Yeah the housing was in great condition, cleaned it all out and tested the stat, then put it all back together, filled it up as slowly as possible to avoid air locks, but still the issue is there, I renewed the coolant as well, but the bit i dont understand is, there is no "mayo" in the filler cap, there was no oil in the old coolant what so ever and I flushed the system when I changed the pump over which showed in the good condition of the coolant that I took out today, the only other thing i can think of is maybe try some of that K-seal stuff as appaerntly it is good for any cracks/leaks in the coolant system. Any thoughts on that? I dont really fancy going down the route of a new headgasket etc as I want to swap a 2.0l in there when I have a bit more saved up in the coming weeks.