Sunroof failure

[Henn28]

Well, it’s taken almost 35 years of BMW ownership, but I had my first sunroof failure today. I’ve been chasing rear pax floor leaks and spent some time today (after replacing both horns) troubleshooting.

I was pretty confident I had leaky vapor barriers in the back doors, but also couldn’t get water out of the rear drain holes. I think it’s just because the water runs forward, given the stance of the car and my driveway has a slight slope, but when I went to confirm this with more water, I opened the top, it went back an inch or two and froze.

Fuse 58 is good, and I hear a slight click when I touch the switch (relay?) but no movement at all. Not even an attempt to move. Fortunately I was able to close it with an allen wrench, so my question is how best to troubleshoot the thing? I suspect the motor gave out, but those aren’t cheap and I’d like to be sure before I buy one. Do I need to pull it out to test it?

Also, the guide rails are pretty inexpensive, so are these worth changing out? Do the old ones start binding? I felt like I was on top of lubricating it, so I suspect 24 year old plastic did me in again.

Thanks all.

[Henn28]

I dropped the center trim piece from the headliner today to get to the motor and switch so I could troubleshoot.





When disengaged from the sunroof the motor would turn one direction, but not the other so clearly my issue was either a bad switch or a bad motor/transmission unit. Since I get nothing when the motor was installed, I suspected it, or the gears. Fortunately the cover comes off the drive gear easily and revealed the problem. A broken plastic gear.


New one on order.

[80stech]

Good work, sometimes you just got go at it!

[Henn28]

I’m happy it’s not the rails, or something more difficult to fix. I’ve been ignoring it for a while now. I’ll get the new motor in and do a good visual inspection, and get some grease on the appropriate parts.

Interesting fact that I didn’t know: at least on the non-panoramic version the motor needs to be installed to operate the sunroof via an allen wrench. The center hub of the motor gear is keyed for the wrench, not the sunroof itself. The problem I see with this is there is no way to troubleshoot the roof independently of the motor and transmission.

[X5chemist]

Are carbon gears available? Carbon gears are available for transfer case motors.

What's the part number? Maybe as preventative maintenance, I'll swap mine out.

[Henn28]

I don’t think so, but perhaps. The plastic gear looks like it’s pressed onto the hub with the Allen keyed center. Maybe glued? It’s actually really easy to get to and swap out, so I’m not sure I’d change it out before it fails. I would have either the factory speed wrench (can’t find mine), or an Allen wrench handy in your glove box. I’ll post the size when my new motor arrives.

I did see that the factory tool is still available so I may pick one up. It’s much easier to use than a standard allen wrench as it has a big offset to it…like a speed handle.

[g300d]

Thanks for documenting this!

I did some PM work disabling the tilt on the 3.0 pano roof many many years ago thanks to info here.

I've not come across problems with the smaller sunroofs so good to know beforehand.