Painting heat exchangers

[need RX7]

My FC's oil cooler is looking shabby these days, so I was thinking of cleaning it up and spraying it with some aluminum colored high-heat spray paint. Are there any potential issues with having paint covering any heat exchanging surfaces?

[chibikougan]

http://www.newton.dep.anl.gov/askasci/eng99/eng99320.htm

http://www.eastwood.com/eastwood-radiator-black-paint.html

[need RX7]

http://www.newton.dep.anl.gov/askasci/eng99/eng99320.htm



For normal temperatures the color of a heat radiator makes no difference so long as the color is not metallic, like silver.

Huh. I guess I won't do that then.

[Prodigy]

For normal temperatures the color of a heat radiator makes no difference so long as the color is not metallic, like silver.


Don't know what you read, but according to one reply...
Dont do your planned silver, just do black


J.

[need RX7]

Don't know what you read, but according to one reply...
Dont do your planned silver, just do black


J.

Yes, I suppose black would look better than old, dirty aluminum.

[Pete_89T2]

Why not just give it a thorough cleaning and call it a day? A good degreaser/engine cleaner and a pressure washer will do wonders on an AL oil cooler.

You'll have to get it really clean anyway before you paint it if you want the paint to last.

[need RX7]

Why not just give it a thorough cleaning and call it a day? A good degreaser/engine cleaner and a pressure washer will do wonders on an AL oil cooler.

You'll have to get it really clean anyway before you paint it if you want the paint to last.

I'm just concerned about it getting all dull again once exposed to the elements without any kind of coating. You are right though, I will have to clean it thoroughly to paint it, so I'll see what it looks like at that point and make a decision.

[RETed]

Almost any "paint" is going to introduce a layer of insulation.
This goes counter to what you want in an efficient heat exchanger.
The only exception is perhaps (aluminum) anodizing, which is basically a dye.

If you want maximum performance, don't paint it.
Bottom line.


-Ted

[C. Ludwig]

Almost any "paint" is going to introduce a layer of insulation.
This goes counter to what you want in an efficient heat exchanger.
The only exception is perhaps (aluminum) anodizing, which is basically a dye.

If you want maximum performance, don't paint it.
Bottom line.


-Ted


Truth.

[Slides]

Anodizing adds a layer of aluminium oxide (which carries the tint), which is more thermally insulative, although not that bad.

Even if you don't believe established emissivity theory and have no formal physics learning, an anecdote from someone who used controlled conditions may give you a clue.

I have a mate who before painting bits in his engine bay experimented with a rubbed back (to remove the red surface finish) bare aluminium coke can and one painted black, filled with water from the same kettle, black one cooled faster, as black body radiation theory would suggest, despite the fact it was covered in paint.

I would suggest leaving it bare or a light coat of black. There is a reason copper radiators and OEM steel sumps were always sealed with black paint.

[C. Ludwig]

I've been up close and personal with a lot of high end race cars and, to the best of my recollection, have never seen a painted radiator in one. The Audi R8 at Mid-Ohio back in 04 comes to mind. Audi has left no stone unturned in their LeMans program. If black was an advantage they would use it. And they don't. The R18 still doesn't use a black radiator. Maybe they haven't thought of doing the Coke can test?

[Monkman33]

I thought the black coating originated with copper radiators to keep them looking aesthetically pleasing.

[Prodigy]

I just painted my oil coolers on my R1 FD, thru had copious amounts of red over spray from a less then maco quality paint job, and the red bugged me horrendously...

Will it effect the ability of the exchangers to exchange temperature, I honestly believe it will, do I think that that little bit of paint that on it is going to make enough of a difference even if I had numerous datalogs of before after painting, that a change in temperature could be proven, I highly doubt it, and if it did. Are those few potential degrees difference really going to change how for Most of us, our street cars function?

Im confident enough to say no...

Sorry for spelling/grammatical errors, phones suck to type short story's on...

J.

[FC Zach]

If you do go the cleaning route be careful with pressure washing, the fins will be beat to hell. Purple power is awesome and works very well but don't let it sit on the aluminum long because it will etch the aluminum and leave it looking hazed. If you want to soak it in cleaner use something like simple green.

[need RX7]

Well, after all the input, I decided not to paint it. I did hit it with some degreaser in conjunction with a power washer, focusing mostly on the end tanks to avoid potentially damaging the fins. It looks better, but will need some detail work with degreaser and a brush.

[RETed]

Thought this was appropriate...

https://www.youtube.com/watch?v=f1QL9veQaNg

So the answer is YES and NO.


-Ted