Status and question
I have flushed the radiator with a diluted Simple Green and distilled water solution. I ran the engine for about 5 min. The block was getting hot and the large hose was remained cold.
I have since rinsed the radiator core with more distilled water and will drain again. Waste water was pretty clean. No large about of dirt or metal (none).
Question
How can you tell if the over heating is thermostat or water pump? This is a relatively new water pump with very few miles on it. Replace when engine was rebuilt 6 years ago.