Painting Cylinders?

Bill Richardson · Post by **Bill Richardson** » Fri Jul 20, 2001 8:53 am

I have seen people mention painting your cylinders to stop them rusting.

Is this a good idea? If so, what type/brand of paint should I use?

Thanks.

C.R.Acker · Post by **C.R.Acker** » Fri Jul 20, 2001 12:28 pm

If you do paint them, paint them black. This will help cooling. Im not sure if it is even safe to paint them.

Mike Scott · Post by **Mike Scott** » Fri Jul 20, 2001 8:56 pm

While I don't think the paint will do any damage I don't beleave it will make any differance. The paint probably will not stay on, unless you powdercoat them.

JohnConnolly · Post by **JohnConnolly** » Fri Jul 20, 2001 10:45 pm

it runs cooler, and the paint stays there. I've done it for over a decade

type11969 · Post by **type11969** » Sat Jul 21, 2001 7:27 am

John-
What type of paint do you use? How hot do cylinders get?

-Chris

CPRcubed · Post by **CPRcubed** » Mon Jul 30, 2001 4:03 am

Heat transfer occurs in three ways: Conduction, Convection, and Radiation. Air-cooled motors will use Conduction and mainly Convection (air flowing past the cylinders to remove heat) for cooling. Adding any type of additional coating will slow down the convective effect. It will act as "insulation". I would leave them plain (but that is only my opinion

). Cheers!

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1970 Bug (stock & rusted for now), 1994 F350 CC DRW PSD, 1971 Airstream. Life is good in Bear Valley Springs!

AircooledNut · Post by **AircooledNut** » Mon Aug 13, 2001 7:24 am

Hmmm.... How does it saty cooler? I know from racing American cars that if you paint Aluminum it will hold the heat in. That is why Aluminum heads, Intakes are clean and unpainted. So it would seem that if you painted steel cylinders it will have the same effect. Teach me o great one.....I need to know!

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Steve Waters
00 Turbo Beetle
66 beetle 2332cc

63ragtop · Post by **63ragtop** » Mon Aug 13, 2001 12:30 pm

They were made unpainted for a reason, if you paint them, they will run hotter.

Derrick from NC · Post by **Derrick from NC** » Mon Aug 13, 2001 6:43 pm

I've seen Harly Davison bikes with black cylinders & heads from the factory. I assume they are powder coated. Also some of the companies that have the hi-tech coatings for combustion chambers, valve springs etc., also advertise a black heat emitting coating for aircooled(motorcycle) heads and cylinders that has been tested(??) to run cooler than an unpainted counterpart.

aussiebug · Post by **aussiebug** » Mon Aug 13, 2001 9:19 pm

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by AircooledNut:
Hmmm.... How does it saty cooler? I know from racing American cars that if you paint Aluminum it will hold the heat in. That is why Aluminum heads, Intakes are clean and unpainted. So it would seem that if you painted steel cylinders it will have the same effect. Teach me o great one.....I need to know!<HR></BLOCKQUOTE>

Painting any hot surface with a thin coat of black paint will help it radiate heat faster. Similarly, black paint on a cold surface will help it absorb radiant heat faster.

So a thin coat of flat black hi-temp (engine) paint on the cylinders will help them shed heat. Same with the pushrods underneath, although here the best results would probably be to paint the outer ends (under the heads) white (as the heads run hotter and you don't want that section of pushrod tube to absorb more heat), and the sections under the cylinders black, as the oil flowing down those tubes is cooler than the air off the heads but hotter than the air off the cylinders.

This follows for other metal parts too - anything which contacts the oil (like the rocker covers) is best left black, but other parts - like the fan shroud - can be any colour you like, since they don't contribute to the actual cooling - just guide the air and so on.

In case you are wondering about this, VW used to supply an "actic kit" many years ago for very cold climates; to help keep heat in the engine. One of the major items in that kits was chrome rocker covers, as these reduced the heat loss from the oil in the head area.

Regards,

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Rob
Rob and Dave's aircooled VW pages
Repair and Maintenance for the home mechanic
http://www.geocities.com/aussiebug1970/index.html

vwnate1 · Post by **vwnate1** » Thu Aug 16, 2001 12:17 pm

Flat black barbeque paint should help but V.W. doesn't think it helps , neither do I .
Run synthetice oil after breakin , that will definately lower your operating temperature .

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-Nate
Filth & Greed Imports
(the LAST honest VWshop)

clarkblumberg · Post by **clarkblumberg** » Tue Oct 23, 2001 9:24 pm

Air cooled aircraft cylinders have been painted for years and years. These are also horizontally oposed engines where cooling is critical. Regards, Clark.

JohnConnolly · Post by **JohnConnolly** » Tue Oct 23, 2001 9:41 pm

it is true a bare iron cylinder will cool better than one painted black, but this is only the case until the iron RUSTS, then the black one is better at heat transfer. How long do you think the bare iron cylinders will remain rust free? That's the $64,000 question.

Derrick from NC · Post by **Derrick from NC** » Wed Oct 24, 2001 4:15 pm

Any particular brand paint you recommend or should they be powder coated?

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Wed Oct 24, 2001 5:44 pm

Hmmn.
Seems to me that a slightly rusted cylinder will creat MORE surface area to be effectively cooled, like beadblasing a cylinder head. The more thee air has to linger around the object, the more cooling it will accomplish, in my way of thinking..

Stop and think, if VW spent millions on the doghouse fanshroud update, they had a reason for not painting cylinders, maybe they wanted them to rust, slightly.

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Jake Raby
Raby's Aircooled Technology
www.aircooledtechnology.com