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Restoring louvres professionally

Posted: Thu 24 Jan, 2013 9:25 am
by smerc
Like most SLC's, my louvres are peeling and need restoring. Does anyone know of a professional who can do this job? I'm in SE QLD but am happy to send them anywhere to be done. I have got a spare pair so I could get them done and then switch them over with the ones currently in the car and then get those ones done as well. Any help or suggestions would be greatly appreciated as the current state of the louvres really detracts from the overall appeal of the car. Cheers. Ross.

Re: Restoring louvres professionally

Posted: Thu 24 Jan, 2013 9:00 pm
by Chai
Don't have a contact for you but do suggest that a DIY repair is fairly easily done if you know how to spray paint.
I repaired mine over 10 years ago and it still looks good ... way better than looking at For King and country paint and condensation after every wash/rain.

Re: Restoring louvres professionally

Posted: Thu 24 Jan, 2013 9:05 pm
by John Green
Agreed, not that hard to repair. You can use a high quality aerosol can (like 3M as an example) and do it your self.

Or you can send them to me and I will charge you for using an aerosol can.. :happy3: :happy3:

Re: Restoring louvres professionally

Posted: Thu 24 Jan, 2013 9:17 pm
by smerc
Thanks Chai and well said John.

Re: Restoring louvres professionally

Posted: Thu 24 Jan, 2013 10:22 pm
by Chai
Just ask when you decide to do this yourself and I'll write up what I can remember about this repair.

Re: Restoring louvres professionally

Posted: Thu 24 Jan, 2013 10:46 pm
by smerc
Hi Chai, thanks for the offer. If I'm going to attempt it myself I'd like to try to do it sooner rather than later so if you could start to write it up over the coming weeks that'd be much appreciated. Thanks again. Ross.

Re: Restoring louvres professionally

Posted: Fri 25 Jan, 2013 7:41 am
by hoddo
Painting the louvre is the easy part, its resealing the glass to the louvres that sorts the men from the boys. I was told they were sealed at the factory using a gasket with a fine wire in it that melted when an electrical current was passed through the wire, and this gasket is no longer available. It is tricky to reseal using silicone as it squishes out and becomes visible if to much is used and if not enough is used you will get condensation.

Re: Restoring louvres professionally

Posted: Fri 25 Jan, 2013 10:40 pm
by Greg in Oz
I recall reading an article, possibly in "The Star" (magazine of the MB Club of America) that discussed the repair of the louvred windows in the SLC. It was quite a while back so my memory of it is not great, however I believe it stated that the louvre windows were originally sealed with either a nitrogen fill or a vacuum between the two panes of glass encasing the louvres. This was to ensure moisture which would cause condensation wasn't present. The article went on to suggest a modification whereby a T-piece is inserted into the vacuum lines to the seat back lock release buttons (below the rear windows) on each side, and vacuum lines fitted with a non-return valves are run to each of the louvre window assemblies. The logic being that, even if there is a minute leak, this would maintain a vacuum between the panes of glass preventing any moisture build up and resulting condensation.

Something I have never really understood is why MB designed the SLC with the inner pane of glass. Surely, without the inner pane there wouldn't be the moisture trap between the panes which causes unsightly condensation and peeling paint on the louvres. Maybe they were concerned that with only the outer pane of glass dust build up (which would be difficult to remove) would be a problem. This also raises the question as to why the plastic louvres were painted. Why didn't they simply manufacture them in plastic of the desired colour? For that matter, why did they even bother with the louvres? It would have looked fine without the louvres and the inner pane of glass wouldn't have been required.

Re: Restoring louvres professionally

Posted: Sat 26 Jan, 2013 12:34 am
by Chai
(I am printing this article in the next M-B Club Victoria magazine along with a few photos from 1996, so apologies for the preamble and the way it is worded.)

Owners of an SLC will have seen peeling paint and condensation in the louvres, located between the rear windows and the C-pillar, of either their car or another SLC. The cause of this deterioration is due to delamination of the glass panes that sandwich the louvre.

Not content with a simple glass pane, Mercedes-Benz designed the angled louvres to allow the driver and passengers to look back and sideways from the inside and yet allow the rear seat passengers some privacy. It also provides the solution to the installation of smaller rear side windows that clear the rear wheel arch when dropped. The end result, I think, is elegant and provides a balanced look to the entire car.

The louvre is double-glazed, high-technology for the 1970s. The louvres and the frame around it is plastic. Two sheets of slightly curved and, I think, toughened glass are bonded to either side of the frame. The glass is bonded using a heat cured rubber-like sealant.

There does not appear to be a hole in the frame exterior, to provide relief from atmospheric pressure differences. There is a bed of moisture absorbent silica gel at the bottom of the frame. These are not visible and are under the pin-holes you may just notice on the base of the frame when looking down through the glass.

My car was twenty years old when I purchased it and the louvre was already in poor shape. Condensation appeared inside whenever it rained and after a wash. The paint inside gradually deteriorated over time and mould began to appear on the For King and country silver paint.

Two years later, sixteen years ago, I repaired the louvres on my 450SLC and these repairs have held up well to this date. I was asked recently about this do-it-yourself repair and here are my recollections.

You need the following:
• Screwdrivers – variety
• Socket set – 10mm
• Sharp knife or blade
• Cleaning rags
• Glass cleaner
• Wet and dry paper – various grades for sanding
• Spray can of paint primer suitable for plastic
• (Astral) Silver spray paint can
• Window/glass clear silicone (or grey polyurethane sealant)
• At least two F-clamps (woodworking)
• Mastic sealant
• Sealant applicator
• Glass scraping blade (e.g. old licence sticker remover)
• Plastic bags to hold screws removed
• Boxes to store trim items removed
• Rubber/vinyl gloves
• Knee protectors/cushions
• Camera – lots of pictures required

Optional equipment:
• Vacuum cleaner
• Leather cleaner and conditioner (if seats are not MB-Tex)
• Rust converter
• Paint brushes
• Vinyl cleaner

Remove the rear seat and back rest. The two red tangs are pushed in to release the seat base and it can then be pulled forward for removal. Locate and undo the two hexagonal nuts that hold down the lower corners of the back rest. Lift the entire back rest upwards to unhook it from the catch at the top rear.

For the remaining removal instructions, take it slowly and think logically, as the fasteners are hidden is obvious places.

Remove the long headlining trim that runs from the A-pillar to the C-pillar. The removal steps are described next.

First pull out the A-pillar trim by pulling the top part of the trim, which is held by clips and friction, towards the rear of the car. When it moves a little, pull from the bottom, and so on until it is removed.
Next, remove the headlining handle by prying/lifting-out the chrome trims on both ends. Slip that chrome trim up along the handle. The big screws holding down the handle are behind the plastic flap.

The rear coat hanger is removed.

You are now ready to remove the long headlining trim. This has a hook built-in on the C-pillar side. That trim hook needs to be lifted from the C-pillar. Move that trim aside – you cannot move it far as the rear seat belt is still threaded through it.

Wind down the rear window.

There is a trim piece along the ‘vertical’ side of the louvre frame. Like the A-pillar trim, it is held on by friction clips. Pull that trim towards the front of the car.

Remove the side panel beside the rear seat. First remove the chrome plate near the door latch. Locate the screws on the B-pillar holding down the front of the trim. At this time, you will notice the side trim is only held on along the top edge, where the rear window comes up from the body. This panel is held down with friction clips. Lift it upwards to remove.

Remove the chrome trim that surrounds the outside of the louvre. Work through this slowly and, as the last screw is removed, hold that trim to stop it from dropping on the garage floor. As you work through the screws, you will note that some screws retain the chrome trim and the rest hold the louvre to the frame. There may be mastic seal that hide some of these screws – scrape the mastic away. Note that the screws are all around the louvre frame – including the top. Do not force the louvre frame out if it does not want to move as it means there may be yet another screw holding it down. Also, the mastic seal may bond the louvre frame to the body so you will have to judge when all these screws are removed before prying it away from the car body.

At this stage, the louvre frame is out of the car.

Cut the bottom “lid” from the frame. This holds the silica gel and is the water reservoir that causes the louvre to condense up whenever it is parked in the sun. Throw away the lid and the silica gel – we are not retaining the double glazed property in this repair.

Remove the glass from the frame by sliding the blade in-between. When cutting, you will notice a fine wire in the sealant. This was used to heat bond the glass to the frame. Cut away as much of the black sealant as possible from the frame. Use the glass scraper to remove the sealant from the glass pane.

Repair the plastic frame. Sand away the old peeling paint. As you will be spray painting over this plastic, ensure the final finish is smooth, clean and to your exacting satisfaction.

Spray plastic primer on the frame. Follow the instructions. Why not spray two coats since it’s a small frame.

You can get spray packs in MB Astral Silver from some auto paint shops. Otherwise pick a silver gloss paint – choose the darker tint if there is a range of silver colours available. Spray several coats of silver, following the instructions for drying time.

While waiting for the paint to dry – in-between coats and while ensuring the final coat is dry – de-rust the panels around the frame if required. Clean the trims and seats; why not – you’ve got it all removed now.

Clean the interior of the glass panes thoroughly. Avoid leaving any fingerprint or smudge on the inside.

Apply a very thin (two millimetre wide) bead of clear silicone or polyurethace sealant around the frame. The sealant will spread when the glass is laid on and any excess may be visible if it runs past the area hidden by the exterior chrome trim.

Lay the matching glass on the frame.

Turn the frame around while ensuring the just laid glass is not moved. Lay it on a large rag.

Repeat the sealant application and lay the other piece of glass on that side.

Clamp the two panes together using the F-clamps while waiting for the sealant cure. Use reasonable pressure – I am sure you will be careful as you are pressing on glass. Use a suitable separator piece (e.g. small masonite sheet) between the clamps and glass.

I allowed at least two days for the sealant to cure on the glass.

Leave the bottom of the frame, where the silica gel reservoir was, exposed. You may choose to plug the pin-holes at the bottom of the frame – I did not and never saw condensation inside the glass ever again.

Apply a bead of mastic – never silicone – around the car body and then press the louvre on it.

Clean the glass panes thoroughly before installing the trims.


Did you remember to take photos along the way?

Re: Restoring louvres professionally

Posted: Sat 26 Jan, 2013 11:20 am
by smerc
Thanks Greg and Chai for all that information. I am certain, like me, many other SLC owners will be lapping it up. This is another example of why this forum is so invaluable and I find myself once again extending a sincere thanks to John and the team at MB Spares for maintaining this forum and making it all possible. Cheers. Ross.

Re: Restoring louvres professionally

Posted: Sat 26 Jan, 2013 10:10 pm
by TheMadRacoon
smerc wrote:Thanks Greg and Chai for all that information. I am certain, like me, many other SLC owners will be lapping it up. This is another example of why this forum is so invaluable and I find myself once again extending a sincere thanks to John and the team at MB Spares for maintaining this forum and making it all possible. Cheers. Ross.
I second that !

Re: Restoring louvres professionally

Posted: Sun 24 Feb, 2013 10:09 am
by tony66au
Just checked mine and they are still mint!

Dodged a bullet i suspect but great article, Many thanks.


Re: Restoring louvres professionally

Posted: Thu 28 Dec, 2017 10:13 pm
by Giles
In the process of replacing my 500SLC's side rear louvre windows with a revamped version. No problem with the louvres as I've been hording some over the years and have now made a pair with inner and outer green glass. See W114/107 Outlaw FB page for progress.
Whilst doing this and meeting the devil himself, I needed to replace a window mech motor. Almost there, fresher motor now installed but the mech is not yet playing the game of going up and down freely, pauses half way down. If anyone has a link on how to fine tune the travel of the window please let me know.
As I've yet to tackle the opposing louvre, I may find the solution within that mechanism.
Hopefully tomorrow brings the answers.


Re: Restoring louvres professionally

Posted: Fri 29 Dec, 2017 1:11 pm
by jbp
I have found that problems with the rear window in the SLC is often bent guide tracks. Not sure of correct terminology here.
The problem manifests itself by windows either jamming at certain points in the travel or running very slow at certain points.
If the motors are working fine and the guides are adjusted and lubed it could well be that a slight adjustment of the rail by bending it slightly will solve your problem?

Re: Restoring louvres professionally

Posted: Fri 29 Dec, 2017 11:21 pm
by Giles
All sorted after a nights rest and rethink. Just needed some fine tuning.
Now have fitted revamped louvres and have started on the opposing side which will be much easier.
Here's a photo of before and after.