Cab Rearview mirror stains

My guess is these stains are from moisture/hi humidity.


Before me, this Tundra spent its 1st 18yrs in Central Vly, CA...farm country; basically hotter than it is wet.
Both my cab roof/windshield joint are solid; no rust, just flaking clearcoat.
Inside cab same; no water stains or discolored headliner- all dry and solid.
Is it a known production QC issue w/toyota cab mirrors?
Or is it likely moisture/humidity/heat inevitable effects over 18 yrs?

Typically seen this on Detroit era 'resto-mod' cars, and in those, it was apparently due to moisture from rain runoff into cab from windhield/roof joint corrosion.

 

Moisture and humidity can do that. Maybe sun combined with cowl fastener leak? Any signs of mildew (dark spots on rubbers/plastics/seat belts)?

My '06 wasn't exactly perfect around the edges either, but nowhere near that bad. The image wasn't exactly clear either, it wasn't really crisp. It was my motivation to replace the mirror. You're welcome to my old one if you want it (assuming I can find it).

I needed Homelink garage door opener on my mirror, so I installed Toyota p/n PT374-00210 which was a direct swap, and doesn't require wiring to have a garage door opener in the mirror.

 

@shifty, thanks but Im heading the same direction for an updated [compass/temp] mirror, likely a Gentex you all have posted about here.

Will be doing some more inspection for leak spot evidence, but meanwhile, having scanned the leak threads posted, floors and backwall of cab look dry and clean as a 'day-one' Tundra [that would be my inner optomist speaking].
Im sure Ive got few [clogged rear wi dow channels], I just havent yet witnessed them. Browsing the 'window leaks' results came up w/a guy who posted here or maybe Utube, on finding and fixing on his FGTundra- was about a 30min tour and covered just about EVERY opening of the entire cab.
Meanwhile, heres a shot of my cab roof/windshield seam. Except for the flaky clearcoat, it looks intact.

Sorry about strike-thru of text. Cant find the 'strike-thru' button to save my life.....maddening!

 

Strikethru is in a weird spot, the "insert" menu (see below).

Your clearcoat is clearly failing, but there's a solid chance it's still intact at the windshield seal. I would expect you'd see staining of the headliner if you were leaking there. Is that the original windshield? (i.e. is there a Toyota logo in the driver bottom corner, or another company?)

RE: Leaks ... the video showing all the links, I think there's a link to that video in the Definitive Leak Thread, which is in the sticky section.

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thanks again shifty.
Rarely used 'Strike-thru', well hidden, except for inadvertant double taps.

yes! OE Windshield...

 

Take care of your OE windshield! I miss mine.

My original weatherstripping on the top of my windshield looked a lot worse than that before it was replaced. For a while it was actually missing, and it still never leaked. Based on the fact that your truck is from cali, and you don't notice any water intrusion evidence, I'd be skeptical of a water leak being the source. Just my $0.02.

 

I also doubt water leak. I had this happen to a couple of cars in the sunshine state. And again, my corner was starting to show signs it was beginning on my original stocker mirror (which I still have, somewhere, if anyone wants it).

Perfect time to upgrade. Modern mirrors degrade in quality over time. My mirror had a weird fuzziness, almost a minute double exposure when I looked at it, it drove me slightly nuts.