12 volts in my radiator ???

[vance.dykes]

this is a little long but it so simple that you will win money on a bet .. i have . do it a few times and see what people say.

 

[toolmanmike]

Flush it. It is producing acid.

 

[Ernie ingling]

Coolant way past needed flush. Used this test for coolant for many years.

 

[RJRENTON]

I believe the phenomenon is called galvanic action. It is caused by the reaction of the coolant and the probe immersed in it, due to the acid present. You can also measure the acid concentration by checking the pH of coolant. pH = 7.0 is neutral. pH less than 7.0 = acidic solution, pH greater than 7.0 = alkaline solution. pH means the parentage of hydrogen ion concentration in the solution being measured.
The coolant has lost its corrosion properties....change the coolant...flush the system to neutralize any acids present.....refill with new coolant of your choice to at least 50% concentration. The acid (weak carbonic acid) develops over time due to the dissolved carbon dioxide in the air and water and the heat/cool heating cycle during operation. Just thought you might like to know the chemistry involved.
BOB RENTON

 

[Jc cooper]

Good to know, I always enjoy your educated views on issues, a lot to learn, if we have eyes to see and ears to hear ! Thanks AWS -CwI