Originally Posted By RapidRobert
Out on a limb here but could it be electroyalisis (sp)? Someone said once about with your meter on low volt scale, one probe in the coolant & the other touching the radiator metal & over a certain # of tenths of a volt being generated that there is some galvanic action takeing place (like a battery that is causing corrosion/rusting).


That'd be my first guess also. Read this: https://www.hotrod.com/articles/keep-your-cool-preventing-radiator-eating-electrolysis/