While the exterior of my truck has clearly been repainted at some point and looks very nice, the engine bay is a bit of a mess. As I do the mechanical overhaul, I also would like to make sheet metal repairs and remove the rust from the engine bay. To that end, I spent this morning cleaning up, sanding down, and removing surface rust from the inside of the left front fender. There is no serious rust, other than the just behind the battery tray where it clearly rusted through at one point. That area appears to be very stable now.
Before I started cleaning, I did my best to pull the wires from the engine bay wiring harness up and away from the fenders to keep them from getting wet.
Then I used a spray bottle to spray some Simple Green onto the fender, and a green Scotch Brite pad to scrub the fender.
After some time and elbow grease, the fender started to look a lot better.
After the metal was clean, it became clear that there was some surface rust pitting the fender, particularly in the area of the battery tray. I used a 150-grit sanding pad to remove the paint and surface rust in those areas.
Then I applied some Metal Prep to another Scotch Brite pad and scrubbed it into the bare metal where I had sanded away the red paint. The Metal Prep chemically neutralizes any remaining rust and also leaves a thin, rust-inhibiting coating on the metal which helps to prevent future rust. I wiped away the excess solution using shop towels so it wouldn’t run down the panel or dry too thick.
Here are a couple of pictures of the left fender after I finished cleaning it up and treating the rust. The bare metal that has been treated takes on a whitish-grey tone because the protective film is almost chalky.