Hi, I have a 2012 GL 450 I noticed that the rear sun roof has discolored and is not looking clear anymore. Is there anything I can do or this is just normal due to aging?

 

I think @Max Blast looked into it. Practically speaking, there is nothing you can do short of peeling it off and replacing it.

I seem to remember being tempted to paint it, so the UV damage did not penetrate any further. I'm pretty sure it is Lexan (polycarbonate), which does not last forever in the sun.

 

It is lexan or polycarbonate, and will start showing hairline fissures ant this age.

and I tried canopy polish to smooth out the hairline cracks - With no effect. If not cracked or leaking leave it tf alone.

if cracked best you can do is scab on a large sheet of vinyl to protect from water getting in or around it.

 

Ah yes. Thank you for the refresher.

I have used polycarbonate roofing panels on patio covers. In a couple of years it turns whitish when looking from underneath. The UV protective layer comes off and then the panel starts decaying. How long will it last? There is an absurd number of variables.

Polycarbonate can be painted, but it has to be done with solvent free paint, or the surface will be softened. The question then is, how long will the paint layer last? It is like the headlight polishing kits: They make the surface look great, but the protective layer does not last forever. At least with an opaque layer, the pigment can block UV.

https://www.justpolycarbonate.com/po...-7-expert-tips

 

I do believe there is this entire subset of the RV industry devoted to this problem statement.

 

My 2010 GL450 developed a hairline crack in the in the front of the "glass" and then continued to develop a leak which found its way to the rear of the vehicle. $1,600 just for the part as I refused to replace it with salvage glass as who knows what that part has been through.
Right around 10 years and I've had the pano glass crack, the rear taillight gaskets and now even the third (high) brake light cracking and leaking!

 

I have previously mentioned this in other posts... but I still haven't done anything about it

There is some type of clear (tinted?) vinyl over the actual sunroof. I "believe" that's the part that is the problem. My thought is that gentle use of a heat gun and a plastic scraper should get the protective covering off. Then I can reapply a protective/UV-resistant clear vinyl. 3M - and others - make stick-on coverings for house roof sunlights - I'm pretty sure there are exterior rated ones.

 

It is a bit cruel that a "gelandewagen" fares best when it is kept out of the sun and rain.

My neighbor has a vintage Toyota Landcruiser. It was in his father's barn for thirty years. They filled it with gas, changed the oil, and it started right up.

All that aside, I wonder how well the adhesive sheets would hold. The RV guys probably have figured out something for this by now.

 

I think it would work well - I mean, that's what's on there now - so anything "quality" should do AT LEAST as good? Probably better.....

 

I don't think what is (was!) on there was an adhesive sheet. I think it was a coating. An adhesive sheet would be ridiculously expensive to apply.

The coating may have been similar in composition to a vinyl sheet, of course.

 

There's a definite edge around the perimeter like an adhesive sheet would have. But I suppose that could be where the masking for the coating was. But if it was a coating... wouldn't it make sense that it would cover the entire piece of glass and not have an "edge"?

 

I think it is just masking. I don't feel a lip like I would expect from an adhesive sheet. I think the "glass" is formed and then the coating is applied.