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Old 01-23-2013, 09:45 PM
Registered User
Join Date: Oct 2007
Posts: 70
Question 1985 300 CD Window Motor replacement question

Hi Everyone,
I've been told that I need to get a new window motor for my drivers front window. Previously, the window would go down and then I would have trouble (at the most inopportune times) to get it back up.

My indie says that it's not the switch but the motor that needs to be replaced. My question is, are the motors interchangeable? I can't seem to find a motor specifically for the drivers front window, but rather I see plenty for the back, and both windows on the passenger side.

I've searched and read that 99% of the time, it's NOT the motor that is the problem so I wonder if my indie perhaps made a mistake.

Is it difficult to take the door apart and test the motor? Can someone recommend a step-by-step procedure on something like this?

Thanks for your help.


1967 Dodge Coronet R/T (SOLD)
2001 Volvo S80 (Accident; bought by Insurance)
1996 Volvo 850 Wagon (SOLD)
1982 Mercedes Benz 240D (Accident; bought by Insurance)
1988 Mercedes Benz 300CE (Deer Strike; bought by insurance)
2002 Volvo XC70
1985 300 CD
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Old 01-23-2013, 11:19 PM
fashion victim immunizer
Join Date: Feb 2012
Location: oakland
Posts: 930
i think the motors are pretty bulletproof.. its the regulator that is the problem.
1981 NA 300D 310k miles
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Old 01-24-2013, 10:35 AM
Registered User
Join Date: Aug 2011
Location: Carolina
Posts: 1,395
how does the window move when it is working?

i'm gonna chime in and say that i too believe that the motors are pretty much indestructible.

i would try to isolate the problem to either definitely the motor or the electrics before i went through the trouble of trying to switch a motor.

answer the original question.. Yeah. i do believe that the motors are interchangeable.
Current fleet
1992 300D "IceBerg"
1984 300D "Blues Mobile"

1978 300CD "El Toro" Gone on to be born again
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Old 01-24-2013, 12:05 PM
Diesel911's Avatar
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Join Date: Sep 2007
Location: Long Beach,CA
Posts: 31,222
One way to tell if it is the Motor is to sit a Car Battery near the Door and make some Jumper Wires to Hot Wire the Motor directly.
Don't have experience on your Year and Model but on the W123s the Motor is not grounded to the Chassis as part of the Electrical Circuit like your Starter Motor is. (It could be your Mechanic does not realize this; I also though My Motor was dead till I tried it.)

If you have both Motor Wires in hand connect the Jumper Wires one to one terminal and wire and the other to; the other termnal and wire and the window will go one direction.

Swapping the Wires on the Battery Terminl cause the window to go the opposite direction.
If the Window work like that you have an issue somewhere else.

One of the other issues is that sometimes the Brushes inside of the Motor are worn. People have gone inside and replaced the Brushes.
84 300D, 82 Volvo 244Gl Diesel
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Old 01-24-2013, 03:55 PM
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Join Date: Nov 2007
Location: Cameron Park CA
Posts: 1,863
These motors fail just as often as the regulator but in my expierence they just stop working one day. Moisture and rust is always founds inside the motor if the gasket has gone bad (so if you do replace the motorput some silicone in it first). If your windows slow regrease the tracks with soap grease and play with some of the adjustments on the door (sliding bolts). If these dont help power the motor directly to rule out a high resistence connection. These cars are getting to the point where the wires in the doors are actually cracking.

1981 300SD 512k OM603

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