Mine runs similar to Scotts, and I would guess air trapped in the system or replace the t-stat. Running a GM t-stat

i always use this to fill my systems

http://www.summitracing.com/parts/LIL-24610

i also have a cooling system vacuum. it pulls a vacuum on the whole system and when then you stick the hose in new coolant and turn the valve and it fills the system. it works pretty good but i like the funnel better.