water overheatinh in central heating?

The water in header tank nearly explodes hot after you can hear strange noise probably from the pump. I changed the pump, drained water from the system cleaned it, tried to put some cleaning chemical stuff, not solved. 30 min after turning the boiler on water gets to the header tank very hot (steamy) and condenaste on the ceiling. I checked all rads bleeded them, they full of water, the pump (you can hear) is working nice till 30 min, after starts making noise, it is very hot.