2007 S550 Sport w/ Pano Roof:
A week ago I went to open the roof, the sun shade opened but made a ratcheting sound when it went fully open.
Sounds like the gear may have stripped, but the shade opens all the way and closes all the way, however the roof open switch must not be tripped\satisfied that the screen is all the way open because the roof won't open. I believe the roof would function properly except it doesn't think the screen is opened all the way.
The ratcheting sound is in the front of the screen, if the roof access panel comes off then I'd consider attempting that but I have no idea where to start.
Anybody have any experience with this? Is there easy access to this or am I doomed to a pocket-draining experience at my local MB Service center?
TIA, Sal

 

Must not be a very common problem.

 

Yeah, the motor assembly is shot. Some say the bracket gets bent and may have success bending it back. Replacement involves yanking down mirror assembly and the headliner a tad.

$1,000 at dealer for me. I found it funny it was a Webasto part. Who's sunroof motors go into every car under the sun. No pun intended. Really.

 

Argh, thanks for the info. Between that and my steering column tilt motor I'm looking to drop $2k at the service department, again.
If these cars weren't so dang smooth, comfy and quiet the additional costs could really become annoying.

 

I wish at the time I explored the indy shops more carefully to see what they would charge but the car was under extended warranty so eh...

 

Unfortunately it is more common than it should be. Depending on how comfortable you are with performing your own service, you can likely repair it yourself.

There are two motors in front of the pano roof above the sunvisors. The one on the left when sitting in the vehicle is responsible for moving the glass, and the one on the right is responsible for moving the front shade. Unfortunately, one of the maintenance items that is commonly overlooked is lubricating the sunroof. This is outlined in the factory service schedule and is done when a vehicle is taken in for service at the dealer, however most DIY owners do not think of it. The lubricant is very slick and is specifically for the sunroof guides and rails and rubber components. As the pano roofs are entirely made of glass, after some age and excessive heat beaming down from the sun the lubricant dries up and the motor must work harder to move the glass. When this happens, typically the issue is the motor's housing manufactured from a soft metal is deformed due to the excess torque the electric motor must use to move the glass. Over time, this metal stretches and allows the gear that drives the sunroof cables (there is a single gear and two threaded cables that contact each side of the gear; one side is pulling the left side of the glass and the other side is pulling the right side of the glass. When the housing stretches, it allows the gear that drives these cables to raise and lower out of tolerance for it to work effectively, slipping against the cables that are supposed to move the glass. Due to the glass, in most cases, not serviced with the appropriate lubricant regularly, it is difficult to move so the motor just begins to slip causing the noise you are hearing. When you hear this noise, do not attempt to move the glass electrically as it will only cause damage to the motor and possibly the sunroof assembly in that the glass rides on.

To repair it, assuming it has not been operated excessively in this condition, is to drop the front of the headliner and the motor is held in by three Torx screws. Remove the rear view mirror by pulling it downward with force and it will release from the mount. You will need to disconnect the wires for the microphones and photocell that operates the auto-dimming feature. Remove the grab handles on the passenger and driver side by lowering the handle and using a thin trim removal tool to ensure the plastic is not damaged, open the covers on each side of those handles to reveal the torx screws holding them in and remove them. There are covers that also hold the sunvisor arm and snap-in assembly opposite of the arm that need to be removed.

Remove the plastic AIRBAG covers on the A pillar to remove a nut holding these in place on each side, and remove the nut and carefully remove the A pillar. You will also need to remove the door seal by simply pulling it away from the vehicle as it is held on with tension.

Remove the B pillar AIRBAG cover and remove the nut from each side to allow the B pillar to be released. After the nut is removed, there are metal clips that hold it on.

Open the compartment that holds sunglasses and you will see two plastic Philips head screws. Rotate these 1/4 turn to drop the upper control panel. You will need to carefully remove the wiring the is connected to the upper control panel, noting how the are arranged. They will only go in one way, but since you cannot see the connection it can be challenging the first time to connect them back when it is time to reassemble.

There are additional metal clips that hold the headliner in place where the opening for the glass is, so gently pull down where the opening in the headliner is for the sunroof and tug down and it will release, being careful not to lower it too much. If you have an S600, you will have the Alcantara headliner with a fiberglass backing, so you want to bend this as little as possible. You can raise the seat and the headrest to prevent it from dropping too far. This will clearly expose the motor. If you reconnect the overhead control panel with the sunroof switch, you can attempt to briefly operate it and see exactly what it is doing.

In some cases, the three torx bolts that hold the motor in place have rubber bushings that dry out and flex too much causing it to slip. In other cases, you can view Allen screw where the emergency closing tool inserts and see it raise and lower as you operate the motor. If you see it doing this, removing the motor, placing it in a vise and re-shaping the housing by applying pressure can fix it, as can applying washers around the Allen screw is exposed inside the case.

Or, assuming the cables have not been damaged, you could purchase a new motor for ~$250 and install it and fix the problem which comes with new screws and rubber bushings for the screws.

It sounds like a lot of work but it is not very difficult.

A quick search on YouTube for "repair panoramic sunroof" will show you this is not a Mercedes-Benz-only issue, but is common among many manufacturers.

Review this video for some insight of the process. I do not know this person, but his video is helpful and can be very useful if you decide to perform the task yourself:

.

 

Thank you very much, that was very thorough and helpful. I believe I will tackle this job myself.
The ratcheting sound I heard was from the sunshade only. It was at that point that the roof wouldn't open. Up until that point the roof opened and closed without issue.
Since the roof won't open unless the sunshade is fully opened there must be a limit switch that isn't getting depressed anymore.
The ratcheting sound I heard was definitely coming from the right side of the roof, where as you described, the shade motor is located.
I own Italian motorcycles and have done lots of wrenching over the years on them so this doesn't scare me at all. I just didn't know where to start to lower the head liner.
Thanks again!
Sal

 

You are pretty much right on. The electric motors are interchangeable and are the same part numbers. You would just need to evaluate how it is behaving and adjust accordingly and you should be good and keep some money in your wallet!

 

Found this vid on where to lubricate the panels and the type of grease to use.


Thanks again PB!

 

Great. Sounds like you have a handle on this. Failure of the pano roof It is fortunately something that can be prevented if the suggested maintenance is performed.

Also, remember to remove the mesh plastic cover that is located on the passenger side for the intake of the HVAC and ensure it is free of debris. These will clog the the drains that are located underneath the vehicle where the A/C evaporator drains, and will cause water to build up inside the HVAC enclosure. When it accumulates so much, it reaches the level of where the system pulls the air into the interior of the vehicle, spilling over and possibly damaging the HVAC blower assembly and regulator on the passenger side. Just include checking this during your regular maintenance.

 

Follow Up! I followed Polar Bears instruction and a couple of YouTube videos last Sunday and got this fixed.
I have a couple of notes I'd like to share since it's still fresh in my mind.
Once the headliner is lowered I'd take some masking tape and lay it across the plastic inserts that locate the driver and passenger Sun Visor\Shades. Not the clip retention side but the actual swivel end that goes up inside the head liner.
With the 2 attach screws removed the inserts above the headliner are free to roam wherever they like, so take a second and tape them in place.

I dropped by ACE Hardware on the way home from work last Friday and picked up a bunch of nylon washers.
The shoulder bolt diameter for the 3 screws that hold down the electric motors is .276", that's 7mm. I guessed and picked up 5/16 ID washers figuring the OEM bolts wouldn't be under 1/4".
IIRC the face thickness of the OEM washers was about .039 (1mm). I grabbed washers that were .084 thick. As well as a bunch of other ID's and thickness's.
The problem is the rubber grommets isolate the bolt shaft but also provide insulation for the upper and lower flange face. The lowers get distorted from the weight, heat and vibration.
The bolt shoulder interferes with the threaded hole, ie, tightening them down all the way will still leave the motors loose.
So replacing with a thicker washer allows you to retain the original grommets.
Also I did one bolt at a time and didn't have to mess with removing the motors and I didn't remove the B-Pillar post covers as I had enough room to get my arms up inside of the headliner, being careful not to put any downward pressure on the hanging headliner. This also meant that I didn't have to drop the console much and was able to leave all the electrical plugged in.
I replaced the nylon washers on both motors since I was in there, lubed the rails with synthetic grease and now it works as it should.
Changing the Cabin Air Filters tonight.
Thanks to Polar Bear and his timely advice!

Sal_Monella

 

Thank you for posting your follow-up! It will certainly be of her for users searching for this!

 

08 S550 Pano off track & stuck in semi tilt position. Though familiar with headliner replacement S550 Pano is a different beast ($$$$$$$$$$).

So, THANK YOU for the guidance which I need so badly. My comfort level is raised & my blood pressure is lowered 😄😄😄!

Much appreciated My Man

 

These forums make DIY not such a murky deal sometimes.
Like PB said, Be sure to clean the rails and reapply synthetic grease and you should be golden.

 

reupping this old post. i am helping my father with his W221 S class. the motor in the sunroof started doing the skipping and bad noise recently. he tried opening it (against my advice) and it got stuck about 2-3" from closing. we ratcheted it closed for the time being and ordered a new motor.

installed the new motor while the sunroof was closed (keep in mind we ratcheted it to this position, not sure if that matters). opened right up and glides very nicely. problem is, it will no longer close fully and seems to get "stuck" a similar distance as it was previously. not sure if related, but a bit coincidental. i noticed that it's slightly "out of whack" and the driver's side is like 3/8" or so "ahead" of the passenger's side.

we removed the glass to see if we could figure out what was happening with the mechanism and if it would close without the glass on there, which it still won't. so suspicious of a mechanical/physical limit being hit prematurely. any suggestions welcome...

the right arm comes up a bit slower than the left side (with and without the glass installed)

this is as far as it will close, then it stops and the shade closes. so it seems to "think" that the glass has shut