1980 450SL Window Issue

[rmasteller]

Hi. I bought this car last fall with this problem pre-existing on BOTH windows.

When wanting to put the windows up OR down, they only move a short distance - maybe 3 inches. The motor groans and the glass stops. I pull up or push down on the glass, use the window switch again, and the glass moves another 3 inches. Repeat until window is all the way up/down.

I took the door panel off, cleaned the tracks as best I could, and sprayed Liquid Wrench lithium grease on them. This didn't make any difference. Then, when testing the cleaned & lubed tracks, I noticed that the small gear on the lift motor goes around once for each of these cycles. So, I though there may be something caught in the gear, or the gear may be damaged some how. After my best attempts at cleaning and inspecting, I can't see anything wrong with this small gear (pictured below).

What other diagnosis should I perform to determine if it is a physical problem (gear, tracks, or lift mechanism), or a problem with the motor?

Thanks!

[nh500sl]

I would place a bet on the motor.

[meltedpanda]

yup , sounds like the motor is sick , the brushes or armature.

they just get tired after a lot of years, can you turn the gear and raise lower the window by hand, should not have any real resistance

[rmasteller]

Originally Posted by meltedpanda

Can you turn the gear and raise lower the window by hand? Should not have any real resistance.

Turn which gear? And how? Are you saying grab a gear with my hand and turn it? USe a tool to turn a gear? Or, are you saying grab the window and pull up/push down all the way?

[meltedpanda]

it looks like the motor is off correct, yes the gear it goes to. Turn by hand or fabricate a "turner" of some sort.
before id do that I'd ck the motor off car with 12v +/- and then reverse polarity see how it sounds runs

[rmasteller]

Thought I'd follow up on this old thread. It turned out to be the electric window motors. Well, not the motors themselves but the large white plastic gear inside the motor case. This gear has worm-style teeth that turn the shaft that turns the gear in the window lift (regulator?) mechanisim. This plastic gear had teeth sheared off creating a dead spot. When pulling up on the window glass, it moved the internal parts just enough to get them to grab again and allow the plastic wheel to move around one more time and find the dead spot again. This was the issue in each door. I got good used motor assemblies and replaced them.

[meltedpanda]

good for you, and I like when threads have a close!