I'm repainting my engine tin and resealing the engine...is it OK to paint the push rod tubes or do they need to left alone for cooling or ?

No, don't paint them and if they are rusty get new ones as they are fairly cheap.

You can paint them if you really want to... They contribute some cooling, but not a huge amount that I have been able to tell. A very thin coat of flat black may help them radiate heat slightly better--but a thick coat of paint (especially one that looks really nice!) will keep heat from transferring as well.

I'd leave them alone, myself. But then again, I'm lazy.

--DD

If you paint them with a thin coat of bright colored paint its easier to find leaks.

Pink is a nice, cool color. Of course, it will soon be covered with oily brown, which is pretty cool for model railroad stuff.

Why?

not that it makes a difference but..

flat black has an emissivity of .97-.99 which is one of the highest of all finishes, but it has a 1:1 ratio between emissivity and absorptance, so it will absorb heat at the same rate.

white (depending on brand of paint) can have up to .92 emissivity. Not really much of a difference comparatively with black, but it has a 3:1 ratio Em/Abs with only .22 or so absorptance.

In a hot environment white can sometimes be a better choice due to the fact that it sheds heat quickly but is not absorbing other radiation resulting in a cooler object.

What is important is the equillibrium temperature the object has, basically the balance between its absorption and emission. White will always have a lower equillibrium temperature than black.

Not that it makes a bit of difference though in this situation, like I said.


Dont polish your engine case though, as that will drop the emissivity from about .20 for oxidized aluminum down to about .03 or less depending on how much time you spend with the Mothers.