hmm well, what i did when i did a complete coolant flush and replace was: (and i'll only recout the refilling part since that's all you need)

1) close up all drain plugs and hoses and stuff with the tstat removed
2) filled it up with roughly 50/50 coolant and water until it was full
3) undid the tstat housing and swapped in the stat really quick (some coolant came gushing out of course) - it is important to make sure the little nub on the tstat is facing UP. that is an air vent thing of some sort.
4) start up the car and warmed it up to operating temperature.
5) shut off car, and start squeezing hozes and stuff all over thus 'burping' the car
6) top off

and that seems to have worked fine. car has been running well all along for the last 5 months now.
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Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'