My paint is starting to bubble a little bit on the rear fender. Can I just sand it down to bare metal, bondo over it and repaint it? Im afraid that it will come back worst so what does everyone recommend I do?

 

It depends. Rust of a funny thing. Paint bubbles because moisture is getting under it and pushing it outward. If you sand it down, bondo, and respray...it could very well come back. The only 100% true way to remove rust or moisture under the paint, is to cut the section completely out and replace it with fresh metal or a whole new quarter panel.

You can try and do what you asked, but if its really bad...it will just come back. Probably not worst but it will start to bubble again. If you're doing it yourself...I would try and sand it all down, bondo, and respray and hope for the best. You may get lucky and never see it again if you're able to sand it all out and its not that bad. If it comes back, then you may want to think about having some one form sheet metal into the same shape as the area, cut out all the rust, and weld in the new metal. Then sand, bondo, and paint. Apply something on back of the area too so that it doesnt rust from behind the panel.

Good luck!

 

^ that's ridonculous advice. If it's just a small spot, sand it down to bright metal, then immediately clean, prime, and paint it. It could be a local paint defect you can cure with a fresh finish. If it's a large area, you could still have the same problem with the same solution, or you could be in a "cheaper to replace the whole car" type situation. It depends.

How about a picture or three?

 

Same thing happened with my rear fenders. I did everything that visionz suggested other than cutting out the metal and welding new metal in, and it still kept coming back. Finally I ordered this stuff

http://www.por15.com/

That was over a year ago, and it stopped rust dead in its tracks. No more bubbling, fiberglass, sanding, or painting. The stuff is a miracle cure to any and all rust on cars.