Water pump engine mount 440

I did. I bought one of those spill free funnels where you can seal it off and run it with the funnel on and thats supposed to bubble out any air while the coolant circulates. Ive done that probably 5 or 6 times running it for about 20 minutes or so, sometimes it seems to stop around 190 and sometimes it just keeps creeping up. The last time i did it I saw a lot of little tiny bubbles when it was idling and if i'm not mistaken that is a leaking head gasket. But it would go away and seem to smooth out when revved. I've focused a lot on trying to get any air out because I know that could be a big culprit. But it just tests me or something because I've had it where it didn't overheat and then it did again and I didn't open up the cooling system at all.