overhyating but not because bad thgerm. 9or pump new radiator

Hello, I apologize that it's difficult to know what you mean by your words, as they aren't clear. But, a temperature gauge at "2/3" doesn't mean overheating. It could mean that it's normal and the gauge reads high. Besides that, you'll want to make sure your cooling system is full of clean coolant and no "gunk" as you've described. I'd definitely recommend a full flush of the system and perhaps even replacement of the thermostat. That's a good place to start.