Unless you live in the arid southwest, you know the horror you feel when you see the paint on an otherwise trusty Jeep starting to bubble. It means that rust lies beneath and is slowly but inevitably eating your Jeep out from under you.
Here is what it looked like...
Here is what it looked like when we started out. We weren't sure how far the cancer had spread at this point, all we knew was that we had a problem.
The best thing to do is to start digging as soon as you see the paint bubbling up. If you don't, you'll end up with what you see here. The beginning of the fix is the most painful.
Often the paint bubble is indicative of a much larger problem. So, here is a step-by-step on how to cure your body of cancer. Er, your Jeep's body.
The first step towards a cure...
The first step towards a cure is exploratory surgery. You've got to get in there, find out how far the rust has spread, and determine exactly where good metal is. In this case, we used our rust-divining rod (aka screwdriver).
Once you figure out the boundaries,...
Once you figure out the boundaries, you'll need to cut the cancer out. We like to use a thin metal cutting disc on the angle grinder. Notice that the rust had spread all the way up under the hinge, requiring removal of the hinge. Once the rusty metal is cut out, prep the area to be welded with a flapper wheel to remove the paint.
Cut a piece of cardboard to...
Cut a piece of cardboard to size and transfer the hole to whatever sheetmetal you will be using. It is much easier to trim cardboard and will result in a tighter-fitting patch panel.
There are two basic ways to...
There are two basic ways to create a patch panel: overlapping or flush fit. Overlapping is easier to weld-in, but you need to crimp a step into the sheetmetal with a special tool so that the patch sits flat when you are done. We didn't have the space for the steps here anyway, so we just cut it to fit flush. A magnet will help you hold the panel in place while you tack it. Make sure it is flush and level with the surrounding sheetmetal and use small tack welds. Double-check that the panel is still flush after each tack weld. The tighter the patch panel fits, the better the final fix will look.
It is good practice to stitch...
It is good practice to stitch weld the panel in. Weld a small bead, and then alternate to the opposite side. To keep the metal from warping a good rule of thumb is that if you can't put your hand on the surrounding metal, it's too hot. The same goes for grinding the weld down; make sure the surrounding area stays cool. Don't use water to cool it down, as that can make the metal warp too. Grinding the weld with a fine flapper wheel will result in a good-looking finish.
We hate Bondo, so after painting...
We hate Bondo, so after painting the patch we covered it with some Gen-Right 1/8-inch-thick shorty corners. We made the panel under the tailgate to cover some other damage, but Gen-Right now offers that panel as well. You need to cover front and rear of the patch with paint. If the back isn't accessible, drill a small (1/8-inch or less) hole for access and use a WD-40 straw to get the paint in there. After the paint dries, use silicone to seal the drill hole.