The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by Max Gearhead, Jun 29, 2012.
Is it OK to paint an aluminum radiator black and if so what kind of paint would work best? Thanks.
Yes, use radiator paint it is specifically thin for radiators. Eastwood has a good one.
Hey Jim, I painted mine on the Roadster two years ago with Duplicolor engine paint, low gloss black. It's held up well. I just painted the front that shows through the grille. I'll get around to the other side maybe this winter when I can take it out of the car.
Might want to look into the Eastwood Radiator paint that Probesport mentioned, I didn't know about that.
i used dp on mine worked good
Use a scotchbrite pad to scuff the tanks good and wipe them down with wax and grease remover so you get good tooth, and then lay on THIN coats. You don't want to keep the heat trapped inside the radiator and a heavy coat will act as a blanket somewhat. You want just enough coverage to make it black.
I used Rustoleum barbecue grill paint from the hardware store.
Bare aluminum radiators really look out of place on a hot rod.
Is Kal Guard still on the market? Thin header paint, draws heat from the surface of whatever it is applied to. I believe it is black. Also there are radiators that are black anodized from the manufacturer. If your radiator is natural now maybe the anodize (if cheap enough) would be the way to go.
use line-x or black bed liner, it will last forever! don't.
line-x ?? that would clog all the opens of the radiator wouldn't it. that stuff is thick..
Way back in the 70's I worked at a radiator shop. the radiator paint we used was some kind black stuff that got mixed with gasoline! Just an open bucket of the stuff with a siphon sprayer- kinda like an shutz gun. Guys with torches soldering less than 20' away. Ah, the good ol' days
I sprayed mine with duplicolor engine enamal flat black. Never had a problem overheating and it has held up well.
I fogged some satin black on the fins of mine, just so it wouldnt stick out like a sore thumb through my grill. It works fine, does not restrict flow, and I just used some cheapie rattle can paint from the hardware store.
Max Gearhead -
I have used anodized coating on road race radiators and street radiators and find that under extreme conditions, the anodized coating preforms better as far as allowing the radiator material to cool better. That said, if your engine is stock or has a mild hop-up, and the radiator is clean and in good order - heat proof paint ( above post mentioned BBQ paint ) will certainly work.
Best of luck,
I used Eastwoods black self-etching primer. Hope it would not flake off, worked very well.
So how come a car radiator has to be black to be effective when you can paint the one's in your house any color and they still work OK...
Must be a slow day at the office...
Im sure the color does not matter as much, black just blends in better in my opinion.
While I am not a fan of any aluminum radiators, radiator paint is made specifically for the purpose and is thinner than regular black paints allowing for better heat dissipation - which is the primary purpose of a radiator....
Hopefully your cooling system is not so marginal that a layer of black paint will keep it from working....
Flat black dissipates heat best of all colors as proved by the Italian Motorcycle Mfg for their racing bikes , and, what color did they paint the old coal and wood burning stoves way back when
Whatever one you choose to use you must use one with a matt finish.
Anodizing would be best!
Thanks much for the replies.
I'm going to stick my neck out here and say that the color of the paint has nothing to do with dissipation. If the radiator is in direct sunlight, sure. We all know that white reflects LIGHT (not heat) and black absorbs LIGHT. As a result, black gets hot.
If you have two identical items on your work bench out of direct sunlight, one black and one white, is here a temperature difference? No. Regardless of the temperature of the shop.
Okay, rant over. Please continue.
***EDIT*** I know most of you 'get this' but I keep seeing it over and over on the HAMB. If I can help one person by pissing off 5 I've done my job.
I would think a thin coating of heat resistant black would actually HELP to dissipate heat.I worked with someone many years ago who had just graduated from engineering school and one night we were discussing heating problems in modified cars.I was having cooling problems in my 50 Oldsmobile that had a 475 cu. in. stroker motor in it.He mentioned a study that was conducted by(I believe) the SAE in regard to heat dissipation of aluminum surfaces(specifically intake manifolds and valve covers) and it was found that black crinkle finish surfaces actually run cooler than bare aluminum surfaces.He was running a 66 Corvair with a 365 hp 327 in the back seat area and had made extensive use of the black crinkle paint available at the time with very much success.
I'm not an engineer but there is a principle behind the theory.While dark surfaces will most certainly absorb rather than reflect sunlight(and therefore heat)they also have the ability to dissipate heat much faster which is the whole purpose of a radiator anyway.
I saw the rad man paint my rad in my ol 55 f100 20 yrs ago....he too, used a very thin black with gasoline and the important part....he said DO NOT ever spray paint staight on to the rad...you do not want the interior part of the rad with any paint on it for efficiency purposes....instead....spray the rad at a 45 degree downward angle and it looks like its all painted black but really only the front portion gets any paint....my 2 cents worth....
I am running an alluminum rad in my vette from Dewitts Rad...in all this heat....about 180 is max....much better than the orig GM 427 rad in my 327-350hp with air vette.
A wrinkle finish WOULD dissipate heat better than a smooth finish, hence cooling fins on heat sinks. More surface area, better cooling.
I've been painting the shit out of aluminum radiators for years and have had no ill effects. in fact to get it black you have to shoot it from every angle or its gonna show.
Many thin coats from every angle, straight on, 45 from the right, left top and bottom. repeat till your happy. I can just about guarantee that it wont make any difference at all.
We must have worked at the same shop. Lol!
Heat is light in the red and infra red part of the spectrum. Black absorbs that light [heat]. White reflects it back into the radiator. I went through this back in the stock car racing days. Guys would paint their engines white because it would be easier to see any leaks, then they had heating issues. We painted ours black and they stayed cool. It wasn't long before everyone was painting them black. Some tried painting over the white paint and they still got hot. They finally sprayed stripper on, pressure washed the paint off, sprayed it black and cured their heating problems. We painted the headers white to keep the heat out of the engine compartment. Now they use ceramic coatings on the headers to keep the heat in.
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