My good friend Rudy Legett told me about OSPHO for treating rusty metal prior to painting. There were several sections of rusted steel in my engine compartment that needed some attention. I wire brushed and/or scraped them as best I could and then used my PowerTank (portable CO2 tank) to blow off all the loose debris.
Next I brushed on a liberal application of full-strength OSPHO. The brush can be rinsed with water and re-used. Tomorrow I will brush on some Rustoleum low glass black oil-based paint. Should I look for something that can take high heat -- although I am not putting any paint on the engine itself?
In the photo, the shiny parts have been treated with OSPHO
George,
I recently cleaned and put OSPHO on all my structural metal in the rear of the engine compartment. I included the engine parts facing the rear of the coach which includes the flaked off paint I can see on your engine, the mounts for the alternator and A/C compressor too. This killed all the surface rust and primed the area for paint.
I then painted flat black everywhere and ended up with a clean looking back side. You have to look hard to see where the paint was flaked off of my engine.