New engine running HOT

If you drill that thermostat before it goes in you won't have trapped air and burping problems any more.
That sound in the cooling system definitely sounds like air bubble hot spots.

Something a lot of people don't realize is that a hot spot can develop well before the engine is warmed up by what the gauge says, and cause a loop where it never gets it out of the engine because it vaporizes the coolant causing even more bubbles in the block before the thermostat ever opens to try to circulate it out.

Putting a 1/8 hole in the thermostat housing solves that for good and forever.