Some overhaul shops claim beneficial cooling effects of black paint on their engine. A hot engine in a cold surrounding, radiates energy from the hot object to the cold. This derives from Kirchoff's Law where good absorbers are also good emitters. Painting an engine black increases the amount of radiant energy emitted by the hot engine to its colder surroundings and it will be cooler than a non-black engine. There are fallacies to the above argument.
Most heat energy emitted by the engine is in the invisible infrared portion of the spectrum.
What appears to us as black, white, red, or green in the visible spectrum is not what we would see in the infrared spectrum. Painting an engine increases radiant cooling but the color of the paint doesn't. The second fallacy is that you also have to ask what happens to the radiant energy being emitted by the engine. Black paint has high absorbency and high emittance. Better would be white paint that has low absorbency and high emittance.