The Car...1988 300SEL (W126 Chassis)

I'm trying to replace the front passenger window regulator. I have had the regulator in and out three or four times. Every time I try raise the window with new regulator installed it keeps binding up after a couple of inches of movement and stops moving. After so more poking around I found the part pictured wedged in at the top of the window, not really connected to anything. Can someone tell me what this part is and how it gets installed...

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The plastic part is the same size and shape as the plastic slider on the window regulator, so I can guess that it goes into the metal part at the bottom of the window, where the rest of it goes I don't know?

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That looks like the plastic sliding jaw... I would go to a junkyard, take one apart and see how it fits together?

Does the window work properly with that part out of the way?

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

That is not a very good picture. Does your camera have the "flower" setting for closeups? It is hard to see what is there.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

Well...yes and no. Without that part the window no longer binds up, but it keeps slipping out of the front and rear window channel. I'll see if I can get some better pictures of it tonight when I get home.

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I just did this job on my '87 420SEL, but I didn't have the problems that you're having. The problem may be that, when something is jammed so the window motor can't go through its entire range of motion, it exerts a lot of force on the lifting arm and on the motor's three mounting points, and this can bend the lifter arm or said mounting points. It sounds like the lifter arm is bent or cocked so it is not lifting straight up and is instead trying to shove the window out of its channel. Also, if the window can jump out of its channel, there must either be something in the channel itself that it causing the window to jump out, or the channel may be set too loose, or the channel might be broken or defective. You can adjust the channels by loosening their mounting bolts and sliding them toward the window. Check the lifter arm and the interior door sheet metal, where the motor mounts, to make sure nothing is bent. You might need to compare the lifter arm with the one from the other door to see if it is bent.

Thanks, what I know about photography can be balanced on the head of a pin. The help is appreciated. I took some more pictures of the mystery part, they are attached and hopefully a bit easier to see. About three weeks ago I finished rebuilding the front suspension on this car, I rebuilt everything...new upper control arms, new lower control arm bushings, new lower ball joints, new spring pads, new guide rods, new guide rod repair kits, guide rod mount, bearing bracket bushings, tie rod ends, drag link, steering damper, eccentric pins, shock absorbers(Bilstein HD), brake rotors, wheel bearings, brake pads..doing all that was easier than replacing this damn regulator

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Look at this thread, especially diagram in post 2. Is that part# 35 the one you have?

126 window regulator question..

I searched on "126 window" and found lots of threads including this one. You might do the same search and look at some of the other threads also.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

Yep, part 35 looks like the culprit., Thanks, I'll read through the other threads.

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You can allways take the inner door panel of the other front door & look at it's design.
I believe that is a slider. Without the slider, there should or may be a 'clunk' as switch is pressed from up to down.
When you assemble the regulator, look at the door weep holes & make sure they can drain.
Also the lub. un the slider is important in cold weather. I use Lubrplate. Any good engine shop has this & will give you a dab ... you don't need a lot.
Also look at the regulator gear. If motor forces the window till gammed, the regulator teeth often strip. Sometimes the regulator frame cracks making the gears missaligned & a strange wear pattern.

Thanks for the advice. I had thought about taking apart the drivers side door to see how it is put together. But, given how delicate the tabs are on the door panel I was trying to avoid it if possible.

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I figured out where the mystery part goes..see attached photos. The slider end goes into the window slider track behind (towards the rear) the regulator slider. Window works great now.

Attached Thumbnails

       

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I'm sick of .sig files

Thank you for posting the solution! And with photos!!!

Was it part # 35 ? It doesn't look like it. Do you think it will fall off again?

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra