Friends, My '09 S550 driver's side door mirror doesn't always fold in upon locking the car or pressing the fold-in button. I noticed it is worse now that the air has turned colder. I read on a couple of older threads on this forum that is may simply be a matter of cleaning the old grease out of the mechanism. So this weekend I removed the mirror assembly, which was quick - pop off the inside speaker tweeter cover, under the foam insulation find the three screws. Pop of the half moon forward edge door cover to unplug the harness assembly. Mirror came right off.
On the bench, I was able to pop off the mirror and begin disassembly with the T10 tool. Removed the old mud-dobber's nest too!? With the large torx drive, I removed the pivot pin with the large spring underneath and that separated the mirror from the pivoting surface. Yep, it was gunky old dirty grease. Cleaned up the two surfaces, used a nice light coating of Sylglide, a NAPA waterproof high temperature grease.
I installed the mirror and it was working like a champ. In - out - in -out, multiple testing. button and locking of car. It was 70F in the shop.
This morning, I drove the car to the office and it is 43F outside. Got to the car park and when I locked the car, the mirror folded about 15 degrees, stopped and I heard the motor run a little more. Now the mirror assembly is not really latched - meaning it has about 5-10 degrees of in/out movement. I tried unlocking, locking a few times and the mirror didn't move.
I attached a couple of pictures while mirror was on the bench.

What's my next move? Is the folding motor's gearing needing cleaning? Not sure how to get into the motor. Is the motor available rather than the entire assembly?

 

I have had a similar problem (MY2008) for more than 5 five years on the left mirror and since a couple of years even on the right side. The left mirror folds/unfolds perfectly about 9 out of 10 tens times nowadays, the right 19 out of 20 times (as an average, but it seems very random). Yes, damp and cold weather seems to make it a little worse, and it seems to slowly get worse over the years.

I discussed this with the official MB workshop a couple of years ago, and they think it could be a broken cable. But I am not convinced. If I move the mirror not folding ever so slightly within a second or so it starts to fold or unfold as it should. That it happens both if it folds or unfolds would not support the broken cable theory, I think?

 

Thanks for the photos, first time I've seen one disassembled! I believe that the part you've cleaned and lubricated is actually the 'break-away' part of the mirror, intended to prevent a pedestrian from being killed too severely if struck by it. The folding motor is likely to have some resistance circuitry or mechanical clutch that will stop if the force required to operate is outside of its specification. So theoretically you could disassemble the folding motor and see what's what in there. Perhaps a similar buildup of crust and critters that if cleaned would return the motor to operation again?

My right side mirror is having a similar issue, so if I beat you to it I'll post pics of what I find.

 

Not sure, So I tried to study the passenger side mirror as it folded in and out. I can barely see the metal edge of the top layer moving, so I do think the motor does pivot the mirror on the breakaway surface? Anybody chime in?
But in my first picture, you can see three more T10 screws having I think to do with the folding motor. I did not take that apart. Doh! I'll try to get it off and examined with further photos this evening.

 

So I removed my driver's side mirror to further disassemble the mirror to dig into the folding mirror part. As I mentioned in the previous post, there are three T10 screws holding the motor in the casing. I removed the motor. The top of the motor has a clipped on cap. Beneath is the motor with a screw drive gear coated with a white color grease. The bottom of the mirror has a large clip on cap and it covers a gearbox assembly coated with a different grease (note the interesting small ball bearing wheel assembly). My grease didn't feel to gummy, however, suspicious that it might be, I cleaned all parts with a grease dissolving brake cleaner spray (on hand) and coated all gearing with the NAPA Sil Glyde waterproof non-gumming grease. Mirror back together and on car. However, the mirror is in some kind of "not open, not folded" state and the mirror will not operate. Thoughts? My next move was to remove the fuses controlling the folding mirrors, of which I think there are 4 or 5 listed on the fuse chart. Some are on the passenger side fuse box and some are in the box in the rear seat. It was supper time so I had to quit. I've attached a bunch of photos for reference. Anybody have any thoughts?

 

Not sure if it will help, but disconnecting and reconnecting the power in the trunk will give you a chance to automatically realign lots of stuff like all windows, folding mirrors, sunroof, etc. during the first full movement.

Regarding the root of the problem: Could it be that the carbon brushes of the motor are worn out and lose contact randomly? Just speculating...

 

Thanks for the ideas. Power in the trunk? Specifically I'm not sure what you are referring there. That was also my line of thinking of pulling each fuse out. What and where in the trunk?

Secondarily, yes, I'm wondering if the little motor is simply worn out. Love to be able to purchase just the motor, but it looks like the bulk of the assembly is what has to be replaced.

 

There is a black cable connected to the chassis with a nut below the floor of the trunk (on the right side). Just lift the floor, disconnect, wait for a couple of minutes and reconnect. Not sure it it helps your particular issue that the mirror doesn't move at all anymore though.

Could be just a cheap generic motor. Might be possible to find it somewhere on the internet for a couple of dollars.

 

If you swap the left and right motors, you could identify if the motor is the root of the problem.

 

KiloWatt - thanks for the ideas. Swapping motors- yes, another idea, but dang I'm getting tired of taking the mirrors apart. But, I know how to do it. I'll let you know what I learn.

 

Awesome photos! So, do you hear the motor running or trying to run when the folding operation is initiated? Perhaps instead of disassembling it again, try connecting a meter to the connector from the car side and see if you're getting any current when you press the fold/unfold button?

 

Also, if you think it is the motor ... this thread seems to identify correctly the motor needed (Mabuchi FC-280);

https://www.slkworld.com/slk-r172-cl...ror-motor.html

Which looks to be available on Amazon for ~$11;


Just wondering if you think you could get the worm drive off the existing motor and onto the new one.

 

Looks pretty similar: https://www.ebay.de/itm/Mabuchi-FC-2...5X~u:rk:4:pf:0

 

While you have all that apart, Id def next day a new motor for under 20 bux u really cant go wrong. Are those gears brass? if not maybe a worn tooth that isnt catching? Id still change that motor while its apart.

 

Friends,
Once again, I took the driver's side mirror apart. With the motor alone in my hand, I gave it a 12v source one way and then the other way and the little motor spun away. I installed it in the gear box and ran it both ways again. Seems to work well. Then assembled the mirror except for wiring up the motor and again gave it 12v forward and backwards. But remember, the last time it was on the car it wasn't either fully open or fully closed. I plugged the wiring harness into the door sockets with the mirror in my hand and hit the close mirror button. Nothing happened. I pulled the three fuses related to the exterior mirrors, left them out for a minute and put them back in. Nothing changed. So I took the mirror back over to my 12v source and ran the motor fully opened, it hits a stop so I immediately removed power. Fully closed it, it hits a stop and I removed power. I fully unfolded the mirror, connected back up the wiring and placed it back on the car. Tested the mirror with the folding button and the lock/unlock system. Mirror is folding nicely.
Drove the car to the office this morning. It is 52F this morning and the mirror folded completely upon locking the car.
While the folding mirror was in my hand, I took a picture and gathered the numbers off the motor:
FC-280ST-16200
VT 428521
Made in Vietnam
On the top it says: Mabuchi Motor
Afterthought - should have put a drop or two of fine oil on the motor shaft to run inside motor.

 

Is there some kind of a contact or sensor that tells the system if it is at one of the stops? Why wouldn't i run if it's plugged in not fully closed or open?

 

My guess is the mechanical stop puts a load on the current to the motor and the car's controller senses the "overload" and stops the current flow to the motor. My mirror is still functioning properly so far. I don't have a guess as to why it didn't run after rebuilding and plugged into the car with the mirror in the middle (neither fully open nor fully closed). There are not limit switches inside the mirror assembly which would tell the controller open or closed.

 

Update: It has been a few days now, cold, rainy weather. Car locked, unlocked, driven quite a bit over the last few days. Mirror still folding normally. I think the new grease in the folding gearbox mechanism as well as new/clean grease on the pivoting surface has been the solution.

 

sweet, cool that u posted this Im sure it will help others.

 

Grateful for your efforts and follow up including the photos! This is not a procedure I've seen documented in any of the WIS information, so to have it so clearly laid out here is YUGE!