W124 Sunroof problems

[MW]

1992 W124 230E salon.
About every 2 years the sunroof plays up and will not open or tilt. Sometimes it is associated with the windows playing up, but not this time. Strangely it often occurs in warm weather. Then after about 2 weeks it often fixes itself.
This time there is sometimes a clicking/soft clunking noise from somewhere near the rear left passenger bodywork, maybe even from the rear roof area. The noise is also a cycling sound as if a motor is slowly moving over a 20-30 second time period.
Any ideas?

 

[wireman]

You sun roof motor is in the LHS of the boot. This is your noise source. I am not sure why it runs for 20-30 secs,it is only powered when the roof mounted switch is actuated.
However a brief desciption of what you have may be in order.
A stiff cable (looks like a chunk of bike brake cable with small barrels threaded along its length) passes round a motor driven plastic winding wheel with odd shaped teeth that engage the barrels on the cable and push the roof closed or pull it open. There is also rotary switch driven by the cable that stops the motor as it closes from tilt or slide, there is a small knob on this which is used to syncronise the motor stop position with the roof position.
It is not unknown for the plastic winding wheel to wear out and give intermittent operation or just not close the roof at all. The part is expensive.
In the boot, LHS forward corner there is a 17mm hexagonal plastic stud which drives the cable manually, try moving the roof with this if you dare.
If you get a torch mirror and your head in the corner you may be able to find something loose or not right looking about the motor unit, but beware of taking any bits off, the sunroof is horrendously time consuming to service.
Unless you are prepared to shell out lots of time or cash for somebody elses time leave it closed and take the fuse out of the sunroof circuit.
Details of the manual proceedure and fuse location are in the owners book.

 

[MW]

Mant thanks. Since then, an update.
Yesterday the windows which were OK, started playing up. Passengers window when down, would not go up. Switch off engine, window now goes up and all is OK.
Sunroof worked once normally, and was then back to this 'odd state'. Before the trouble the roof was normal, with no hint of a problem.

 

[Hibbo]

Replace all your fuses and clean all the fuse holder contacts. Works wonders!

PS. Although wireman is correct about the sunroof being v difficult to service, this is not true of the motor mechanism which is easy to replace. It's when your cable goes that you're in trouble!

 

[Mr Teddy Bear]

I had problems with the sunroof on a 1994 Corrado where it failed partialy
open, this was a linkage problem. the repair bill was over £300.00
This is 4 or 5 years ago. Repairing sunroofs is a specialised field hence a
cornered market. I believe there is only company here in Brissle.

Tim

 

[Hibbo]

Get a new motor.

There is a pishy nylon cog in there that wears.

 

[frank133]

sunroof

Hi wish you luck with your sunroof,I did hear on one forum a charge of over 600 quid to repair a sunroof,at a mercedes dealer,As stated it is a bit of a time consuming job,the first one I had to do was just replace a cable in my 190e,a few years ago.But recently when it started playing up again,I changed it for a manual sunroof.Wasnt happy with it so changed it again for a electric tilt and slide,I think the hardest part is getting to the problem,if in the headling it,takes time to remove the headlining,I do not think its a specialists job as it says in the haynes manual,After all the only tools you need are a Philips screwdriver and two small sockets.[with global warming continuing at such a alarming rate].Sunroof technicians will soon be able to charge as much as plumbers:idea:

 

[MW]

Pretty sure it is electrical. Yesterday I tried it with the door open but the ignition off. Worked perfectly as normal. Smooth with tilt and opening function. Closed as normal. Started engine and drove off, and its not working again with ignition on or off, or doors open.
Must investigate fuse box.
Are there any relays here with potentially poor contacts?

 

[Bolide]

There's a relay hung behind the motor. If it fails the roof stops working. I'd start there. There are two types dependent, I suspect, on model year

Also check there are volts avalable at the motor when the system fails

Nick Froome
www.w124.co.uk

 

[Mat_b]

hi, had same thing with mine, its one of the fuses that powers the relay when ignition is on, its not marked up as windows, may have been the wiper one, take out each fuse and inspect the ends, they wear through, maybe letting just enough current through for one thing and not another!

 

[Hibbo]

Replace all your fuses and clean all the fuse holder contacts. Works wonders!

Trust me!

Best £3 I ever spent!

 

[bigasotonuk]

Hi,
If your sunroof works ok with the door open there is nothing wrong with it as Mercs have a courtesy system which allows windows and sunroof to operate with a front door(s) open you will have a relay/fuse problem as Hibbo has said.
My bet it will be relay with dirty contacts.

 

[turnipsock]

Trust me!

Best £3 I ever spent!

There is a relay in the boot near the motor, it's a plug in thing. Clean the pins on this...it was the source of my problem.