123 window lift motor? - PeachParts Mercedes-Benz Forum

Hank Fisher · #1 11-04-2009, 07:45 PM

Hello Forum.

After a mere 344,000 miles my 1985 300D seems to be blowing lift motor circuit fuses when I try to raise or lower the driver's window.

After the first fuse blew, I lubed the regulator linkage with white lithium grease. It worked for about two or three weeks, and then blew the second fuse. Then the third one blew immediately after it was installed and switched on.

Now I am thinking that I may have a worn out lift motor. But, to tell the truth, I don't know if that is really the problem or not.

Have any of you been through this problem? Any tips on correcting the problem? BTW, the part does not seem abundantly available in the places I have looked online. If I cannot find the motor, is it a reasonable and do-able thing to convert it to a hand-crank window lifter? Inasmuch as I intend to drive this old car clean into the ground, such a thing is not beneath my dignity. After all, it still drives just like a Mercedes.

Thanks for reading this, and for your expertise.

Hank
1985 300D 344K; 1991 300SE 160K

rscurtis · #2 11-04-2009, 08:26 PM

I had a similar problem with my 300 and I removed the regulator and disassembled the motor. The bearings were frozen. A little cleaning and lubrication and good as new. Since the window was stuck in the closed position, i removed the motor from the regulator while it was still in the door.

Hank Fisher · #3 11-04-2009, 08:37 PM

Quote:

Originally Posted by rscurtis

I had a similar problem with my 300 and I removed the regulator and disassembled the motor. The bearings were frozen. A little cleaning and lubrication and good as new. Since the window was stuck in the closed position, i removed the motor from the regulator while it was still in the door.

Hello rscurtis.

Thank you very much for sharing your experience. Mine is presently in the UP position also. I will try to do what you did. Anything to know in particular about taking the motor out and putting it back? Is it intuitive, in other words? Are there any spring loaded surprises or such?

What was the mileage on your 300 when you did this? I am just wondering if the brushes might be worn out in mine. I guess I'll find out when I get it open.

Thanks again.

Ian White · #4 11-04-2009, 08:45 PM

Probably extreme sustained brush/contactor wear or an extremely worn commutator. Could also be sticky bearings as previously said...

toomany MBZ · #5 11-04-2009, 09:12 PM

You may need to help the window down 3/4 of the way to gain access to remove the regulator so you can remove the motor to troubleshoot.
Remove the door panel, lower the window till you can get to the three bolts at the bottom of the window.

rscurtis · #6 11-05-2009, 10:21 AM

Hank, in order to remove the regulator, I removed the motor while it was in the door, then I could remove it. The car has 116,000 miles on it,but I think the motor problem was more of a function of age. Disassembly is straight forward, just be sure to hold the armature in place when re-installing the motor housing as the magnets will try to move the armature. The motor was in fine shape, just needed lubrication.

blindwolf · #7 11-05-2009, 12:28 PM

Have you checked the wiring where it runs through the door. The insulation may be frayed and shorting out.

charmalu · #8 11-05-2009, 12:29 PM

Just did a search in All Parts and Fast Lane, and no L/F motor.

Would a L/R window motor fit onto the gear assembly of the L/F motor?
The rear windows don`t get the use the drivers door does, so the motor
should be in ok shape.

Charlie

Hank Fisher · #9 11-10-2009, 04:41 PM

Thanks, Guys.

Thanks to each of you for your input into this thread. I will be tackling this problem within several days. I will report what I find when I get into it. I appreciate the guidance more than you know.

Happy day.

Phil · #10 11-11-2009, 10:55 AM

The attached picture is of a window motor from my car and the bushings are circled in red. The lubing ability of the bushings tends to dry up over time. I took the motor apart and lubed the bushing about 3 years ago and it still works fine. It was not easy to get the lower bushing out as it was stuck on the shaft and the clip that holds it in the body didn't want to come out with it but I just kept after it and it finally came apart.

Hank Fisher · #11 11-11-2009, 11:55 PM

Quote:

Originally Posted by Phil

The attached picture is of a window motor from my car and the bushings are circled in red. The lubing ability of the bushings tends to dry up over time. I took the motor apart and lubed the bushing about 3 years ago and it still works fine. It was not easy to get the lower bushing out as it was stuck on the shaft and the clip that holds it in the body didn't want to come out with it but I just kept after it and it finally came apart.

Hello Phil.

Thank you for that image. That will doubtlessly prove useful as I take the motor apart for cleaning and lubing. I am hopeful that the brushes and rotor contacts are still okay. But after daily use for 344K miles and 25 years, I do have some worries about it.

I am having some trouble knowing exactly how to get the motor out. I found a Mercedes service manual "Chassis and Body Series 123." On pages 72.4-185,186 it describes how to remove the front door electric window control (window lift with motor). It's confusing. Here is the sequence of steps it lists: [There is no procedure for removing just the motor.]

1. Remove door liner. (72-100)
[No problem. Snaps and screws. Intuitive.]

2. Remove plastic sheet.
[No problem. Ripped it loose. I will glue it back later.]

3. Run down crank operated window and remove front screw on window lift rail.
[There is a picture of the screw. However, how to run down the "crank operated window" is a mystery. There is no crank that I can see. From your picture, I cannot understand how that the motor can be detached from the large round gear which it turns, without removing the entire assembly, that is to say the lifter regulator with motor attached. It is also a mystery as to how the regulator attaches to the glass.]

4. Remove rear screw on window lift rail.
[There is a picture of this with the lift all the way down. A straight forward step, if I can get the thing "cranked" down, however that happens. In my window lift's present "up" position, the screw is not there, and is not visible.]

5. Raise crank operated window and hold with a wedge.
[ I guess they mean to physically move the glass up and jam it with a wedge so it won't fall down. I can probably figure this one out.]

6. Disconnect electric wires at connector.
[Good picture of terminal strip. No problem.]

7. Unscrew three front nuts on window lift and both rear bolts on window lift.
[ Straight forward. Good picture pointing to these. I can do this.]

8. Remove window lift with motor downward.
[ Picture shows the compressed "down position" lift and motor coming out of the large hole in the door. I think I can do this if I can get the regulator into the "down" position.]

9. (Installation) Install in reverse sequence. Electric wires of same color are connected with each other.
[If I get it apart, I am optimistic that I will get it back together.]

Note: Bottom stop is adjusted with screw.
[ A picture shows how to adjust the bottom stop.]

And again, if the motor does not run, then how does one "crank" the window down so that the "scissors" of the regulator can compress to be small enough to get the regulator assembly with motor out of the hole in the side of the door?

Thanks, everyone, for reading my posts here, and for your help.

Hank Fisher · #12 11-12-2009, 12:50 AM

Quote:

Originally Posted by rscurtis

I had a similar problem with my 300 and I removed the regulator and disassembled the motor. The bearings were frozen. A little cleaning and lubrication and good as new. Since the window was stuck in the closed position, I removed the motor from the regulator while it was still in the door.

@rscurtis:
My window is also stuck in the "up" position. I think you are saying that somehow you got the motor free from the scissor-like regulator assembly, and removed only the motor from the door. I would like to do this too, if that's all I need to do. Did you remove the motor only, or was that just a step towards getting the regulator assembly out? It looks to me like one of the motor bearings is up inside the larger gear assembly, judging from Phil's photo blowup.

I see two of what appear to be Torx headed screws where the motor meets the gear assembly. If I can get those screws out, will I be able to pull the motor and its worm drive gear straight out? Will the "regulator scissors" then compress and allow the window to come down? Does the window fall, or does it need some help getting down?

@Phil and rscurtis:
What type of lubricant did you choose to use on the motor bearings when you worked on yours?

Quote:

Have you checked the wiring where it runs through the door. The insulation may be frayed and shorting out.

@blindwolf:
Thanks for the tip about the wiring. I'll check that.

Thanks again!

Hank Fisher · #13 11-12-2009, 01:44 AM

Quote:

Originally Posted by charmalu

Just did a search in All Parts and Fast Lane, and no L/F motor.

Would a L/R window motor fit onto the gear assembly of the L/F motor?
The rear windows don`t get the use the drivers door does, so the motor
should be in ok shape.

Charlie

Hello Charlie.

I am hoping big-time that I can get it going. I got a quote in the "over $250" range for the motor. It would be interesting to know if the motor from another regulator would work, if the one I have cannot be brought to life again. In that case, it seems like even one from a parts car would probably be good enough, since only the driver's door sees heavy, everyday use.

toomany MBZ · #14 11-12-2009, 10:38 AM

I'll agree getting the window down a bit without power is a trick. My failure was the regulator, so I able to lower it. You may be able to get power to the motor itself, bypassing the switch and wiring running through the door. Yet if the motor is toast, that won't work either.
You're other option would be to try and reach up to remove the bolts holding the regulator to the window glass at the bottom edge or trying to remove the motor, as you've mentioned those go in from the back, but the window bolts go in from the front.
Good luck.

Phil · #15 11-12-2009, 11:13 AM

In the first picture you can see the two elec. connections on the lower left. Before you remove the motor try jumping a wire from ground to one connection and 12 volts to the other, if nothing happens reverse the wires. If the motor works this way then your problem is in the wiring or switch. I found that I had broken wires at the hinge area of the door.
If the motor still doesn't work then you will have to remove it. The first time I took one out I removed the two screws that held it to the gear head and then rotated the motor until it came out. The second picture shows the location of the two screws that you would have to take out to do this. When I have had a stuck bearing it has always been the lower one so getting the motor out was not a problem. In the third picture it shows the location of the upper bearing and if you can just get the motor out you can put some white lithium grease on the shaft when you put it back together and it will get into the bearing.
When I removed the motor and gear head I put a block under the window to keep it up and was able to remove the mounting screws and bolts for the gear head and slide just that part out. As I remember there are 3 screws and bolts and you have to reach around behind the gear head to romove some but it can be done.