Sunrooof rust bubbles

[n3nyongmini]

On E30's, are the typical sunroof rust bubbles caused by rust forming at the top, under the finish paint, or by rust coming through from underneath?

IOW, should I 'pop' the bubbles, clean, prime and touch-up the paint, or will I be faced with a small hole clean through the sunroof panel? The two bubbles are about 5mm across at this point and don't seem to be growing, but I see 'em every time I get in my car...

The car has been in San Antonio for all of it's life/owners (as best CarFax will tell me), so no current, constant contact with road or oceanic salt.

Thanks - this site is da bomb.

Derek

[Apex381]

My car was a California car most of its life and yet its still rusting on the sunroof panel like yours is. Mine is definitely rusting from the underside up and whenever I open the sunroof rust sifts down into my car like a light snow! I think our best bet would be to just get a new sunroof panel.

[mtechnik]

I have a small spot prolly round 3/4 inch in diameter & thankfully hasn't increased in size since I bough the car 3 yrs ago. This with wet winter seasons

[Dex.e30]

IOW, should I 'pop' the bubbles, clean, prime and touch-up the paint, or will I be faced with a small hole clean through the sunroof panel? The two bubbles are about 5mm across at this point and don't seem to be growing, but I see 'em every time I get in my car...

I also have a few minor rust spots, and was curious about how to mange them. Repaint won’t be until next year likely.

[adept]

I usually try not to bother with them. Sucks, but I have a small spot on my sunroof as well.

[rede30]

yea unless you are going to paint the whole panel dont worry about it. After saying that, it wouldnt be that big of a deal to have the sunroof painted. You could just have a few other things painted at the same time: lips, mirrors, bumpers, whatever you have just to make it worth your time to deal with a paint shop. Also you can search around for used sunroofs that are the same color as yours. I have a mint blue one that i would love to sell to someone who needs it.

[MikeE30325i]

damn, i am lucky and only have rust on the rear valance right above the muffler tip.

but dont worry about the rust unless you plan on painting the whole panel.

[BDSax]

when the sunroof starts to rust, its fucked. it starts rusting the metal seems inside and its not worth it to fix. i found a good panel at the junkyard ($30) and got this stuff from eastwood called Rust Encapsulator. I soaked the hell out of the inside of the panel where the metal seems together to help prevent rust. other then that i would suggest keeping your drian holes clean.

[IDontLikeYou]

Although already pretty much answered, ours is from the inside out. The front lip is almost completely deteriorated inside (driver's side corner), and only bubbles on the outside. A new (or better used) one is on the list of things to do, but it's not leaking, so we are just not worried yet.

when the sunroof starts to rust, its fucked. it starts rusting the metal seems inside and its not worth it to fix.

+1

[egk2]

Yes, when you see rust forming on an e30 sunroof panel, it's a wrap.
The feet on the sunroof panels also tend to rust which causes the
typical sunroof sag. Buy a new panel.