Radiator under constant pressure?

[1legjerry]

Originally Posted by cad

I had that issue and it was electrolysis. Put an ohm meter in the water and see how many volts you have.

This is correct. Make sure your radiator is grounded to the chassis. You could also have a issue with a chemical reaction with any additive you may be running in your coolant. I would do a complete flush and add only water.