1981 300D w123 Drivers side rear window wont go up - PeachParts Mercedes-Benz Forum

drskipper · #1 09-28-2007, 04:11 PM

Hey There. I've had my car off the road for a month or so, because I've been doing some repairs. I changed the wheel bearings,brake discs and pads and got it to start up again. (gunked up N.S.S). Now I have one repair left to get me on the road again and that is ;
My rear driver side window will not go up, I have changed the window switch with the other one to see if thats the problem but still no go, so I took the door panel off and now I'm not sure what to do, I see the window but I cant lift it, do I need to unscrew something?, I am just trying to get it to the up position and leave it there.

Any help would be greatly appreciated, I will take some pictures in a while to make it easier to see what I mean.
Thanks, Martin.

TX76513 · #2 09-28-2007, 04:34 PM

Martin - see the connector block in the lower RH corner of the door - check continuity between that end of the wires and the connector ends at the switch. It's common to have a broken wire in the door tunnel.

tangofox007 · #3 09-28-2007, 04:39 PM

Most likely the "up" wire is broken where it flexes when the door is opened/closed. You can get the window up by removing the door switch and jumpering power from the "down" wire (coming from the console switch) to the "up" wire going to the motor; jump the "down" wire from the motor to ground at the same time.

I have the wiring diagram for the '82. Wire colors might not be the same, however.

toomany MBZ · #4 09-28-2007, 06:01 PM

Check the fuse also.

drskipper · #5 09-30-2007, 03:32 PM

Hey there I am not sure where the connector block is on the bottom right I see no wires but I can feel them behind a hole, is there a way to get off that sheet metal infront or do I need to work around it? also something weird is I found a piece of loose metal in the inside slightly above the bottom right hole. I have pics at this link, http://www.peachparts.com/shopforum/vbpicgallery.php?do=view&g=1486
Thanks in advance again you guys are great!!!!

Richard Eldridge · #6 09-30-2007, 04:00 PM

The piece of loose metal looks to me like the broken end of the door check strap.

Most electric motors can be lubed and coaxed back into spinning. The hard part is that yours is probably soldered in. You c an fiddle with it once it is out by making a pair of test leads out of a nice long piece of 2-wire electrical wire and four alligator clips. These you hook to the battery to test the motor. If the armature is not burned and will turn freely, the problem could be that the motor needs brushes. You can fabricate theses. There is info about how to do this on this website. Do a search on motor brushes, replace brushes and such.

The usual cause of these not working is a lack of use. The grease seems to gum up after a decade or so. Lithium spray grease could be useful, as could WD-40 or some other penetrating oil. Make sure to lube it with real grease before you reinstall the motor. WD-40 evaporates. It is good only temporarily as a lube.

The window is attached to the regulator by a slide device. You might have to remove the rubber track and the bottom bolt of the triangular window to disconnect the window from the regulator.

I would remove the motor and fiddle with it first.

These motors are rather expensive, but you can find one pretty cheap if you look on the Web. If you go to a boneyard, it must be a driver's side rear motor. They are not interchangeable from side to side or front to rear.

Good luck!

drskipper · #7 09-30-2007, 04:52 PM

Ok thanks i'm still unsure of how to remove the motor do I reach in behind and try to get it out that way or take the front panel off the door exposing the insides if that can even happen.
Thanks, Martin.

Richard Eldridge · #8 09-30-2007, 05:57 PM

I have replaced the motor on the front passenger door of my 85 300TD.

As I recall, the motor is held in place by three bolts, 10mm as I recall. Two can be seen on the inside of the door ands can be removed easily, a third is on the backside of the motor and you will have to feel around behind the motor. The outside panel of the door are welded on.

To remove the regulator, you will have to remove the back channel the window rides in and to unbolt or unscrew the rear frame, as well as to unbolt the window at the bottom.

You probably will not have to remove the regulator to remove the motor. You just unbolt it and disconnect it from the wires. This probably means you will have to unsolder them. The motor seems to be in the upper front corner of the door in your picture.

Again, good luck.

FRANKNBENZ · #9 10-01-2007, 01:02 AM

Hey, Martin,

Talk about timing! I was just searching the forum threads to see if anyone thought the forum needed a DIY on W123 rear power window regulator R&R. I just did my third in a week...guess that makes me a specialist. We'll see.

I have three 85 W123's. I am hoping your 81 is built sort of the same.

All good points in above posts regarding power, wiring checks, etc. Yours indeed may be one of those. My home shop has a Greenlee multimeter (part of a $30 set of toys I got at Lowes Home Stores) I would use that to do the preliminaries re DC (that's the V with a __ under it, not a ~, which = AC current).

Your problem may be the fuse, but do not be too quick to replace and try again. The motor, if still good, may be binding mechanically. Forcing it may damage the motor, bend the backing plate, and/or blow the new fuse.

Here's how to pull the power rear window motor-regulator assembly out for inspection, cleaning, alignment, and reinstallation:

1. Preparation. 10mm long socket on a 3/8" ratchet, 10mm nut driver, rags, brake cleaner, lube, wire cutters, stripper, terminal strip, small flat screwdriver, 10mm ratcheting combination or ratcheting double box end wrench (since yours is stuck up, this would be a good investment...got mine at Sears). I use a Rubbermaid dish basin to capture all parts and tools. Use something similar to ensure no small screws, bolts, nuts decide to escape.

2. Remove door panel and plastic weather barrier. (Done).

3. Note the seven 10mm bolts or nuts to be removed (see photo #1)

4. Normally, here is where you would power the window down so you can get at the two slide attachment bolts. Yours is stuck up. No sweat.

5. Reach inside and follow the rear window guide, up and down. This guide has a rubber-felt U-shaped thing in it that guides the window down to its lowered position. The guide is secured by bolts #4 and #5. Normally this guide just has to be partially loosened, but yours is stuck up so you will have to GENTLY separate the rubber felt guide liner from the stamped metal guide.

6. The stamped metal guide has two attachment points. On the lower end the #4 bolt goes through the door structural panel into a nut weldment on the guide. On the upper end of the guide, bolt #5 goes through the structural door panel, then through a flat U plate on the guide, then into a nut welded onto the upper window guide. Please note this relationship. Hold the guide in place and remove bolt #5 to inspect the elements described for purposes of accurate reassembly.

7. Remove bolts #4 and #5. Rotate the stamped metal guide 90 degrees on the long axis and it should come out with no or little trouble. Try to work around the rubber felt guide insert which will stay in the door.

8. Option. What I do is now cut directly across the black and green wires running along the door from the regulator motor to the female plug assembly

(where the switch plugs in). I cut about 30mm (1-1/4") away from the plug. I carefully strip 2mm from all four wires.

9. Loosen the motor cable by removing it from the two nylon retainers.

10. Remove bolt #2, and nuts #1 and #3.

11. Now be careful. The regulator is attached to the window via the slide. Once the regulator-motor assembly is pushed into the door to free it, gravity takes over unless you have a good grip on things.

12. The objective is to push the regulator-motor assembly into the door cavity such that the arm connecting the regulator to the slide is allowed to rotate more vertically. While still hidden from view, this rotating action will clear the arm from the rear bolt on the connecting slide.

13. The regulator-motor assembly is about 3.5kgs (8 lbs). Push it into the cavity and rotate it down to the bottom of the door interior. The window may follow down maybe 52mm (2"). The two connecting bolts should now be clear, even if not visible.

14. Techniques vary, but here you may wish to secure the window in the upper guides. I ensure both sides of the window are clean, then affix one end of about a meter (3') length of masking tape on the outside, over the door top, then to the inside of the glass.

15. Feel for the bolts on the slide and remove with the ratcheting box end (or combo). Once free, you can leave the assembly in the cavity.

16. Since I cut my wires, I thread the leads back through the access hole in the structural panel. On the shop bench, I clean up and check the regulator-motor assembly for binding, alignment, etc. See photo #2 for an example of bad alignment. The backing plate holding all this stuff is pretty base metal and not too stiff. MB must have spec'd this for a reason.

17. Using the bench, some wood blocks, some clamps, and muscle power, I get the unit all back into some semblance of alignment. Photo #3. I never clamp anything on to the arm or cog assembly, only the base metal backing plate. Note also in this photo the white nylon terminal strip (Radio Shack, others). It's used to connect up the wires cut earlier.

18. Clean, lube, bench test with a battery or charger and back it goes. The only deviation from reversing these steps is to power rotate the lifting arm down to its stop, then lower the window manually down to mate up with the slide, two bolts, test ten times via the rear switch, ten via the console switch.

19. Almost back together, photo #4 shows a very non-MB use of a cut up Hefty Bag pasted on by 3M 77 adhesive.

Please note that my regulator issues were more the bending of the base metal backing plate, resulting in misalignment of the motor gear and lifting arm cogs. Symptoms were a clack-clacking that would be heard as the window jittered or just wouldn't budge. Straightened out, lubed up, and reinstalled, sweet silence.

If I may not have made the above clear enough to follow, please do not hesitate to ask any questions or send and IM.

Good luck.

drskipper · #10 10-01-2007, 03:04 AM

Wow Thank you soo much! That was great timing. I only have one problem I dont know if this changes anything but my window is stuck down

KAdams4458 · #11 10-01-2007, 07:59 AM

Sweet post! so, the clacking in the rear regulator assemblies of my car may not be stripped teeth, but a misaligned assembly. Very interesting to know, and it's something that can wait until my car is safely in the parking garage of my complex.

Thanks!

FRANKNBENZ · #12 10-01-2007, 05:22 PM

Not really.

I rechecked the pix in your link and apologize for jumping to an erroneous conclusion. The 10mm bolts connecting the window holder to the slide are clearly visible. Don't remove them yet.

From the pix I can only see the lower bolt head (my #4) fastening the lower window guide assembly (stamped metal and rubber-felt) to the door structural frame. Check the upper end of this guide assembly to see if that location may have been improperly assembled. Remote chance the window may be finding on that. Probably not, but check anyway. Ensure the upper bolt is present and tight.

If all that looks good, chances are the stop may have worked loose and is now missing or moved. This is a widget that may be just visible in your pix as a white blob (the nylon pad). It is mounted by one 10mm hex head bolt to the regulator arm. If the stop is not there or it has worked free, the window assembly may have been allowed to come down too far into the door cavity. Again, we are addressing this as if it were a mechanical issue.

Going back to the guide, check that the two bolts (my #4, #5) are reasonably tight, then remove the two bolts from the slide with your ratchet or box wrench. Note the relationship of the slide, note the two little lugs from the window keeper go into two recesses in the slide.

You should be able to push the now freed-up window into the closed position and affix there with tape up and over. If you can't move the window, you have confirmed that the problem is mechanical.

With the window up and taped out of the way, replace the fuse -- even if it looks OK, replace it -- and then try operating the windowless regulator briefly up or down. Not too far up or the motor gear will run out of lift arm cogs.

Check the lower guide again to ensure nothing is bent and the liner is still in place. One of mine was squeezed shut on the lower end; pulled out the liner, took the guide out and bent it back in shape.

I recommend removing, cleaning, inspecting, aligning the regulator-motor assembly while everything is apart, but that's your call.

Please post results or ask questions here or via IM.

Good luck.

drskipper · #13 10-09-2007, 11:33 PM

Hey there, I'm half way there I have the window up now and a piece of wood propped under it to hold it up.
The window motor is out with the assembly, my next step is to bench test the window motor and try to get it running if not I'll get a new one.
Anyone got any good advice on how to take it apart(Motor) and what I should be careful for? what tricks or what is done to try to get it going?
Thanks Martin.

FRANKNBENZ · #14 10-10-2007, 01:20 AM

Martin,

If your assembly looks like the one in my photos, I think three 10mm bolts hold the motor to the base metal backing plate. First time around, it is always good to get a Sharpie marker and place indices (marks) motor to plate to make reassembly easier.

Do a continuity check on the motor to see if there is a short somewhere in the windings.

As a DC motor, connecting the leads one way may spin the shaft CW; reverse the leads, you get CCW. Simple stuff.

I'd test it connected back to the door switch. That way you do two tests in one: the motor, and the upstream circutry.

I doubt you will need a new motor, but if you do, pick and pulls should be able to fix you up. I use Potomac German Auto. They have two bone yards, one in MD, the other in FL. Check them out online at
http://www.mbpartsonline.com/rpm.html
Great website on which they rate their parts. First time I bought I checked prices and availabiilty online, then called. Folks are great.

Good luck.

desert240d · #15 08-08-2010, 10:27 AM

My latest gremlin fix has been working on the rear power windows in my '83 300D. The driver's side was cured by a rear switch removal and cleaning. The passenger side was described by Franknbenz's clack-clack-clack sound and stuttering. After reading his awesome post on removing and re-aligning the motor/regulator, I tackled the task and completed in about two hours. My motor and regulator were badly misaligned, and the pot metal holding the motor even had an inch crack in it. I realigned to specs close enough for Santa Fe (government work)

, and for the time being have all of my power windows functioning smoothly. Thanks and props to Franknbenz for his detailed and money saving write up.