1985 300D - Passenger Window Problem
 

Another day, another problem.


The front passenger side window on my 1985 300D (electric windows) is only moving halfway up. The fuse is fine. All other windows function properly. I don't think it is the switch or wiring ... why would it stop in the same spot every time if that were the case? There is a binding or cranking noise coming from the door panel when it stops mid-way. Do these things get misaligned, off-track or rods or guides inside the panel bent or broken?

Thanks for any advice.

You probably need to remove the door card and take a look. They are designed to pop the sliding jaw but sometimes the regulator arms will bind and bend before it pops. Sounds like you may be close to that.

Thanks. Sounds about right. There is definitely a binding thump coming from inside the door panel. How hard is this to repair?

You are probably looking at the need for another window regulator. You can probably find one at your local pick a part for less that $20. Not too difficult to install.

Random comments.

There is some threads on taking the Motors apart to inspect them and change the Motor Brushes.

Dorman I believe sells aftermarket Front Window Regulators but you need to make sure they are not for Manual Windows.

When you pull off the Door Panel on the front bottom is a wire terminal block. Make sure the terminals are clean and the screws holding the wires are tight.

The window switches can be the source of odd issues. The switches can be taken apart and in my case I used a small pocket knife to scrap off as much of the black burnt parts on the Contact Points as I could. There is instructions on doing that in the DIY section.

Sounds like new regulator time
 

What happened on two of my w126 windows is the gear teeth on the regulator wear down and the motor gear starts jumping trying to get to another tooth if that makes sense. In other words the regulator has a semi-circle shaped plate with teeth on it that mate with the motor gear. These teeth wear down midway on the plate resulting allowing the window to raise to mid level and then stop because of the missing (worn teeth). In my case it was about halfway up where the window frame starts to curve and I believe puts more force on the teeth.

Door card = door panel. To remove the card you'll need to remove a couple of items: door lock pull screws off, panel arm rest (3 screws), interior trim at back of the door inside the window frame (tiny screw) at end of door, and the interior door latch.

Once those items are removed, slide the panel upwards approximately 3/4" and then remove. Maybe there is a plastic sheet that you'll need to pull back to access the window regulator

Thank you all very much for your considerate replies.

Be aware that it's probably a lost cause looking for a good rear regulator for a W123 in the junkyard. They are all just as badly bent as any that are likely to be in your car. It was just a design that didn't stand the test of time, unlike much of the rest of the car.

Your best bet may be to remove your current regulator to look it over before it breaks worse - see if it's just bent and you can try to bend it back in to shape.

If on the other hand you find it's the motor that is acting up you can see about repairing it, or picking up a good used motor. Those are easy to find, as the motors themselves are very robust.

Good luck, and check out the link in my signature for some guides on pulling regulators, bending them back in to shape, etc.

Is there any way to get it all the way up and leave it as such?


... for the time being, at least.

Probably not. I had good luck bending one regulator arm back straight; has been several years now - maybe ten or so. Had to replace the sliding jaw and straighten the arm. 1981 300SD but windows probably same as yours.

The W126 regulators are different, in back anyway. More durable design.

It can't be raised and wedged?

If you take out the panel and remove the regulator/motor you can wedge the glass up, as it will then free moving in the rails.

But while the regulator is in there and likely stuck/jammed, no.

So you'll need to start by removing the panel and checking out the situation, and probably plan to pull the regulator. Wedge the window up (I've used a length of 2x4 before myself) and then start looking at fixing the regulator or replacing it.

Thank you!

sometimes - if you have a helper - while the window is on the way up, with the door open, have a helper put their hands on both sides of the glass and pull upwards to 'help' the glass along. You may get lucky and be able to get the regulator and motor teeth to catch again on the other side of the possible worn gap. Good luck!