[niles]

Try the super air purge technique;
Your fill spot should near the high spot in your plumbing, I raised my front about 6 in then filled it full and squeezing(milking) the bottom hose water and a lost of air would bubble out. Keep the cap off so you can see the water/air coming out at you compress the lower hose. It takes about 30 min of adding about 4 oz of water at a time and and milking the air out. Eventually not air /bubbles come with the water, only solid water.
The reason this is so critical is that if you have a small air pocket it your head, example, .5 cubic inches and it creates a hot spot on the metal head that exceeds 212 or 230 deg(presure cap); then the water flashes when it hits the hot spot and creates 20-30 times that volume when it flashes to steam and forces the water into your purge tank and the cycle excalates and gets worse.
gn