hey guys im new here been reading a lot of advice as a guest here is my problem my 99 needed new head gasket so i replaced and did also replace heater core,water pump,radiator,t stat fan clutch,now when it runs it will go up to over heat,so i checked t stat and noticed no coolant in upper hose so i ran with out t stat and coolant flows to radiator i tested t stat and it opens,put it back in same thing any ideas thanks in advance