Anyone replace a window motor in a w126?
 

I decided to troubleshoot the windows on my 1982 300SD, three of which don't work. I tested all of the switches in the console with the remaining good window and they all work as they should. Then, I took the driver's door panel off and tested the leads to the window motor. Again, it checked out fine (12V on each lead, each grounds when switch activated) which narrows it down to the motor itself. Now, I checked the FSM and it states that removal requires one to roll down the window. Call me crazy, but you probably wouldn't be taking out the regulator or motor if the window worked :rolleyes:...anyway I was wondering if anyone had taken out the motor with the window up? Does it need to be taken out as an assembly with the regulator (looked that way, and FSM specified it), or can I somehow just take the motor out and replace? Anyone rebuilt one of these?

TYIA, TC

What they are saying is that the motor and the sliding arm come out easier if you let the window drop into the door. It has been a while since I have had a window motor out but do not remember it as a big deal. Never tried to rebuild one but MB in those days built things to be repaired. Basically a mechanic's dream. So I would give it a try. What can it hurt?

I removed both of my rear ones on a 123 so it could be different.
The FSM als said to remove the Rail from the window with the window in the down position. It said to push the window to the top and support it in the up position with a stick. In my case I shoved the window up and used that wide Clear Packing Tape stuck on the outside of the Window and looped over the top Door Frame and stuck to the inside of the Window times 3 per each window.

When I tested the Window motors I took apart the wire connector that the switch plugs into (there is no Terminal Block where the wires screw into on my car). When I did this the Motors would not work.

With only the 2 wires that go to the Motor what I found is that it did not work as I thought it did.

I thought that I only needed top apply (+) current to 1 wire at a time and the Motor would be grounded through the Chassie.
What I had to do was put (+) to one wire and (-, or ground the other wire) and the motor would turn one way and swapping them the motor would turn the other way.

I also found that Both of the Window Regulator Mounting plates were bent and that the Regulator Arms on both had Rounded Gear Teeth due to not running in proper alinment. The motors themselve seem to work fine.

Also on mine the motor is held in by 3 bolts with 10mm heads (in the rear Windows). It might be possible to squeeze your hands in with a 10mm Combination or Box wrench and remove the Motor leaving the Regulator Rail assy in place. Becareful the Regulator Arm is spring loaded; when you pull the Motor the spring will act on the arm.

When you start undoing some bolts and screws to take the motor out the window will start to sag. If you take enough of them out the window will come all the way down. I think this is why they FSM states to put the window down. It is not a big deal.

I took the front passenger side out when the window was stuck up on my SD. The motor was stuck. I took it apart and relubed everything I could. Put it back together and it has been working for over a year.

How the heck fire do you properly reattach the white plastic bushing that holds the regulator arm to the window channel? Someone must have posted a DIY on this somewhere but I have yet to find it through the search.

When I did this on my car the first time I removed the two screws that hold the motor to the gear head and then I could rotate the motor and unscrew it from the head. Doing this left all the hardware in place so I just had the motor out. Look at the attached pictures and you can see how it comes apart. After I got the motor out I was able to take it apart and clean and re lube everthing and just screw it back and it has worked ever since.

Thank you for the detailed responses! I'll try and separate the motor tonight, take some pictures, and report back. My best guess is the motor being all gummed up--the remaining working window (and sunroof) is slowwww. Would anyone recommend using electronics cleaner on it? If not, I'll just use lightweight oil and probably lithium grease to lube. Thanks! -TC

That first one that I took out had one of the bushings frozen on the shaft and it took some work to get it apart but then I lubed with lithium grease and it's still working.

The white plastic "jaw" slides into the channel and will stay in the limits of the channel when it's all put back together properly. If your asking how the jaw attaches to the regulator then yours is broken. It is held in with a rivet.

It really can be quite a PITA to mess with the regulator. Once you do one you should have a good idea how to do it quickly. The motor/regulator assembly can come out of the door just as fast as it takes to remove the door panel.

Don't go overboard with the grease or your car will smell like grease for quite a while. I think mine still may smells like grease.

Little dab will do ya on the greeze. So I have to remove the regulator and I assume when you reinstall it, you can get the jaw back into the channel without issue?

With the regulator out, do you attach the jaw with blunt force? How do you keep from crushing the plastic part? That is the main reason I did not remove the regulator last time, I didn't see how I could attach it any more effectively out of the car. You have to admit its a poorly thought out piece.

Sliding Jaw
 

Do a search on Sliding jaw. lot of info there.
I have one to do one of these days also :(.

Charlie

Fixing window is not as difficult as one may think. You have 4 doors, 2 driver side and 2 passenger side. If you are stuck, look at the other 'working' door. The pain is to remove the panel to look at the good one but MBZ panel is not difficult to remove, a pre-requisite for all MBZ lovers.

Problem with windows:

1) A lot of the time it is the teeth is gone and you are screwed.
2) Or may be motor brushes - possible to replace. I have cut other carbon brushes to size before.
3) gear reduction worn out - screwed.
4) Plastic attachment broke - screwed
5) Frame bent - possible fix
6) May be electric then you are in luck - trace the wires. It is only 2 wires and it change polarity for going up/down. It is NOT connected to chassis.

Look at what is broken and if you think you can fix it then attempt to do it, otherwise get one from a junk yard or buy new.

Good luck.

Update: I spent the night with my window motor. It took me a while to figure out how to get it out (after realizing a small mirror was essential). I pulled the motor and took it apart. The commutator was completely seized up, the large gear off the worm gear was almost seized. I soaked the friction points in liquid wrench for about an hour, and they broke free. After another 15 minutes of wiggling and manually turning the commutator, I was able to get it acceptably smooth. I sprayed lithium grease on the moving parts, and electronics cleaner on all of the connections. I popped it back in and voila! a power window!

The only mistake I made was prying off the back metal cover on the motor. Apparently it was riveted on and shouldn't have come off. There's a plastic retainer holding in the commutator after the worm gear that now rattles because it is not held in place. I'm planning on drilling and tapping the rivets, replacing them with screws. I'll upload some pictures tomorrow, but right now I have to wake up and go to work in 5 hours :(

Thanks for all the advice!!

good job. I pulled that cover off of two motors in order to check/refill the grease. I think you can get away with gluing it on with RTV or something. Just something to keep the water out and dirt out. My drivers door motor seems to always get wet.:rolleyes:

I did the same thing. :)

I just used a fair amount of electrical tape to hold it tightly in place. It has held for over a year.

Good job.