I recently bought a 2000 Ford Ranger with a V6. The motor is nice and clean but the exhaust manifold is all rusty. My question is - how come they don’t paint these at the factory with heat resistant manifold paint or is this another downsize maneuver.
I’d expect it might have something to do with heat dispersion, but I’m no expert here.
thanks for clarifying this.
tcd 
I know some old Jaguars had painted exhaust manifolds. I don’t know if they still do, nor if any other makes did that from the factory.
Why doesn’t everybody do it? Because there’s no need. It’s cosmetic. What you saw is surface rust. You (and probably your kids and maybe their kids) will be long dead before that manifold rusts enough to get hole in it.
Supposedly there’s some heat resistant paint, that when used on exhaust manifolds improves a car’s performance because it keeps the exhaust hotter and allows it to escape faster. Dunno if it’s true or not.
A Ford Ranger is a nice truck but it is not a luxury vehicle. It’s built for durability but not to flatter. Therefore, a couple of factors come into consideration in the production process.
1.) Painting is the most environmentally unfriendly stage of auto assembly. The manufacturers use a wet process instead of powdercoating. Therefore is there is no compelling reason to paint something, why do it?
2.) My experience with heat resistant paints is that they emit a very distinct odor until they are fully cured. Jaguar can afford to paint a manifold and let it cure at high tempuratures before assembly. There’s no reason to do this for a Ford Ranger. If they didn’t cure paint your engine would stink like hell for the first 500 miles or so.
You think that’s bad. Check under your truck. Even new vehicles come with sporty rusted out sway bars.
You could take the manifold out and have in jet hot coated. Looks nice and lowers underhood temps.
Rust has a way of protecting the affected area… from rust. I call it “a protective layer of rust”. This goes for many things on a car. But it’s only my personal observation, not sure if it’s techinically, chemically true.
heat resistant paint is only that… resistant.
it will eventually flake or crack… the only thing that is semi permanent is jet hot and ceramic coatings…
or you could just use stainless steel, but as sparty said… its just a ford ranger.
I remember reading that bare clean aluminum almost instantly develops a thin coating of aluminum oxide which then retards any further oxidation. I don’t know if the same thing can happen with iron or steel.