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

For about $100, I have had good success with cleaning the crankcase in a hot detergent wash cabinet that most machine shops or motor rebuilders have.

Jim Wayman
640 Phaeton

Actually the cylinder blocks on these engines are iron, not aluminum. The crankcase and oil pan are cast aluminum with a somewhat stippled, non-reflective surface as supplied by the foundry. Packard left these castings unpainted and unpolished. Over the years a coating of oxide forms on these castings that darkens and dulls the surface. It can largely be removed with drill-mounted wire brushes with the engine still in the car. The wire brushing will leave the castings with a brighter but certainly not a polished-looking finish very much like newly-cast aluminum. Oxide will begin to re-form on the surface although it could be some time before it is highly visible. To prevent or at least slow down this oxide process, something like Eastwood's Diamond Clear finish for bare metal can be sprayed on the castings. I've seen a 1930 726 engine done this way, and it looked more authentic than the commonly-found aluminum-painted restorations. I wouldn't put any kind of coating on the inside of these castings.

If you are polishing a piece of aluminium - not necessarily as large as a crankcase, steel wool and soap is a good way to achieve a good finish. Rub the steel wool (moistened with water) onto the bar of soap and apply to vigorously the aluminium. Deep scratches and marks will need to be dealt with before polishing. It is better to keep the action all in the same direction as you would when using sandpaper. When the surface is polished to your satisfaction degrease it with some solvent and apply a clear protective finish.

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If a coating is being considered, here's one that works, is permanent and has heat dissipation properties.

finishlinecoatings.com/misc.htm

finishlinecoatings.com/

I had my manifolds and exhaust system done in cast iron and stainless steel (simulation). If you look at the other finishes they show online, you'll see chrome-likeand aluminum-like ceramic coatings. They coat the inside of pistons with one coating and the outside of pistons with another, on land-speed record cars. They know this stuff.

This picture was at 8,000 miles on the Duchess, but at 10,000 miles now and it looks no different. It stays looking new. Check it out.

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