Topic: Restoring Cast Aluminum

[KevinK]

The cast aluminum valve covers on my 88 got splashed by battery acid.  What would be the best way to restore the finish and then protect it? White stained.

Clean/neutralize
Tumble?
Sharkhide or Pig spit?

Or should I just try some Cream of Tarter and lemon juice and soaking?

[79mustangcobra]

I looked it up and a lot of people say to glass bead it and then clear coat it.

[carlite65]

i would not blast it. the texture will change. i'd try some eagle one mag wheel cleaner.

[J_Speegle]

If it (acid) has eaten into the aluminum you might hide it but the look will be different when you get done.

If you haven't neutralized it yet it might be too late.

Just about anything you do to aluminum will change the look since its very porous so IMHO always the least destructive products first.  Friends often suggest wheel cleaner and a stiff nylon brush (wear some eye protection

If that doesn't work maybe change out a local engine builder and see if they will hot tank (by itself not thrown in a bin) them

[suskeenwiske]

Neutralizing is very important. Without seeing it, it's difficult to say what to do next but start by gently rubbing some baking soda into the wound, (wear gloves). Let that sit for an hour or so and brush it clean with an old tooth brush or some other soft nylon brush. Compressed air is also helpful but needs to be moisture free; do not use Canned Air.

At this point get some Mineral Oil, any Grocery Store or Drug Store in the medication section will have it, (do not use petroleum oils), and some very fine Steel Wool, not Brass or Stainless wool. Apply a thin layer over the affected area and dip the steel wool in the oil as well. Rub gently in a straight line or in the direction of the pattern if there is one. The Steel Wool will not scratch the Aluminum; the Mineral Oil acts as a lubricant, as long as you don't apply too much pressure...try a spot inside the valve cover for practice.

Be very careful if you try Eagle One, if done incorrectly, which is easy to do, it'll leave streaks in the Aluminum and will be an enormous pain to clean up.

Can you post a good photo? May make it easier to suggest other methods, just depends on the severity of damage.

Thanks

Ray

[WT8095]

You might want to consider soda blasting it. Soda will not erode the metal nor will it leave a "speckled" surface like sand or bead blasting. It will "fog" shiny areas, though. (Only on aluminum; it will not tough steel, brass or chrome) The attached image is a closeup of a grimy old carburetor I partially blasted as a demo. The entire carb was encrusted with the grime and dirt seen at the bottom of the photo. It also works great for getting carbon buildup off of aluminum cylinder heads.

Blasting soda is sodium bicarbonate, i.e. baking soda and will neutralize the acid as Ray pointed out. For the example shown I used Armex medium grit soda. As with any product or technique, try it out on a test piece before using it on your good parts to make sure you know what results you're going to get. 

[Brian Conway]

     Interesting and challenging problem with the aluminum OE intakes and valve covers.  My experience with the early 69 big block C9 valve covers was a very disappointing round of experiments.  The aluminum material is very porous and accepts a stain quite easily requiring constant care and attention.  Not one of FORD's better ideas.  I took the same route as many others, I gave up, and just had them polished.  Perhaps one of the ' judges '  could post the MCA position on this situation ?  Brian

[WT8095]

     Interesting and challenging problem with the aluminum OE intakes and valve covers.  My experience with the early 69 big block C9 valve covers was a very disappointing round of experiments.  The aluminum material is very porous and accepts a stain quite easily requiring constant care and attention.  Not one of FORD's better ideas.  I took the same route as many others, I gave up, and just had them polished.  Perhaps one of the ' judges '  could post the MCA position on this situation ?  Brian

Impco makes impregnating sealants to seal porosity in metal castings and other materials. AlumiSeal is designed specifically for aluminum.

http://www.impco-inc.com/sealants

Loctite has a line of porosity sealants called Resinol. It appears that these all seal the pores in the metal - presumably the exposed aluminum at the surface would still be subject to oxidation. I have not tried any of these products, I am merely reporting their existence in case anyone wants to investigate further.

[J_Speegle]

....... The aluminum material is very porous and accepts a stain quite easily requiring constant care and attention.  Not one of FORD's better ideas.  I took the same route as many others, I gave up, and just had them polished.  Perhaps one of the ' judges '  could post the MCA position on this situation ?  Brian

Would expect that in a Concours class - no matter the organization (Ford or otherwise) the expectations would be to return the part to the original look and anything less would be a graduated (closer to the original the less) deduction on the final look. Pretty simple and straight forward IMHO considering the goal of the restoring. Personally at times I've given up on a set and just found better candidates

There was a point were the NOS CJ valve covers were made/finish with a somewhat polished look - and those have been deducted for in the past