alright, this may be a stupid question but im going there anyway, i've replaced the thermostat housing, ran the engine for 15 min with cap off radiator to get air pockets out. but after 15 min the water pumps out of the hole on top. is this normal? its still overheating around 15 min of idling. ive done this process 4 times hoping to get all the "air pockets" out. i cant tell if this is waterpump issues or coolant seal issues. any advice would be greatly appreciated.

 

Just had the same issue with my cooling system. The upper rad hose got super hard and the pressure kept blowing the overflow cap off. Turns out one of the o-rings inside the engine failed causing combustion to leak into the cooling system. I got a new radiator after the old one blew to bits. Long story short the new radiator has reduced some of the pressure, but we might be in the same boat of having to do a complete engine rebuild.