To Paint or Not to Paint
 

To paint or not to paint?

What are the pro's and con's regarding the painting of aluminum and magnesium cases and other components during a rebuild of the early 2.0 - 2.7 engines?

I need some feedback from the experts about this issue.

Air-cooled aircraft engines of similar design and horsepower come painted from the factory and are completely painted at rebuild as a way to prevent corrosion. Hardware is often cad plated to prevent rust of steel parts.

The consensus on this board is it is never a good idea to paint your cases, regardless of material. Just holds in the heat.

Exactly. Heat, then weight is the issue. The cad plating, however is a great idea! I would think that for aircraft, heat is less of an issue (cooler at altitude plus that prop is a little bigger than our 11 blade fan. I guess they paint to prevent corrosion?

Just clean the sucker until you can eat off it

Thanks for all the feedback. I checked older posts concerning the issue and everybody seems of a like mind.

It's just hard to get a magnesium case to shine like new once it's oxidized.

Oh come on....a coat of paint does not weigh THAT much. After hours of cleaning up these mag cases, it's just so dissatisfying to see how poorly the cases still look. So...I've painted a case with no ill effects (read no overheating) just to check it out. And it looked great and it never peeled. The paint was from Eastwood.

Here's an unpainted case.
http://forums.pelicanparts.com/uploa...1079072383.jpg


Here's a picture of the painted case. I think it looks nice.
http://forums.pelicanparts.com/uploa...1079072411.jpg

Felmir

Thanks for the picture. It's truly worth a thousand words. The case looks great, what color paint from Eastwood?

The trouble is, you're never going to see it, and the effects are really unknown...

-Wayne

The paint is Eastwood "Detail Gray".

There is a benefit if you consider preventing corrosion an issue.

Anyone living close to the ocean with their car parked outside is going to be at risk unless their engine is covered with oil or paint. The salt spary is airborne and travels inland a significant distance when the wind blows onshore.

Any uprotected metal is subject to corrosion or rust (oxidization) unless protected. That's why aircraft engine manufacturers paint their magnesium and aluminum engines, nobody ever sees them either.

What about a coating as opposed to paint? I'm pretty sure there are thermal radiant coatings out there. I've seen thermal barriers used on exhaust and I've personally used oil release coatings inside engine blocks to aid drain back to the sump. There are even anti friction coatings for pistons and the like. Seems to me a thermal transfer or radiant coating would help cooling as well as possibly look good and prevent corrosion.

Thermal dispersants can be found here. http://www.skperformance.com/ceramic-finishes.htm

Christian

Thanks for the link to SK Performance. I sent them an email asking for help selecting an appropriate product for a Porsche engine case to prevent corrosion and transfer heat. I'll let you know what they advise.

Corrosion is a big problem on aircraft especially on the magnesium parts. I used Goodson Last Blast paint on my 69 912 902/16 magnesium 5 speed because of the pitting that had started after 35 years. Regarding "cooler at altitude" it is colder but the air is also a lot thinner and much less able to pull the heat away from the cylinders, thats why your oil temp always rises with altitude as the air temp drops, hmmmm funny thing aint it? Oh, and that big propeller is only there to keep the pilot cool!!!!! just watch how fast they start sweating once its stops.

Craig