green antifreeze crystalized?

[40cpe]

I recently bought this '38 Ford with a '66 283 Chevy engine. The temp wasn't coming up over 130 degrees so I was going to change the thermostat. I found hard, green deposits around the thermostat opening in the intake, like crystalized antifreeze. I remember reading somewhere that when green antifreeze gets old it silicates and is hard on water pumps. I think this is what is going on here. I looked in the radiator and can see little chunks of it in the tubes. How do I clean it without taking the radiator out and having it rodded? Is vinegar a good option for this? Advice is appreciated

[taxpyer]

I have heard of that before............  also having it "gel" and settle out in the heater core after 2-3 years.  Usually you have to flush the core out with water. Usually a good flushing cleans things up with just water. I must admit that I'm not familiar with how really old antifreeze acts.