I did not find anything in a search. I am trying to figure out the coolant flow of the AST. Does coolant actually flow through it? Or does it only absorb the air bubbles with a minimum amount of coolant (air trapped in coolant bubles)? Does the line running to the rad, does that just push the "hot" coolant back through the block?

Would it actually be more benifical to have a line from the AST at the top of the rad as well? Cause the air would be trapped in the top, not the bottom.

 

Coolant needs to circulate through the AST, which provides headspace for small bubbles in the coolant to separate out. If there was no return line, once the AST was full no more bubbly coolant could be "processed". Stagnant coolant would just sit in there.

I'm sure the return line to the bottom of the radiator is a fluid dynamics thing to ensure it circulates, but not my area of expertise. Air is not removed from the bottom of the radiator. Air in the radiator should propagate up to the filler neck (high point of the system) and be forced from there to the AST