Sun is shining and the car has been standing all day in the heat, you open the door and when the extreme desert heat punches you in the face like a big angry and scorching red Finnish man of a beast who just has been sitting 30 minutes in the sauna. You might starting to have seconds thoughts about driving when your car is nearing 80°C inside. Anyway you man up and get in the car because you actually have to go some places and do stuff. What other thing could be more annoying than a stuck sunroof so you can cool down (I’m assuming your air conditioner is not working)?
Maintenance of the sunroof mechanism is to prevent such scenarios and also keep the sunroof motor from getting destroyed, of if you have a manual sunroof, then the handle can actually break off. Then you would be sitting there and sweating your ass off. Imagine the opposite case, where you can’t close it and it rains!
There is one way to prevent this situations for happening, clean and grease those sunroof tracks!
I will only cover the manual sunroof here, the only difference from the electric one is a cable which you have to extract, and that is quite messy.
On this particular demonstration car, a 300TD wagon with a manual sunroof, it was a pain to open and it ended up never being used. So I finally got myself to unbolt the sunroof and properly clean those tracks and glide feet of the roof. Then lubricating it with some special Mercedes sunroof grease before putting it all together. The process is quite easy, however you have to be careful not to damage the inner sunroof lining or chip the paintwork when you take it out.
So you need special purpose sunroof grease from Mercedes, I really mean this, it will last 15 years and can withstand the rain. I got mine from mercedessource.com where they sell kits to do this job, you can also go to a dealer which is probably more expensive.
No special tools are needed.
Unscrew those two side plates when your sunroof is open, 8 philips screws in total. Let the flat head screw be there, it’s just for adjusting.
Unscrew the decorative plate for the handle, keep in mind that it’s made of plastic so it can break easily. Especially since it’s old and brittle. You can not remove the cover so you have to push it carefully through the head lining, since the head lining is coming off in the next step.
The head lining is held up by some metal clips in the metal of the sunroof, just grab the front end of the lining and pull down until the metal clips are free, taking care the plastic cover comes through the hole at the same time.
Remove the head liner by pulling it out while the sunroof is open.
Then unbolt two 8mm bolts as seen on the picture under, same on both sides, these hold down a plate which holds a crossbar, keeping the sunroof attached to its’ rail.
The Sunroof can now be taken out, take great care of not scratching the paint of the sunroof or the body of the car while taking it out. Get help from someone if you find it difficult although it’s not very heavy.
Start by removing the old grease on the plastic glider feet pads on the sunroof and the guiding rail on the car. If the plastic feet are broken, then you might have a hard time getting replacements, this is why preventative maintenance is the best maintenance. Sure you will be thinking I’m a smartass…
Grease all 4 white plastic feet, don’t grease the black pads made of cloth.
Again it is important that you grease the tracks and rails with Mercedes special sun roof grease, this is to do with the engineered properties the grease has to resist water from the drains and still provide lubrication without flushing away, and it’s very long lasting. I think this is the first time the sunroof has been greased on this particular car since it was new, 28 years ago.
Clean the rails and grease the other side of the the top edge that the screw holes are. Note the position of the plastic feet and the cloth pads. Only grease the rail where the plastic feet are touching and not the cloth, or you will have a sticky sunroof.
Once cleaned and greased up in the right places, you could assemble the sunroof reverse of removal.
Feel how easy the sunroof slides compared to before, it should slide effortlessly back and forth.