Packard Forum Index » Pre-War (1899-1942)

Does anyone have any suggestions as to how to restore the bright silver aluminum finish to my 1929 Big Eight crankcase. While it is in good condition, it has turned a dark gray after all these years. I have had it cleaned in a high pressure hot cabinet and have had the exterior further cleaned with plastic beads, but the dark color remains. I have experimented with the tappet covers by glass beading them and they come out shiny silver. Don't want to subject my crankcase to glass beads, though.

Jim W.
'29 640 Phaeton

Eastwood has a product they claim duplicates an original cast aluminum finish but don't know if it works or would be appropriate for your situation.

eastwood.com/catalog/product/view/id/4672/s/ew-aluma-blast-set/category/247/

A BRASS bristle wire brush in a drill motor or other suitable power device will make it look like brand new without harming the Al.
I don't like to use acids but there is a generaly available acid at hardware stores used to clean AC units. Can't remeber the name of the acid tho. WARNING, the acid gives off EXTREME fumes!!! If i get a chance i'll go look at my bottle of it for the name or someone else will probably know it and post here.

I've found that the BRASS wire brush is faster and better and easier than the acid.

Have you tried an aluminum polish? Aluminum will oxide like most metals. Look at a new aluminum light pole, then compare to the older ones. Same process.

So periodic polishing will be needed to keep it looking like new aluminum. If the oxidation is light, then a manual application of polish may be all you need, but if it real bad, then you may need to use an powered polisher. Eastwood sells various polishes and application tools.

Also your local auto parts store may have aluminum wheel polish that should work for keeping it looking good after your initial cleaning.

I believe the correct finish is a "fresh cast aluminum" look as opposed to a shinny polished look.

I never even worked on one of those cars, but I seem to recall, from a long time ago, that Bill Hirsch Auto had recommended using their aluminum engine enamel with a brush-on and wipe-off technique, but you should verify/clarify that with them.

Have you checked The Eastwoood Company's selection of detailing paints? They have quite a variety of metal finishes - if you have a good idea of the appearance that you're trying to achieve.

Muratic acid. about $6/gal here localy at Hardware store. Gets abit expensive. Doesn't go a long way.

In some cases such as air cooling fins the wire brush is not conveient. On such parts i use the Muratic and a hand BRASS wire brush.

There is always a few very difficult areas in any project to clean. The Muratic acid and the BRASS wire brush usualy under power if possible will do an excellent job.

Quote:Muriatic Acid is Hydrochloric Acid, see the Safety section in the link. I wouldn't be using it!

I have run across this in motorcycle restoration. The best thing I know of off the shelf is Krylon, dull aluminum in spray can, or as HH56 mentioned, the Eastwood cast aluminum spray. I have a feeling the Eastwood stuff is a bit more durable. The trick is cleaning all the oil, etc. out of the rough cast surface. As PV8 mentioned a brass brush is better than steel, steel makes the aluminum look gray. I have personally had the best luck with stainless steel. I have used a stainless steel brush on fresh bead-blasted aluminum to give it that freshly cast look again.

As far as polish, this works great on die-cast aluminum, or cast aluminum that has been sanded and polished, but is not so effective on roughcast parts like the early crankcase.

Maybe Mal can tell us what Wade used on Big Red's 320 crankcase? It looks great!

Best of luck,
Jim

I've good results using hi temp clear coat on AL parts.