1995 S124
I have done a few of these over the years ... typically an easy swap, always straightforward, 30-60 mins depending on doorcard co-operation .
However ...
I have just had a rear window start to struggle to get much past 3/4 closed before giving up. I keep the channels cleaned so presumed it to be a motor/cable problem unless finding gunk buildup inhibiting the teflon slider on the rail once exposed, which is very unlikely.
So with Rob Parker (thanks Rob!) standing by to send a replacement I took the doorcard off in order to double-check before sending payment, and instantly could see what the real cause of the problem was.
The three isolation mountings securing the motor-body to the inner doorskin had failed through the rubber section. The photo shows just what a state the mounts were in, no doubt it had been holding on one for a time now until that finally failed too.
This meant that although the regulator's cable track was firmly secured to the door by its top and bottom bolts, the small amount of displacement movement available at the offset motor-position when it was operating was being partly transferred and causing the alignment angle of the glass to shift just enough so that the window couldn't complete its travel without eventually binding simply from interference. Operated out of the car the regulator purrs smoothly all the way.
So if your window doesn't fully close, don't just expect it is worn and replace it, check these mounts. One clue before you even start is the glass-angle as it raises, which you can easily check visually from above - look for whether the angle of the glass seems too much at odds with the channel it is trying to rise into; another would be the lack of slipping-gear noises from the motor, suggesting that it has probably not failed through drive-wear yet.
Bear in mind that because the cable track is firmly secured top and bottom you can at first get the impression that the whole unit is pretty firm itself. The isolation mounts are tucked away because the motor is offset, but you can get to them enough to see if they have a line through them: see if operating the motor or just leaning heavily on the motor-base - not the cable track, which is where you first want to grab it but that's bolted in place and won't move anyway - makes a suspected mount failure-line open up completely or at least become more apparent.
If you are still not confident however, then just take it out anyway it is simple to do at that stage, and it will be easy to verify.
If even one of the mounts is still sound I'd expect the windows to be operating perfectly normally, so if this is actually a cause of your problem I'd expect all 3 to have failed and the fault only noticed once the last one went.
And if that's the case your fix is probably just three new mounts instead of the cost of a replacement unit whether new and worry-free or used and limited-life. Either way it is no more work really, you have to take one unit out and put one unit in - hopefully it might just be the same unit in both cases once you have replaced the mounts.
And yes I know that it is no great cost or problem just to replace the whole thing one way or another anyway, but that's SO not in the spirit of 124 maintenance!
I'm thinking this is likely applicable to other MB models also.
3 MB dealers have now told me there are no new 124/rear units in the UK at this time (Mar 2018 if you have come to this later) nor in Germany right now and they are backordered and awaiting estimated availability.
So I'm going to explore availability of these mounts first as they must be used elsewhere, or a suitable equivalent. I'd rather re-fit a known-good unit with new mounts, than an uncertain used unit with mounts that themselves may well also be on borrowed time by now.
So ....
In the meantime, if you have come across these in the photo or similar please let me know ... overall length is 3cm, threaded sections 7mm one side 12mm the other though longer can of course be shortened to suit. I have no idea what the thread is, but thread pitch gives 6 turns/peaks per 5mm, so 11 per cm ... thread measured across the peaks is 6mm, and across the troughs looks a shade under 5mm.
I have done a few of these over the years ... typically an easy swap, always straightforward, 30-60 mins depending on doorcard co-operation .
However ...
I have just had a rear window start to struggle to get much past 3/4 closed before giving up. I keep the channels cleaned so presumed it to be a motor/cable problem unless finding gunk buildup inhibiting the teflon slider on the rail once exposed, which is very unlikely.
So with Rob Parker (thanks Rob!) standing by to send a replacement I took the doorcard off in order to double-check before sending payment, and instantly could see what the real cause of the problem was.
The three isolation mountings securing the motor-body to the inner doorskin had failed through the rubber section. The photo shows just what a state the mounts were in, no doubt it had been holding on one for a time now until that finally failed too.
This meant that although the regulator's cable track was firmly secured to the door by its top and bottom bolts, the small amount of displacement movement available at the offset motor-position when it was operating was being partly transferred and causing the alignment angle of the glass to shift just enough so that the window couldn't complete its travel without eventually binding simply from interference. Operated out of the car the regulator purrs smoothly all the way.
So if your window doesn't fully close, don't just expect it is worn and replace it, check these mounts. One clue before you even start is the glass-angle as it raises, which you can easily check visually from above - look for whether the angle of the glass seems too much at odds with the channel it is trying to rise into; another would be the lack of slipping-gear noises from the motor, suggesting that it has probably not failed through drive-wear yet.
Bear in mind that because the cable track is firmly secured top and bottom you can at first get the impression that the whole unit is pretty firm itself. The isolation mounts are tucked away because the motor is offset, but you can get to them enough to see if they have a line through them: see if operating the motor or just leaning heavily on the motor-base - not the cable track, which is where you first want to grab it but that's bolted in place and won't move anyway - makes a suspected mount failure-line open up completely or at least become more apparent.
If you are still not confident however, then just take it out anyway it is simple to do at that stage, and it will be easy to verify.
If even one of the mounts is still sound I'd expect the windows to be operating perfectly normally, so if this is actually a cause of your problem I'd expect all 3 to have failed and the fault only noticed once the last one went.
And if that's the case your fix is probably just three new mounts instead of the cost of a replacement unit whether new and worry-free or used and limited-life. Either way it is no more work really, you have to take one unit out and put one unit in - hopefully it might just be the same unit in both cases once you have replaced the mounts.
And yes I know that it is no great cost or problem just to replace the whole thing one way or another anyway, but that's SO not in the spirit of 124 maintenance!
I'm thinking this is likely applicable to other MB models also.
3 MB dealers have now told me there are no new 124/rear units in the UK at this time (Mar 2018 if you have come to this later) nor in Germany right now and they are backordered and awaiting estimated availability.
So I'm going to explore availability of these mounts first as they must be used elsewhere, or a suitable equivalent. I'd rather re-fit a known-good unit with new mounts, than an uncertain used unit with mounts that themselves may well also be on borrowed time by now.
So ....
In the meantime, if you have come across these in the photo or similar please let me know ... overall length is 3cm, threaded sections 7mm one side 12mm the other though longer can of course be shortened to suit. I have no idea what the thread is, but thread pitch gives 6 turns/peaks per 5mm, so 11 per cm ... thread measured across the peaks is 6mm, and across the troughs looks a shade under 5mm.