Bleeding cooling system??

Hi there, Im new to the forum, my mate has a big problem in bleeding the cooling system on his freelander 1800cc after changing the head gasket,Done every thing by the book but still got a air lock.
Driving down the the road with the heater seems to be working fine {HOT} fan cuts in at the right temperature then the heater turns cold can you help??.

CHEERS



MAS

Hi mas . . .you've got the dreaded pig of a air lock,check out in search, coolant problem, thats an old thread, it will tell on how to make a header to clear the air lock , and remember if you've got a small leak or a loose hose in a high place this can reintroduce air,so ya might clear it only for it to come slowly back again,i know cos Ive had it, anyhow best of luck. . .ming