waterfall sound is a bad thing. the goal is not to hear it.
check out your radiator with temp gun and see if you have wildly varying temps from top to bottom

 

Thanks Dusty1, I recently had my radiator flushed before I changed the HG and the truck still overheat. One thing I noticed when I was bleeding it was the water level from the cold level rose when I left the engine running and revving the engine. The coolant will over flow out of the reservoir. What do I do now or check to correct this anomaly ?