I doubt this has anything to do with boost, but since its a boosted B18C in my DA, figured I would post here...well anyways I had issues with my overflow filling up and not going back into radiator...I replaced HG and put in a new set of ARPs to be safe. So I replace the tstat and rad fan yesterday after still having issues...I had a small coolant leak and FINALLY the overflow drained overnight. I think it was the rad cap. My question that I was leading up to, is I am bleeding the system with a Lisle funnel...when the car is idling (my idle is 1.5k lol) there is NO bubbles. When I rev the car up, high, I get a small amount of bubbles and a small "burst" of coolant...is this normal? Cavitation from WP + extra coolant being pushed because of RPMs? Or DEF HG / deck issues? Please tell me exactly what I should see in this scenario so I can properly diagnose. WHAAT EXACTLY IS NORMAL?...thanks in advance!

 

my turbo gsr's cooling system is going crazy too, have you checked your intake manifold gasket under boost it might be blowing into one of the coolant passages... well thats what people were telling me to check, good luck figuring it out im about to give up on mine and send it to a shop

 

Sounds like your head gasket is on its way out....
https://honda-tech.com/search.php?searchid=7781528

 

Update: may be fixed...took it for a 1+ hour cruise and next day checked and the overflow had nothing extra and no coolant missing, save for a couple teaspoons...might have been a faulty cap after all but I will definitely know after a couple more times driving it...i really hopse that was it.