped. One corner had made it slightly further back than the other, so I gave it a little push and it went all the way back. It would always close, and will always tilt up. Now, it seems to always open but there is jamming sound just after the point when it drops down and begins to slide backward, like it is binding for just a second. This is what it currently does, and as before, has no problem closing or tilting. By the way, when it wouldn't open at all (when it went down to clear the roof but would not go back further, I could hear the motor in the rear on but nothing moved.) I have owned since 39k and it has never had this problem; I have never used the manual feature.

Lubricate properly and check for a broken lift angle.

Peter

Peter, how is the clutch adjusted? I purchased a 190E recently and the sunroof does not work at all. The motor spins when the switch is activated but no movement. Thaks.

If I remember correctly, you remove the plastic nut for the manual crank and loosen the locknut, then turn the screw in to tighten and out to loosen, then reset the nut.

However, you must first verify that the cable is OK -- they do come adrift from the translation bridge and flop around up there, or break.

Best way to check is to see if you can move the sunroof with the manual crank (aka manual wrench -- see your owner's manual for details!). If it moves then, likely the clutch is bad or the gear is sheared. If not, the cable is bad or loose.

Usually you can hear the loose cable crawling around.

Peter

Thanks, Peter. I'll check the manual operation. There is no cable noise when the motor spins. It sounds very smooth and quiet. Tough to get at though. I'm having a problem removing the plastic trunk side panel gracefully.