2001 Sunfire cooling system

I just had the engine replaced on my daughter's 2001 Sunfire with a used engine. THe original engine got so hot it turned to junk. The replacement engine runs great but the installer can not understand why the cooling system does not circulate well. New thermostat was tried. Cooling fan runs at about 185 degrees. Engine's operating temp is about 195 degrees. Radiator was flushed. Should I be concerned?