Beware of Electrolysis…

[PrerunnerRob]

Electrolysis isn't necessaraily being caused by the ground issue. Anytime you pass a fluid through different metals the are coupled together, you will create a slight electrical charge, causing the damage you see over time. Even an aluminum or copper waterneck on a cast iron block will do the same, but there is a radiator cap that has a sacrifical anode that will give itself up to combat this. I believe it is called the "rad cap" and I think summit sells it. You can check for this by using a sensitive digital voltage meter, grounding one side, and dipping the other into the coolant.
When pipes are fit together of differnt materials(in building construction), a dielectric union is used that seperates the two materials with a washer or seperator made of plastic or rubber.
I'll see if I can find the radiator cap I was talking about and post back later.
Good luck!