Painting a radiator?

Just wanted to hear some thoughts on painting a radiator when you do a restoration. I have seen some painted the same color as the tractor and some painted black. Don't think I have ever seen one left bare copper. What do yall think about the color?

I don't know your model but most are radiator black. It's a special radiator paint. The regular tractor paint is to thick and can clog it up. And alter
cooling ability so I've been told.

The paint on the radiators of years gone by was black and it was to aid in dissipating the heat.

Paint with black radiator paint to avoid loss of heat dissipation.

Dean

The whole "black body radiation" thing as it might apply to radiators in old tractors is pretty much an old debunked myth, IMHO.

Typically, way back when, they were not masked off and are the same basic color as the tractor, not "radiator black". YAMMV!

We paint them flat black for color contrast not for heat dissipation.

While a black object might absorb heat when sitting in direct sunlight, objects painted black dissipate heat quicker than other colors. I remember taking a college chemistry class many years ago where our experiments showed how fast ice water would melt from a black container.

Bingo.

That's one of the reasons why OEM radiators are painted with black radiator paint.

This is not to say that some agricultural manufacturers may have avoided masking them when the tractor was painted in order to save costs.

Dean

I paint the core matt black, then mask off the core and paint the rest of the radiator the same as the tractor, I just think it looks better that way.

I agree with the "thick paint" comment. I think [no evidence to speak of] that the coating must be some sort of thin black coating, done to aid heat transfer, but it is not black paint. I agree, too thick. If anything, I'd go to hardware store and investigate black stove polish / coating. I think that must be the proper thinness.

You are right, Google black body radiation.

I leave my cores bare copper. Paint may block the heat transfer and with grilles and/or shutters you can't see them anyhow.

Only use a Thermal paint Made for painting them or they can stop transferring heat, a friend who ran a radiator repair shop for 40 plus years straightened me out on that point, he always used a air suction gun to apply it so it was a fine even coat,, but its yours do what you like

I have an old Ford sales brochure from the late fifties after the XX1s came out. It uses actual color photographs instead of the "colorized" black and whites of a few years earlier. It shows the red shroud, with the black core just behind it. In order to decide what color to paint things, if you want it to be original, you need to think of the assembly line process. Most tractors were assembled except for wheels and tires, seat, radiator and hoses, sheet metal with gauges, wiring, carburetor and throttle/governor linkages. After painting the assembled chassis all of the above were added. I think that it was highly unlikely that a single inch of masking tape was used. As said earlier some contrast is pleasing to the eye, so the owner can certainly add any different painting in order to please his eye. My pet peeve is black starters and generators, because we know that a a new tractor with a black starter would not start.

Use the proper Radiator Black paint.
It's formulated for radiators to be thinner and helps transfer
Heat.

Tom

When we were racing stock cars, radiator shops always painted the radiators black with a special paint to aid in heat dissipation. Reason enough for me.

My thoughts are to paint them black and the difference between regular black and the so called radiator black are
most likely un noticeable just use light coat

I think painting is just for looks. I think it does more to reduce heat transfer than help it.

There are three types of heat transfer methods.
1. Conduction: The transfer of heat through a material. Materials like aluminum, copper and brass are good at conducting heat through them. Plastics are poor at conducting heat through them. Paint is more like plastic and isn't a great conductor of heat. The thicker the material including layering paint on metal the worse it is at conducting heat. For conduction the paint is hurting heat transfer. Conduction has to happen to get the heat out of the radiator to the surface of the radiator core.
2. Convection: The transfer of heat from the fluid or gas from a solid surface. This happens twice in a radiator. On the inside when the antifreeze transfers the heat to the radiator core. On the outside when the radiator core transfers heat to the air. Convection is greatly improved by fluid or air flow. Thus the need for a fan.
3. Radiation: From a surface out to something to absorb the heat. Since the surface of the radiator is mostly internal. Meaning all of the fins face each other radiation doesn't help much. There is not a lot of surface area on a radiator that actually can radiate heat out and have it absorbed by something. Radiation from one fin to the next one doesn't help because each fin just absorbs the same heat it is giving up. Radiation from the radiator to the engine doesn't help because the engine is also radiating heat to the radiator. So the only surface in the radiator that can actually radiate heat is the front through the grill. The grill actually blocks the radiation and absorbs heat which warms it up warms the air flowing to the radiator. For radiation to be effective the radiator needs to be sitting out in the open with all surfaces exposed not enclosed in sheet metal sitting in front of a hot engine.

In a radiator there is first convection from the antifreeze to the radiator core. Then conduction from the radiator core to the fins. Then convection from the radiator surface to the air. The most resistant part of these three is the convection of the radiator surface to the air. Any radiation that happens is just a small part of the overall heat transfer.

I just watched an interesting video from Mythbusters on the effect of painting an air-to-air intercooler black vs. the original bare aluminum.

They ran two tests each way, one with air flow and one without.

WITHOUT airflow the black unit was more effective at radiating heat.

Once airflow was added, the difference dropped to 3?, which the Mythbusters called "insignificant".

ASSUMING a tractor radiator (which typically always has airflow to it in operation) behaves the same way, there MAY be a SLIGHT gain by painting it black.
Black it

Years ago, (many), I painted a 57 Buick I had. The parts guy told me that the cheapest paint color he had was black. I bet that figured into mass production reasons they were black. gm

I wasn't really thinking of the performance of cooling when I started this thread. I was more thinking of looks to break up the green a little. After reading this I will probably paint it black. Thank you for the replies

Now deceased HP perfectionist and all around automotive performance guru, Bill Jenkins (Grumpy's Toy) dealt with this a lot when trying to tweak every once of HP out of every engine. He went so far as to paint the lite weight polished aluminum or chromed steel valve covers from the likes of Holley, Edelbrock, Moroso and the rest of them black because it dissipated heat faster than the polished or chromed jobs. In his ideal world, leave the stock factory painted valve covers on, get them far enough up from the head to be able to fix a girdle to the rocker arm studs to keep them as still as possible, and if need be because you're not good at welding, drill holes through them over each rocker arm and put a screw through them for the oil to fix to and drip down into the rocker arms as lubrication.

So when it comes to performance, is painted better than non-painted? Arguments can be made on both sides, to include protecting the metal from rust or oxidization.

Mark

Hello, currently I am thinking of painting my radiator, and while searching on Google, I found a paint that seems to be good. However, since I have never used a product like this before, I would like to have your opinion to avoid making any mistakes. Thank you :roll: :lol: [/url]

(quoted from post at 23:42:59 05/30/23) Hello, currently I am thinking of painting my radiator, and while searching on Google, I found a paint that seems to be good. However, since I have never used a product like this before, I would like to have your opinion to avoid making any mistakes. Thank you :roll: :lol: [/url]

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It is for interior use. Your primary concern should be the protection of the soft metals, copper, brass, aluminum, solder, from the weather. While some paints are formulated to help reduce heat radiation, and some help a body to absorb heat, I don't believe that there really is any paint that will help heat to be radiated.

When I asked about what paint he used a radiator repair shop paints them with a paint that will dissolve in there cleaning vat. He was never happy to see them painted with anything else.

If the lead did not kill'em the paint did.