Hi all have just recently brought 2.2 vectra cdx (2001)and have basically 1 main problem...new cylinder head has been fitted (dec) by car dealer ran car over a long trip of approx 300 miles and ok ,shortly after engine overheats,took car to local garage who flushed system out etc after testing for gasket leaks etc all ok,they said lots of what looks like rad weld came out of system and gunged thermostat up..fitted new thermostat cured it for a bit but no heating from heater,then went again a week later took back to dealer (not vaux)who done all above again,ok for a bit then took on long journey overheated again, getting peed off with this as car is in garage longer than i have owned it when it does over heat one side of thermo stat is hot other side is cold (radiator side)question is Is radiator cream crackered ?/ blocked or water pump failing ???..second question engine has the modified nut fitted re cam chain but engine number is TA 0298etc which i beleive is made in the states is this one of the effected engines that has been modified/ or was any problem associated with american built versions..many thanks in advance