Quote Originally Posted by lowslowbenz View Post
What would be costly to replace?
The radiator (depending on your car) and perhaps a top overhaul. That and it can make for a really bad date.

The radiator is normally just circuited to the engine via the coolant and its corroding because Aluminum is lower in the activity chain than that of other metals in the engine and has a relatively smaller mass in ratio to the surface areas exposed.

Otherwise, its pretty isolated electrically especially if it also uses plastic tanks. Unless it has a sensor attached to it, and that's "grounded" or to avoid nitpicking confusion -the source of stray voltages.