68 hemi aluminum waterpump housing.

BillGrissom said

Many products say "don't use on aluminum" so be careful. Citric acid works well on similar deposits in radiators, and I think is safe for aluminum. Active ingredient in Prestone SuperFlush. I bought 5 lbs on ebay (cheaper). Leave soaking in the sun since heat helps. You could let your engine do the work, just install the pump, then flush in place. I always put a screen inside the top hosee until I have flushed all the crud.

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I did do quite a bit of searching on this before I posted my problem and you are very correct.
I would say 99 % of the rust removers I read about are not to be used on aluminum.
Even the naval jelly I used that did do a very good job where I could reach said right on the
label not for aluminum. I was cautious with it at first till I seen it wasn't doing any harm.
It was a slow cleaning process and I didn't see any kind of a reaction like you would expect
from a acid. Gave it a try because I had it here already.