0320 Anodized Engine

[hammer408]

I'm looking for feedback - pro's and con's - regarding purchasing an anodized engine. I'm not sure if I should go that route, or if I do purchase, maybe I could paint it myself.

Any input appreciated

[Paul K]

I've read in the past that anodizing can change the structural qualities of aluminum. Don't know if that applies to engines but would be interested to know. Others with more knowledge should pipe in here!

[deek]

I've never heard of an anodized engine. Castings generally don't anodize well.

Perhaps you mean alodined cases and cylinder heads?

[krw5927]

Anodizing an engine case would generally mean that both the inside and outside of each case half would have an anodized surface. Some questions I'd be inclined to ask would be what type of anodizing has been done (chromic? sulfuric? hard anodize? some other electrolyte?), who did it, to what specification was it performed, and what was done to the case afterward.

Different types of electrolyte can have different effects on fatigue properties. Additionally, anodizing grows an aluminum oxide layer both into the surface of the part and outward from the original part surface simultaneously. This can change things like bearing and rod bores which may need to be machined after the anodize process.

One other concern might be the dielectric properties of the anodized surface. Accessories like starters and alternators are grounded through the engine case. Only surfaces which are machined to remove the oxide layer created by anodizing will have sufficient electrical conductivity for things like accessories and ground straps.

In general, this doesn't seem to be a common practice in engines. Probably for a number of reasons. Be very cautious here.

[longranger]

Maybe its alodined rather than anodized. Alodining is recommended in the overhaul manual on the Continentals I've worked on.

[fixnflyguy]

As others have said, make sure its not just alodined, which is very common..I have rebuilt several, and all are alodined...gives it a nice gold color. I do my own alodining as preperation for paint , or added protection if remaining unpainted.

[hammer408]

My error........the 2 manufacturers state that their engines are ALODINED, not Anodized.

So, with that being corrected....I still pose my question.....

Do or should I have an alodined engine painted or am I OK with purchasing an alodined engine and need not worry about corrosion OR is a painted engine the best choice?

thanks and sorry for the confusion

[Sid Lambert]

The lighter colors show leaks sooner. That may be good or may be bad.

Other than that there really isn't much difference between paint and alodine. I've read conflicting things on whether dark paint helps cooling or hurts it.

[Mike S]

Either one should be fine---------whatever makes you happy

[krw5927]

Alodine is a very effective chromate conversion (corrosion inhibitor) for aluminum. I would have no problem buying an alodined engine, though I read somewhere that Lycoming has proven a thin coat of paint may aid a small amount in heat rejection.

Personally I quite like the look of an alodined engine.