Pressure washer to clean the areas of loose rusr and dirt, then spray the areas with Ospho. After 24 hours, hit it again with the pressure washer to remove the white crusty residue which is a byproduct of the conversion of iron oxide (rust) to iron phosphate (inert coating which is now rust free). Let ti dry and paint it if you can get it in there. If you can't, don't obsess about it.
You are trying to slow the rust process down, not eliminate it for 40 years.
Last edited by 52Carl; 06/17/2021 5:01 AM.
