[Terran]

So i did my weekly was today to get all the salt off, and i noticed that I'm getting some pinhole rust bubbles on driver-side rear wheel-well. I assume the best course of action is sandpaper, rust converter, touch-up paint, then a clear coat sealant?

The question following that is, where can i get some touchup paint in the dark green color? Dupli-color only offers a metallic wintergreen.

 

[Corson27]

I used this one and it matched the color on my 2001 Malibu perfectly.

http://www.fix-up.com/index_en.asp

Lasted a long time too

 

[Terran]

Am I better off with sandpaper and rust neutralizer or a dremel and neutralizer? They're all less then 1/8th diameter.

 

[ddavidv]

Here's the problem...the panel is rusting from the back side. There's a much larger area than what you are seeing on the outside. The only real way to eradicate the problem is cut out the effected area and weld in a new piece, but that's not something the home repair guy is usually capable of. The best you can hope for is to grind out the pinholes as large as possible with the Dremel, sand the area, treat with an appropriate product and go from there into finishing the repair. If you just use body filler forced into the holes I guarantee it will bubble up again within a year. You need a non-porous product to have any hope of buying time.

Foresters are one of the few Subaru models I see rust and that's usually the spot where they first go on the outer body. There must be a pocket that does not get paint or coating at the factory there. Condensation over time will cause it to rust.

 

[Tau137]

^^^ Yeap, "pinhole" usually ends up being a dime-sized patch. Without significant experience/skill, DIY touch-up repair will look butt-ugly. I'd suggest clearing a very small patch (only the area affected by bubbles), use some rust converter, and then touch-up. Might or might not stop the rust completely, but it will slow it down, and you will not have to invest a lot of time and effort to try to make it look good (and you will have a much smaller chance of thinking "I should have just let it rust").

 

[Terran]

ACK! Don't tell me this! Is there a way to get to the backside of that panel with neutralizer? Maybe when i do the rear brake swap?

 

[Tau137]

ACK! Don't tell me this! Is there a way to get to the backside of that panel with neutralizer?

No, and no point doing it either. If it does indeed rust from the back side, only "cut-and-paste" will work. But it is not rusting from the back - it rusts on the same side, from small cracks in the paint, sometimes advancing below the primer quite a distance from the point of origin.

Really, if you don't have tools/experience, and not willing to invest in shop repair - just leave it be, save money for the next car. Or try quick fix, but I'd not suggest that if the problem is extensive (i.e., more than ~5-10mm size patches of paint need to to be sanded off) and/or near panel edge(s).

 

[Terran]

Well I can't abide by rust at all. Personally I'd rather have a patch area of a slightly different color then rust. . I don't think its rusting from behind, I think it's rusting from gravel damage on the paint. Any guesstimates on what professional repair would cost?

 

[2.5x_sleeper]

I'm with you. I won't tolerate any rust on my vehicles & I'm lucky enough to live in a State that doesn't use winter road salts. Our vehicles will stay nearly rust free, with just a bit of TLC. Even our '95 Neon Sport is rust free. :wink:

When you see rust damage under the paint, the damage has been going on for a long time on the other side of the sheet metal. To control it, you need to get to the back area & apply a rust stop, which can be found via a goolgle search. Until this is done, I wouldn't bother with what you can see on the paint surface. :frown:

Bobby...

My MODding Journal

 

[Terran]

This particular panel is coated with seemingly intact undercoat which is what confuses me. Also, sorry about the huge photos, android phones have their limits.

 

[2.5x_sleeper]

Okay, then it should be easy to get behind the pin hole to see what's up. It's possible that there was a void, an area that didn't get coated properly with undercoat. I'd get under there & carfully remove the undercoat to look for the rust source. Use care not to poke too hard, since the rusted sheet metal could be very thin! You can get a can of spray on 3m Rubberized Undercoating, part #08883, to reseal the area you work on. :smile:

Bobby...

My MODding Journal

 

[Terran]

Funny thing is, doesn't seem like it's loose back there. I pressed a bit with my fingers and there was no give in the metal.

 

[2.5x_sleeper]

Have you tried to push a pin thru the rust spot to see if it goes thru? If not, perhaps moisture somehow got under the paint where it was chipped & started to rust. If that's that's the case, the repair would be to scrape the area clean of paint & rust. Then prime & repaint. :smile:

Bobby...

My MODding Journal

 

[Terran]

Well several of those spots are where gravel or the such has chipped the paint
I will try the pin method

 

[ddavidv]

You might get lucky, though it's hard to tell from the photos. If it all truly did start from the outside, you have a chance. But, if the paint is bubbling and there is no perforation that started the rust, it's rusting from the inside of the panel.