I have a fairly new radiator, but there is some chips in the paint on the sides and some of the fins have discolored .Do I need a Radiator paint or will any high heat paint work as long as I dont apply it to thick.

 

I am pretty sure any high heat paint will work.

 

I know they make radiator spray paint..I just dont know what the difference would be.As long as its HIGH Temp.

 

Probably don't even need hi-temp paint, it can't get much over 200 degrees if there is water in it. Most regular paints will do that with no problems....Tedd

 

Not that it gives you the greatest look, but when I had the radiator in my '73, which was black when I bought it new, repaired, the shop had to strip the paint to solder or whatever the leaks, and they left it unpainted. They told me that, for best cooling, to leave it that way. I don't worry greatly about the car's "show car" appearance, so I did leave it that way. Shiny metal under there, but it cools just fine.

 

Any time I have had any radiator repair done, they have always painted it black when they were done.

 

Thanks guys. Just going to give it a lite coat of flat black

 

Radiator paint is thinner, so it doesn't hold the heat as much as regular paint. I don't know how important that is on the tank, but it is very important on the fins.

 

I don't get this. Why would you want the radiator fins to "hold the heat"? The whole point is to eject heat. By this argument, as my radiator guy said, the best course of action is to not paint it at all.

I know people have painted radiators forever, and the argument is that the black color increases thermal radiation from the radiator and increases heat rejection, which is what you want.

However, I've always had issues with this. The primary mode of heat transfer for a radiator is convection (heat transfer due to motion of a fluid carrying that heat, whether it be air, water, anti-freeze, or whatever) from the radiator fluid to the metal of the radiator fins, then conduction (heat transfer by the movement of electrons, or why your aluminum frame window feels cold to the touch but your wood window frame does not) through the radiator metal, and finally convection again from the external fin surface to the exterior air, which is presumably moving at relatively high velocity through the fins due to either the fan or the forward motion of the car.

Only a small amount of thermal energy is transfered to the surroundings by thermal radiation, which is the reason for painting the radiator black.

Any coating on the radiator surface adds resistance to the conductive process of transferring heat from the metal radiator fins to the outside air. If the coating is thin enough, its effect will be negligible, and this is what you want if you paint the radiator. You're painting it to make it pretty, not to make it a better radiator.

The emissivity of the surface affects how well the surface loses heat by radiation to the surroundings. Painting a radiator black does not necessarily increase the emissivity of the surface, and, depending on the paint, can actually decrease it. Thus, at best, painting a radiator doesn't harm its heat-ejection efficiency, and, at worst, it decreases its efficiency slightly.

 

Did you misread my post? Who said you want the fins to hold heat? I said the radiator paint is thinner so it doesn't hold the heat. And not holding heart is especially important on the fins (because that is where the heat transfer takes place). Radiators were painted when new and I assume they used radiator paint. The radiator paint I have claims on the can that it is thinner than regular paint, and to spray it sparingly, just a mist coat on the fins.

 

I didn't misread your post. I read your post.

This is what it said:
The way I read this you're saying that radiator paint doesn't hold the heat as much as regular paint. Then you say that this is very important for the fins. The implication is that holding the heat is important for the fins. If you what you meant is the opposite, it certainly doesn't come across that way.

 

Radiator paint is thinner, so it (the thinner paint) doesn't hold the heat. I don't know how important that (the thinner paint) is on the tank, but it ( the thinner paint) is very important on the fins.