Frank Grunthaner wrote:

> Sorry guys, the water can and will close the circuit. As I said before, the
> question is only how much and how effective the surfactant package is at
> reducing the
> level. Aluminum will corrode, as will the copper. Complex reactions, local
> chemical variations, oxide formation-insuced changes in potential. Main
> impact will be slag formation.
>
> Answer is corrosion inhibitors in fresh antifreeze.
>
> Frank Grunthaner

Yes, corrosion happens.  Certainly different spots on the same piece of metal
can serve as anodes and cathodes so that redox occurs.
  I am trying to address the question of whether we *increase* the rate of
corrosion of aluminum engine parts by using copper in other parts of the
cooling system ( long pipes, double T, radiator, etc.)  In these cases it seems
to me that it may be relevant to ask whether there is an electrical path thru
the chassis.
  In the classic electrochemical cell ( two different metals in an electrolytic
solution), there is assumed to be an external electrical connection from one
electrode to the other.

Larry A.