What kind of citric acid and where did you buy it?

Orange would smell best but I am sure white vinegar, that is used for coffee pots, works cause it stinks!

Since drinking moon shine from radiators is not good. I know there must be some safer stuff and still not drinkable. (:). A gallon and some caps or plugs sounds like a good plan to me. Heck, just leave the hoses standing up is even easier. I just to got think like my uncles did, in between runs that is! (:)

This citric idea sounds better than trying any of those commerical, hazards materials type, Prestone products! They're have words I cannot pronounce!

Those boys play Rocks and Sissors with a fourth element. Industrial Acid, it wins every time!
That's using East and West coast rules together. I got the last part that off the NCIS Los Angeles T.V. show.

To the original poster:
As far as checking a radiator, I only know of a flow test at a radiator shop and you have to trust them not to have another agenda of selling radiators. I try to watch the flow test, as I take it to them in my hands.

As long as it works and the fins are not rotting away from salt spray, its ok.
I worried about plastic radiators and got rid of the two of mine. I have a spare metal one, in the wings!

If you have an aluminum and plastic cap radiator, you will want to lose it like a bad habit.
You never know when the hose necks will crack. When you will see leaky crimps on the end caps, start writing a check!

Phil