more HG problems

Well I've changed the head gasket on my 1.8, starts and runs fine. temp gauge shows nornal but its getting real hot. when I switch it off I can hear the coolant boiling and bubbling into the expantion tank , oil seems to have fine bubbles as well . There seems to be a steady flow of coolant through the expantion tank, but how can you test the water pump?. external thermostat is fitted, pump and new thermostat are only 9 months old so should be ok I hope.
Help Please
dave

sounds like an air lock, did you bleed it from the 8mm bolt on the metal water pipe? if you only bled it from the heater hose, there will be an air lock in the metal pipe, this pipe goes into the back of the water pump.

the bleed screw is an 8mm bolt under the air filter box, take the air box out for access.

Thanks clutchdust. I did bleed both points, not well enough it seems. did it again and all ok at the moment