Engine Painting (Alodine):

[SchnellSchweitz]

Ok... So I'm going the alodining route for my engine parts.

Picklex>Alodining>Painting

Any suggestions for paint type for use on alodined parts?
(Please provide brand name and color. I'm wanting to make it look original.)

If you have done this before... I would appreciate your successful exposure times for all products and dry times.

Thanks in advance.

Eric J.

[unclebilly]

I used alodine on alloy wheels for several toyota 4X4s i used to own. I think we let it sit for an hour or so before painting.

Why are you painting your engine? Have you aready painted your calipers?

[SchnellSchweitz]

I have not painted my calipers... I'm focused on the engine right now.

Reason for engine painting: I want it to look new and last. Had my engine soda-blasted a few weeks ago.... now it's time to protect.

[James Brown]

alodine is just for the aluminum, you probily have new hardware if your doing a rebuld. what color are you painting it? or you can just put the factory undecoating back on it to protect it (unless it's a race car/show car).

[SchnellSchweitz]

I'm not planning on removing the hardware. My plan is to paint the substance onto the parts and cover all hardware with 3M foil tape. I will probably coat the hardware last with a SS primer.

I want to paint it the original factory gray/silver. Need ideas on what product to use.

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[304065]

As surface corrosion treatments go, Alodine is pretty old technology. It's used mostly on aluminum to prepare the surface for another coating. The old zinc chromate (green stuff) that you see in aviation use isn't a very good topcoat, and of course contains CrVI (hexavalent chrome) which will kill you and has been all but eliminated from commercial use.

I'm trying to understand what you mean by Alodining engine parts. Do you mean the case, chain boxes, cam towers, etc? That's probably not a bad idea in respect of the anticorrosion properties, but again Alodine needs a topcoat to withstand any kind of hostile environment. It will also turn everything light brown depending on how long you leave it in solution.

It's not recommended to coat the engine case or the other parts, even though you see people here who do it. The reason is, you will ultimately get scratches and other surface imperfections that will allow moisture UNDER the coating, which will propagate corrosion where you can't see it.

I used Zoopseal, which is a ceramic sealer that fills the pores of the aluminum and will hold off corrosion for a few years. It's pretty expensive, but it won't inhibit heat transfer like thicker coatings.

[SchnellSchweitz]

Interesting.... I have read great things about treating aluminum parts with Alodine before painting. According to airplane mechanics, it won't burn off or go away. The big issue is surface cleanliness.

My plan is to prime my block, covers, chain housing, fan, fan shroud with Alodine 1201.

It seems to be a very reliable approach.... Although Zoopseal sounds interesting too.

My plan is to paint over the Alodined parts with a high-temp engine paint.

Just wondering what folks recommend here (brand/factory color)?

Krylon?

[docrodg]

If you are going to paint the engine I would recommend VHT paint. It is good over 2000 degrees. Another thing to consider is color. Black will give the most heat transfer.

[SchnellSchweitz]

Several questions about VHT Paint:

What guesstimate would you say the color black would improve heat transference (Not sure if "transference" is the right term??? Perhaps you mean heat dissipation???). I always thought black absorbed heat?

How many cans of paint did it take to paint the block alone?

Thanks for your input. This is all good info!!!

[RWebb]

fwiw - I like the Al parts to look like they are Al

in Orygun, there will not be any appreciable corrosion of your Al parts for the next 50-100 years

a black color will slightly increase radiative heat transfer when the motor is hot - you could measure it in the laboratory, but the effect is nil

[James Brown]

Alodine etches the surface causing "corrosion" to the metal then you prime and paint (as in the skin of an aircraft) and that action prevents oxygen from continuing to corrode the base metal. works good on airplane skin if you prep it correctly. There are many better products out there. Just painting it would be good enough. If the car is a 82, thats 27 years without any fancy treatment and how does the engine look? So to go through all that prep and chemicals to protect something that hasn't really degraded is questionable. I would leave it bare and lightly spray a undercoating on the bottom to prevent impact damage and use the money saved to convert to carbs!!!!!

[SchnellSchweitz]

Well... I've already purchased the Alodine, so I'm going through with it. I've spent about $45 on it so it's not a big loss if it is all for not.

... and yes, it could be it's a bit of an overkill, but I'm ok with that.

On another note, I'm thinking the VHT paint is the way to go. However, I like the silver. I don't plan to use this vehicle on the track so heat dissipation or "radiative transference" is not going to be an issue for me.

I do have to say, since I had my parts soda blasted I already see some very minor surface corrosion occurring during storage. So there may be more reason for the Alodine than previously thought. I, of course, appreciate everyone's opinion.

It all gets factored into my decision.

One question about the VHT paint... How did you cook your parts after applying the paint. The directions say you have to cook painted parts in an oven.

[James Brown]

Don't get me wrong, I think is a cool idea, it will prevent further corrosion. and it makes you happy! show us some pictures of the prosess.

[Tim Hancock]

I have done a fair amount of aircraft painting. I always etch, then alodine bare aluminum with two Dupont products (don't have the numbers handy). The etching metal conditioner is applied with scotchbrite....rinse... then wet part with alodine....rinse. After the surface prep I usually use Dupont Corlar Epoxy primer, then top coat with Dupont Imron. This is the proven method I like/trust the most, but there are other ways to go also.

I have painted a couple of showplane engines using this technique and they have held up well over the years. That said, I have also have decent results simply using high temp engine rattle cans on some 911 engine parts after cleaning then etching the parts prior to paint (no alodine used...just etched).

[RWebb]

at least silver won't look as bad as black after the road grit removes the paint in a shotgun pattern

[SchnellSchweitz]

Hey 304065... You were 100% correct about the use of Alodine 1201 on engines.

I just dug up some new data I have never seen on Alodine 1201, which leads me to believe it will not withstand the regular temperatures of an engine.

"Temperature effects on corrosion protection. Unpainted conversion coatings will commence losing corrosion resistance properties if exposed to temperatures of 140 ºF (60 ºC) or higher, during drying, subsequent fabrication, or service. As temperatures and exposure times increase, the corrosion protection of unpainted conversion coated parts decreases. The reduction is believed to result from the coating dehydrating and the resulting insolubility of the chromates within the coating."

Even though I planned to paint over my application, I don't trust something that won't stand up to these temps alone. Unfortunately, Henkel doesn't do a good job explaining this in much of their literature. Sounds like I'm going to be sending my Alodine back for a refund

I will look for the Zoopseal as an alternative... Thanks again 304065 for your input. It may have just saved me a paint job.

[SchnellSchweitz]

I just contacted Aircraft Spruce (the place I bought the Alodine from). They said I could return it... so that's great.

Thank you everyone who commented on this thread. It pays to visit Pelican for info!!!