|Inside of upper vent - not much rust.|
Rust is insidious. If it isn't removed, it will just continue to eat away at the metal, so it really needs to be removed wherever I see it.
I got most of the caulk out of the area around the vent and the sides, then started using my Dremel tool with sanding brushes and a Dremel multi-tool with sander pad and very rough sandpaper to sand the rust and paint from inside the van. I got most of it but there are spots that are rough and still iffy, especially on the inside of the vent hole. The Dremel goes thru the sanding brushes very quickly but does a pretty good job getting the rust off. There was more rust just under the paint a few places on the outside. I was hoping not to have to do paint removal beyond the edge where the vent covered the hole but there's a couple places that had to be cleaned off. Otherwise, the rust would just eat away under the new primer and paint. It took about 4 circuits of sanding and cleaning before I thought it was cleaned up enough.
|Inside of vent cleaned up and ready for bondo.|
One more round of cleaning up the surfaces, then I painted it all with Must For Rust making sure it got into all the crevices. It is a product that neutralizes rust in preparation for repainting. Since the temperature is cool, it will take longer for the product to work but it already looks a lot better. I sanded it once again, then retreated the metal with Must For Rust.
|Lower vent hole - had to remove quite a lot of the paint due to rust.|
|Upper vent removed - not much dried up caulk under it|
When I removed the upper vent, it was in a lot better shape than the lower one. There was only a little rust in one corner. I removed the skimpy caulk and the mold that was growing on it. Then burnished away the bit of rust on the lower corner, sanded the inside and edges to get the sharp edges off. Treated it with Must For Rust. That stuff really does halt the rust.
|Upper vent cleaned up and ready for primer|
I got a small Bondo kit to strengthen the inside van wall around the vent. I also got a 1" aluminium lath to install right next to the van hole that the screws will go thru for added support. I also got stainless screws for the vents to ensure they won't rust. Galvanized always seems to rust eventually. The Bondo must be applied to clean metal, so I took extra care to sand off all the paint and primer where it will go.
Cleaned it all up, then patched the particle board covered with plastic walls with wood filler. Tomorrow, I start applying the Bondo on the sides to support the weak metal. After that is applied and cured, sanded, then I can paint the primer. Getting close to the end of this mission creep problem.