Re: Big Problem!!!
as you said mate, it prolly just shock up all the crap in the cooling system. Id buy some el cheapo radiator flusher and run it through or just change the water once every 1/2 tank till it comes good or take it to a radiator shop and have them do a flush.
Its also worth going through your cooling hoses, removing and blowing them out with a tap. I had some really yuck stuff in my skinny hoses comming off the heater pipe (baby poo colour and consistency).
Mods: Pacemaker extractors, lukey cat back system. DBA Slotted rotors front & back.