I recently found my block was extemely rusty after relying on water wetter for corrosion protection. I looked for a way to find the old dupont 2 part block cleaner-now unavailable because of EPA.
I found oxalic acid sold as DAP wood bleach at any hardware store is the ingredient they used. Neutralize it with arm and hammer washing soda NOT BAKING SODA.
Mix 9 oz oxalic acid with a gallon of warm water,pour in and warm engine up to 160 or as hot as you can get it. let sit for one hour. flush and neutralize with 2 oz of sodium carbonate (washing Soda) mixed with water.
Oxalic acid only dissolves rust and is harmless to steel,paint,and anything else.
Here is a link to a long thread about this. If you read down you will find the GM service bulletin for corvette radiator service.
http://forums.corvetteforum.com/c3-t...ner-flush.html
Wood bleach is cheap to buy. Try soaking a rusty part and see how it comes out. I did a rusty axle nut before i used it in my A.
Here is a good tech article on the HAMB with amazing pictures.
http://www.jalopyjournal.com/forum/s...ht=wood+bleach
John