W126 sunroof

[219]

Has anybody here replaced a sunroof drive cable before ?

My sunroof was getting slow to open and close ( sliding backwards and forwards ) , then just recently it started making a rat-at-at-tat noise when tilted fully up - this told me that the drive was missing somewhere back at the motor .

Since I have been on holiday this week , I have been tinkering with the car , and decided to give the sunroof a clean and lube , as well as inspecting the cable . I popped the interior trim down , which gave access to the side rails and easily cleaned and regreased these - this speeded up the movement a little .

Next I undid the drive cable from the sunroof bridge and motored it forward , then pulled it right out - it was very dry and dirty - a new one will be needed as I could see a section of the drive spiral at the rear end where the spiral was worn flat - hence the noise .

Anyway , until I get a new cable , I decided to clean and grease the old one and put it back in . Having done this , I slid it back down the tube , a little tight in a couple of places , presumably where it goes round bends , but got it back in to about six inches from end .

Problem is , I now can't get it to re-engage with the motor . I have tried twisting the cable as I try to thread it in , running the motor in the close direction , disengaging the little white wheel on the side of the motor , operating the manual close wheel , all to no avail .

Am I missing something ? Do I need to loosen something off to re-thread the cable ?

Anyone been here before ?

I imagine W123 , W201 , W124 and other sunrooves will be similar .

 

[219]

OK - after a cold beer and a little more thought I solved this one myself .

What happened when I pulled the drive cable out was that the guide tube dislocated itself at the motor end . I removed the plastic cover which goes over the control relay and the timing gear on the back of the motor assembly and found that the tube was flapping around loose . I then managed to get a cable tie around it , to hold it in alignment with the gear channel - then the cable threaded back in as easily as it came out ( actually easier , due to now being lubricated ) and I now have a nice , fast sunroof .

I'll order up a new drive cable in due course , as it is at present , every time I go to full tilt , it misses a couple of cogs and the closed position goes out of alignment - easy enough fixed but needs sorted properly .

 

[ianrandom]

Thanks for this. I have sunroof work to do this summer. I plan to change the whole cartridge as i have no tilt. I have the rat tat tat noise too coming from the motor area so your post has been pretty useful.

 

[219]

Ian , it is almost certainly just a new drive cable you need . The spiral round the cable which engages with the drive gear on the motor wear .

I looked today at a couple of US sites advertising these cables and they seem to range from around $40 to $75 for various models .

I'll get a price for mine next time I'm in the dealers .

When I come to fit the new cable , I'll take some photographs and post them here .

 

[ianrandom]

Maybe, i do like the idea of doing just that. What are the drive gears made of on the motor? This is what i was going to start with. I had decide the gears were worn and a motor swap was in order. Reading your post makes it seem the cable is more likely at fault. And i didnt realise it was so easy to replace.

However i suspect my non tilt has more going on than just the cable. And on my spares car it all tilts and slides perfectly. Hence i thought to swap the lot. I hate the sound of the inside workings of the sunroof.

 

[219]

Ian , I have not removed the motor to see what the drive gear is , but on a W126 , I'd expect it to be metal . Most things that are plastic on other cars ( like the air vents ) are metal on W126's , especially parts which might wear out .

Earlier this afternoon when I was looking on the internet for information about how to refit the cable , I came across lots of sites advertising drive cables - it seems the cables do wear out quite regularly .

Since you have a spares car , you can practise on it first . Removal is easy : just slide the roof back a bit and pop the front edge of the trim down ; then hold the trim where it is with one hand and slide the roof panel all the way back ; the trim will then pull forward and upwards and can be withdrawn out through the hole in the car roof . If you then motor the sunroof panel all the way forward again , you will see where the drive cable attaches to the centre of the sunroof transport bridge ( the cross beam below the rear edge of the sunroof panel ) , there are two small bolts holding the cable to the beam - if you remove these , then press the switch to motor forwards , the cable will come out until it disengages from the motor , after that , you can pull it right out - it may be quite stiff if it has not been lubed in a while , but it should just pull out - if it seems to catch , try motoring forwards again as you may have passed a section of cable where the spiral was worn away . Once you have it out , all will be clear .

The non-lifting of your roof may be due to broken lift arms - comparison with the mechanism in the other car should make this clear - with the trim removed you can see everything working from inside . The mechanisms are not as complicated as some people make out .

If you need to replace component parts , such as broken lift arms , I would suggest this is a better option than changing the full cassette which would disturb headlining , drain channels ( which might be corroded ) and is an awkward thing to get out of the car once removed from the ceiling ( I have done it on a SEL , don't know if it is possible in a SE ; with W123 models , removal of the rear window is the usual method ! ) . The sunroof panel can easily be removed once the trim is out - it is only held to the mechanism by a few bolts which are accessible from underneath when the trim is out of the way .

Since this subject is likely of interest to others , I will take some photographs of the various parts once I get my new cable .

 

[w123ce280]

Hi Derek,

Did you get a chance to replace the cable, where would you recommend a source? My CE 280 cable broke and will require a replacement.

Kind Regards

Brendan

 

[219]

Sorry , but I replaced the cable after I found a donor car in a breakers' yard . Replacing the cable is really easy .

Just take the roof back a little and remove the trim from the underneath of the sliding panel - it just pops down from the front edge , then withdraw it forwards .


With the trim out of the way , slide the roof shut again and you will see the drive cable where it connects at the back end . On mine this was held on by two small bolts . With the bolts removed , operate the switch as if to close the roof and the cable will be pushed out until it disengages from the motor at the back ; it can then be pulled out by hand . Beware - it is long , greasy and dirty : so wear gloves and make sure you don't get grease/oil over your interior .

Putting the new cable in is just a matter of pushing it back down the outer tube until you feel resistance where it meets the motor ( this will be with six inches or so still sticking out of the tube ) , then operate the switch until the gears catch the drive cable and pull it in to the closed position . There is a little wheel on the motor which adjusts the closed position of the roof ( at least with the tilt/slide rooves on the later cars ) and you may have to mess around with this by trial and error until you reset the closed position ( you pull the wheel out , much like the winder on a watch , to disengage , then rotate a little and see what difference this makes to the closed position - repeat until correct .

I think I still have the old cable lying outside in my trailer - I'll take a couple of pics of that and post back .

Re sourcing one - a new one would most likely be a dealer part , but you could try Dave Collins ( Retrodave on here ) for a used one , or Mark Cosovich the W123 specialist .

 

[219]

OK - a few pics of my old cable which may illustrate the usual problem

Firstly , the full cable

Then the end which fits to the roof

And the end with the spiral , which is driven by the gear on the motor

Finally , the damaged bit , which will correspond to the fully open position ( tilted up ) as the closed position is governed by the microswitch , but at fully tilted up only mechanical resistance stops it and the motor tries to push against the cable ( also with fully back ) .

You can see where the spiral is damaged

Another avenue for a replacement cable - if you can't get one anywhere else , might be to try a yacht chandler . I remember being advised to do this many years ago when I couldn't get a handbrake cable for a Hillman Minx - went in with the broken one and they made an exact replica for only a few pounds .

 

[w123ce280]

Derek

Thank you for going to so much detail in your reply, there are a couple of cars up the country that I believe still have most of their parts. The chap I bought the car from has at least three that I could see. Failing that I am in the Marine Engineering business myself so I could make a few enquiries regarding making up a cable.

By the way the W126 would have been my first choice it's in my opinion one of the very best designs, quite literally a different class of car. My Garage just isn’t long enough!

Again thank you for your time.

Regards

Brendan

 

[219]

A W126 is basically just a slightly bigger W123 - many components are shared between the two models and the engineering is very similar .

 

[cooks]

is the lining easy to remove as im having problems with the sliding of the roof..and did you have any other pictures on undoing the lining and sunroof,any advice would help.

 

[ianrandom]

Yep the lining has pop studs at the front. You have to have the roof half open, pop the front studs, then slide the lining out and upwards.

Derek, thanks for the info earlier in this thread, I changed my cable and motor and all was well.

Sunroofs need regular lube with the special white MB grease. It might be that you need to remove your slide rails (As seen from above the roof when it is opened, just the three phillips crews each side, but dont touch that one at the front which is for adjustment of how flush the panel sits.) Then you can degrease the rails and grease them with the proper stuff. If this doesn't get done the roof will end up breaking and potentially being loads of hassle.
What are your symptoms with the sunroof?