with engine cold see you have coolant in radiator /expansion tank.
Check out the operating temp(gauge) is normal.
After running engine for a while feel (careful here) both the top and bottom radiator hoses.both should feel hot plus/minus small difference.
Hi, has the cooling system been disturbed? If so you have an air lock in the system, if other, thermostat faulty, Is the controls in the red area? ( Sorry to say that but it has been known).