[submariner409]

You need to let the system settle for a couple of days after adding coolant to halfway up in the surge tank, COLD. Then, get to a GOOD radiator shop and have them test the airspace over the coolant in the surge tank for the presence of exhaust gasses.

Cross your fingers, caress your credit card, call Jake the stud man (^^^ banner ad), and cross your fingers again. Not good symptoms.

A properly operating Northstar cooling system will NEVER - NEVER need to be "topped up".