Originally Posted by AutoGear
Only thing I'll add is if you get a pump and wonder if it has the billet or Powdered Metal (PM) gears; put a mark on it with a felt-tip pen. If the mark fades away, its Powdered Metal. Nothing wrong with PM in the correct application, however if you put any trash through the pump, it can break the gears, where a billet gear will probably chip a tooth and pass it through.
I haven't seen a PM one in awhile but, it sure is nice of companies being forced to upsell you if you question their old stock having the PM gears or not. I understand that there are rising costs of manufacture; but I also know that investing in the powdered metal dies is NOT cheap at all and takes tens of thousands of pieces to amortize the cost in a reasonable timeframe
The more expensive Melling Select oil pumps have 8620 carburized billet steel spur gears. Carburizing of steel is a form of case hardening similar to austempering of cast iron. Steel billet camshafts are carburized.
Select austempering is the case hardening process used on cast iron hydraulic roller camshafts. Select austempering retains the malleable cast iron core.