suggesting to purge air from system, only if the system is intact with fans are wired automatic and thermostat valve working.
if the thermostat valve and cooling fans are working on automatic, there seems to an air lock. when engine is cold remove radiator cap and insert a long tube funnel ( keef ) in the radiator filler. start engine and leave it idling for 3 cycles of engine cooling fan on & off. observe temp needle and funnel burping coolant level rise and fall. once the coolant level stabilize remove funnel and top up radiator. level off coolant in expansion tank and cap the radiator.
use caltex premix coolant.
