Voltage in coolant - what is normal?

[Frogdude]

2004 A4 1.8T Quattro: Every winter I end up putting in a new heater core. They get plugged and flushing doesn't restore full heat. I've done a full flush and changed coolant about every other year. Some google searching suggested that a poor ground connection could cause the coolant to be used as a ground, creating electrolysis at the heater core leading to scaling. I measured mine by putting the negative lead on my multimeter on the negative battery post and the positive lead in the coolant reservoir. Measured 0.14V. Is this high? I checked the engine block to frame ground strap and it seems okay.

Thanks

[EuroxS4]

Your issue is within the coolant pipes and hoses that have scaled built up on the walls of the pipes and not electrolysis, the use of non distilled water is the main reason along with all the build up of scale on the walls of the piping in the cooling system. You need a citric acid flush that benz sells with boiling water run through the system. We just had a thread on this subject last week I think it was please take a look in there.

Also in order to achieve best results for electrolysis it needs to be between2-4volts.

[Turbo510]

That electrolysis issue was figured out long ago regarding liquid-cooled Aluminum aircraft engines. Conductive jumpers were installed across hose connections to minimize this effect.