W124 rear window regulator

A week or so ago I was returning from a family event in my 300TE.  My son in the middle seat in the rear and my two daughters on either side.  Out of nowhere, the dulcet tones from the Becker radio were interrupted by flatulence so powerful it could have been measured on the Richter scale.

The source quickly revealed itself when my two daughter started gasping for air, desperate to escape the noxious cloud that now enveloped them.   Like a safety alarm, they reached for the only things that could save them, the window switches.  The passengers side rear window slid down easily, and that side of the car was bathed in sweet carbon monoxide fumes from the M4.  On the drivers side, a loud crack emanated from the window mechanism when the window was only down 5cm.  There the window stubbornly remained while my younger daughter lamented on her certain death.

Yet by providence, her life was somehow spared, and when the fumes eventually cleared we were able to return home and live to tell the tale.

With all three children still alive, only then did my thoughts turn to repairing the 300TE.  I was surprised by the noise the window made.  I’ve dealt with window regulators in old Mercedes before, but not with a failure that sounded like that.

Doing more research, it became apparent that the rear doors on a 124 use a cable operated window regular rather than a sliding jaw type.  The crack was clearly the cable letting go.  I ordered a new one from Spareto, a Vaico unit.   There were a couple on eBay a bit cheaper from brands I had never heard of.  Even better news was that wagons used sedan regulators.

The instructions from the workshop manual were fairly straightforward.  The hardest past was the trim around the door handle.  The way it moves forward is not all that well described.  In general I don’t think the door trim is as good quality as earlier Mercedes.  It seems to be made from some kind of material that is a hybrid of wood and cardboard?  It lifts up to come out, like traditional Mercedes trims, but the ‘hooks’ are mostly glued on.  Most of mine had already come off.  It looked like the trim had been off before, as there was hardly any moisture barrier.

Getting the old Regulator out was fairly straightforward.  Two bolts for the regulator, one top and one bottom. Three nuts for the motor.  The manual seems to say you need to remove the slider thing that holds the window to the regulator before removing the regulator.  I found that only possible with the regulator unbolted.

Unlike the older type window regulators I am used to, this new one came with a motor.  I don’t know if the one I had removed was original or not, but if was certainly a proper Mercedes-Benz part.

With the old regulator out, I found that the cable hadn’t snapped, it had managed to work its way out of the runner.  Not sure if it is repairable or not, but I didn’t try. I just fitted my new one.

The new one went in pretty easily.  The Vaico regulator used different wire colours.  Blue seems to go with green, and red with black.

With the new regulator fitted and working, I then glued the hooks back onto the door trim.  I let it sit to dry, and I will also make up a new moisture barrier before I re-install it.