It is wintertime southeast Pennsylvania, so that means lots of road salt. Third generation 4Runners on the east coast are notorious for frame rot and I spent a lot of time this fall repairing the damage that was done over the past 21 years and hoping this will help it survive many more PA winters.
This meant spending a lot of time scraping, grinding, and sanding the rear 1/3 of the frame. Once it was cleaned up enough to my satisfaction, I followed the POR-15 process (degreaser, etching/prep, and then coating) and top coated with some flat black paint.
While poking and prodding at the frame I wondered what I could do to actually kill or treat the rust that was occurring inside the frame rails. Obviously, there was no way I could get into the inside of the frame rails to scrape away the surface rust like I could on the exterior of the frame. I spent some time searching around the Internet and found some products specifically designed to be used just for that purpose. These rust treaters/inhibitors are spray cans with 18″ or so attachments that allow for you to get into the inside of the frame rails through the cutouts in the frame.
Sounds like another weekend project once the weather warms up a bit.