Cleaning Cast Aluminum, Enlighten Me.

I'm doing a restoration on a car that's engine doesn't need rebuilt. But I would like to restore the look of it. It has an aluminum block that is pretty nasty. I've used engine cleaner and several other solvents, but the finish just won't come back. I don't want to blast it or paint it, I just want the original finish to come back. Anybody know any tricks?

Have you tried the purple cleaners?

Spray on, let sit 5 minutes, then hose off.

Yeah, it helped but didn't do it.

Zomby woof wrote: Have you tried the purple cleaners? Spray on, let sit 5 minutes, then hose off.

If your to have any luck with these kind of cleaners dont let it dry on the aluminum at all or it could look worse. Ask a local marina what they use to clean pontoon boat hulls. Its acidic stuff not shure what my friend uses.

I've had some success with first using Purple Power cleaner and degreaser and then power washing to get most of the heavy oil and grease off. I then using Eagle One Etching Mag Cleaner.

The Eagle One is a acid that when srayed on foams up and is then rinsed away with water. It was made for cleaning rough cast raw aluminum/mag wheels and not for painted surfaces. Once rinsed off and dry the aluminum is cleaner and brighter but not the same as bead blasting.

A bit a caution is recomended here as I have only used it unassembled aluminum parts and have no idea how it may affect gaskets, rubber, etc.

IIRC, Super Clean attacks aluminum pretty fierce. Cast iron, no problem.

If you have all the grease and whatnot off the motor now and just want that fresh casting look, try to find some acid-based mag wheel cleaner. With all the clear coated/plated/polished wheels out now it's harder to find, but cleans cast aluminum parts nicely.

The Eagle One cleaner is good stuff. Make sure you get the kind for raw aluminum, not the kind for clearcoated wheels which isn't nearly as strong. NAPA also sells a raw aluminum cleaner that works well. For either one be careful as they are strong chemicals - use outside, wear gloves and eye protection, etc.

In reply to stuart in mn:

Is this a cleaner that requires rubbing? Because of the intricate shapes and gussets in the block I ideally need something that you apply and then hose off, or at least requires minimal scrubbing.

Cheap oven cleaner maybe ?

In reply to TRoglodyte:

This will strip the finish off a Mag Light. Be cautious.

bravenrace wrote: In reply to stuart in mn: Is this a cleaner that requires rubbing? Because of the intricate shapes and gussets in the block I ideally need something that you apply and then hose off, or at least requires minimal scrubbing.

It will work without scrubbing, but it works better and you get faster results if you do scrub the nooks and crannies with an old toothbrush.

pilotbraden wrote: In reply to TRoglodyte: This will strip the finish off a Mag Light. Be cautious.

I have used it on cast iron blocks and it will peel paint, to caustic for aluminum? I used the dollar store cheapo stuff.

Oven cleaner is probably not a good choice for aluminum.

I've heard that degreaser + spraying it with a steam cleaner works well, no firsthand experience though.

Stay clear of simple green, I have seen some awful damage on airplanes. Where it does not get rinsed away it keeps on eating the metal. I have heard of an aluminium safe variety of simple green, but I have not seen it.

Since aluminium oxidizes so fast in my world, is it covered with a sealer or something at the factory that makes the apearance uniform? Is there a mold release agent embedded on the cast surface?

Soft brass brushes, wire wheels, emery all leave distinct and not similar finishes.

Spoon all the goo off, get in there with a nylon brush and mild detergent, then cap it with spray clear?

Please let us know how this story ends.

Dan

The Purple degreasers are pretty strong alkalis and do a great job of cleaning stuff, but they leave the surface pretty chalky. The acid cleaners bring back the surface---but nothing beats beadblasting followed by a clear coat.

In reply to Per Schroeder:

Is there a beadblasting media that leaves a smooth aluminum surface smooth? I don't have a problem doing it, but everything I've used changes the surface texture dramatically.

Glass bead has a much more consistent "look" than using sand, walnut shells are used, some use dry ice cleaning.... I guess the factors are where is the ally, and any state of tear down ?

Of course pressure and tip diameter may play a large part of "Pattern"

I've walnut shell blasted when I wanted clean without actually changing the metal.

I work for an aluminum foundry and typically we grit (steel) blast castings to a uniform bright finish before going to the customer. For smaller parts that require a uniform finer finsh we blast them with glass beads. However, aluminum oxidizes/corrodes rather quickly to a light gray finish which actually protects the aluminum from further corrosion. As Per mentioned the only way to stop the corrosion is to paint with a clear coat or the more permanent solution is to clear coat anodize which provides a nice hard finish that resists scratching. Magnesium castings are sometimes acid dipped to get a nice uniform finish but corrode even faster then aluminum. Aside from blasting an acid etch will give you a clean casting. I have found the Eagle One etch at Advance Auto.

pilotbraden wrote: Stay clear of simple green, I have seen some awful damage on airplanes. Where it does not get rinsed away it keeps on eating the metal. I have heard of an aluminium safe variety of simple green, but I have not seen it.

I've been using Simple Green for a couple years and haven't had any problems using it on aluminum. I've used it on heads, blocks, intercoolers, etc. I sprayed it on an SRT4 intercooler and went inside and forgot it for about an hour. It had dried on so I sprayed it down again, washed it off and it was fine. I wonder if the alloys used in aviation grade aluminum make the difference.

Where can you buy glass bead or crushed walnut? And can I shoot in my sand blaster>

Glass beads for sure and I think walnut at Horible Freight.

Really!? I've never seen anything like that at mine, but maybe I've just been looking in the wrong spots.

And I can shoot it in my regular sandblaster? I don't really see why not unless there's a tip diameter issue.