Ospho/rust bonding agents

[Bob L]

I just took a pressure washer to my engine compartment, and it's looking awesome. The motor was pretty rusty, and the corrosion had lifted off the paint. The engine looked looked like someone had sprinkled wet sawdust all over it.

Well, that's gone now. But now the block is bare, and still has a coating of rust that is "growed-on". The West Marine people recommended Ospho or some other sort of metal prep that "turns rust into metal". Right. Well, if it melts the rust and makes it ready for painting, then that would be a good thing, for now at least. I know I should pull the engine and rebuild it, but I just don't want to do that this year.

Anybody out there with experience with Ospho, Rust-Lock Metal Prep, other products, or a better idea?

Thanks,

Bob

[dasein668]

I believe these converters work by bonding with the iron oxide to form a more stable compound. I've never used them, but what I've heard from a friend with a steel boat (ugh!) is that they work best on light areas of rust?if there is really heavy rust then the converter converts the surface rust, but leaves rust underneath which leads to bad news down the road. I'd say that you would probably do well to wire brush (and maybe use naval jelly or similar) on the areas first to get as much rust off as you can, then use the converter to help convert any minor remaining rust.

But again, I've never used the stuff myself so take it for what its worth!

[Tim]

That rust converter stuff, whatever it's called, is very good at turning surface rust into a stable base. Heavy corrosion should be removed/cleaned first, but when the stuff is applied it turns the rusted areas into a black, stable compound. It does work, but again: it's just for those areas of typical surface rust, not for heavy corrosion. Obviously it doesn't replace the structural elements of rusted metal. As a primer, though, and rust stabilizer, it is very good stuff.