Need help repairing Exterior Rust problem

[firetridagger]

I need help on fixing exterior Rust but i have no idea where to start,

Thx

[robiewp]

Start with describing the problem.

[firetridagger]

well the rust comes from the inside of the body and it pops off the exterior paint.

[abew330]

a pic would be great!

[firetridagger]

i'll be posting pictures tmr.

Thx

[robiewp]

What you describe is very bad. It will either require replacement of the affected panel or for it to be cut out and replaced with new metal (welded in).

Rust is like cancer. if it's to the point where it's rusting through from one side of the body panel the only way to really stop it is to cut it completely out.

If you want to just slow it down, you could attempt to sand it down and paint it with a rust converter or encapsulating paint.

[donbryce]

I agree with robiewp, if you're talking about 'rust bubbles' in the paint, it could be 'major surgery'....or maybe not. Here's how the process goes, at least for me, and I've been patching up beaters for over 30 years:
- Minor surface rust can be repaired by using a stiff knotted-wire brush in your body grinder to remove all rust and paint, especially in the pin-hole sized 'pockets' where the rust has eaten away metal. Sandblasting with a small device that looks like a paint gun, with rubber nose pieces that concentrate the sand in a quarter-sized circle, is great for cleaning out those pockets too. Chemicals like POR are no good for visible body panel repair, but great for floors and inside fenderwells etc. You'll need filler to blend the surface and replace metal eaten away by rust, like what is in those 'pockets', and filler doesn't stick to chemical rust converters.
- Rust that has eaten right through will require cutting out and replacing with patch panels. I usually make my own, easy for minor flat and curved spots, harder where there are compound curves. From your post, you probably won't be doing this yourself. I sometimes cruise the junkyard for pieces I need, cut them out and trim-to-fit , then MIG weld the panel in place. Body shop supply places sometimes sell made-to-fit patch panels too.
- I'll skip how to grind and prep the welded in patch panels, and move on to preparing a clean surface for paint. Use good quality body filler, apply, and sand until the contour is right. Apply finishing filler, then prime, lots of sanding and priming, and when the surface is smooth and blended into the surrounding paint, spray base colour and then clear-coat.
- By now, you get the idea of the skill and materials required to do a second class job. A first class job will require repainting the entire area around the repair, if you want the end result invisible. Like on a rusty rear fender dog-leg, the whole fender will need painting up to boundaries like molding and lights, so there is no 'tape line' or change-over from repaired paint to old. Color matters, some are harder to blend, especially metallics.