pressure in the overflow thank while at idle

[chana1634]

I have a 1999 e7 350, and i notice that coolant was coming out of the coolant tank, i install a new cap, but did not solve the problem, i remove cap, and notice a lot of coolant coming out, and coolant was just warm, on the cool side, i try to bleed the system and notice air coming out of the small hose on top of tank, the start truck again with cap on, after a few minutes i notice that coolant was pushing out a lot and stop engine, when i did stop engine , i notice like a ball of coolant and air came out a lot, then bleed air again, and run engine again, after a while start doing same coolant coming out, but right then i step on fuel, and i notice that the coolant stop coming out of the tack, let it idle again, and coolant came out air build up at idle, then i step on fuel idle hi and it stop building air in the system, when i step on the fuel, coolant stop coming our of thank, I ask any body if has any  idea, please advise, p.s never seen this before, thank your, 

[Dirtymilkman]

Possibly your air compressor is pushing air into the coolant. 

[fjh]

You got the head of the engine you need to check your liner protrusion should be a min  24 the book says 22 ( that is  to low) how ever it will  work for a while on a  350 24 is  a much better place to be!