Dissolving aluminum corrosion
 

Has anyone had any real success in dissolving the corrosion that coats aluminum over time?

I've got an (anodized) aluminum piece that is stuck inside an aluminum casting, and have been soaking the parts in PB Blaster for weeks without success It seems that either a strong acid or a strong alkaline solution will do the trick, as long as everything is well-flushed afterwards. Suggestions range from diet soda to sodium hydroxide (Drano crystals) to muriatic acid. Any stellar success stories out there?

A pic of what you're dealing with might be more helpful to show exactly what's going on .
Is this a surface corrosion like what happens on an outdrive that's been scratched in salt water ?
If my memory serves me right though , don't go anywhere near anodized aluminum with muriatic acid .

Try the CLR
Navy has been dealing with this for many years, and paint seems to be the best solution after its cleaned up.

The anodized piece is about 1-1/4" in diameter, and fits into a raw aluminum bore in the transom shield. The seal is accomplished via an o-ring. I've already decided that the anodized piece is scrap, and have the replacement in hand. Here are some photos of the new anodized part, a freshly-assembled set and 2 shots of the corroded assembly with my pulling clamp attached.

can you safely get some heat on that? outer not real thick. should heat up and expand quickly. do it while you have puller pressure on it. this is on inside of transom and you are pulling it in? any access to outside to lube and add persuasion bfh style?

I've tried heating it a couple of times, but both the shield and the offending part are aluminum, so there's not much differential expansion. (Plus, there is a 1/2" thick o-ring that seals the shield to the transom. I don't want to cook that.) No way to hit it from the inside, It's soaking in lemon juice right now, as citric acid is supposed to attack the aluminum oxide...

Muriatic acid does a good job of eating oxidation off aluminum.
VERY harsh, CAREFUL.
But it does clean up really well and my have a good chance of making down into the bore and loosening things up.
BUT...BE CAREFUL ! ! !

OK, I spent a couple hours with a syringe squirting muriatic acid around the anodized part. It definitely had an effect, bubbling away with smoke and chlorine fumes. In the end, it looks like there's a small gap between the parts, but they still haven't let go. I tried my puller again, with no luck, but I can get the part to move a tiny bit side-to-side if I whack it with a hammer. I flushed it out with water and then sprayed it down with CRC 5-56 to stop any corrosion until I can get to it again tomorrow...

Now that you have some play in it, find some of the Loc Tite Freeze off spray in the aerosol can use that. That stuff can work wonders, the longer you spray it the colder it makes the part youre spraying it on.

If it doesnt work itself, add some heat to it and then use that spray and the temp change may get them to break loose.

Have you tried turning it...sometimes that will break the sticktion. Have to do this all the time with wheel bearings hubs in aluminum sprindles. Airhammers/lomg bars/you name it...lol. Haven't found any chemicals to help yet.