Thanx guys, all points noted. I like you am also surprised over the Comtec as it was supposed to be GrpA type, but it might have a fault in it, as for torqued correctly that i can only say yes as it was put into a shop that deals with fast cars etc so i hope they knew what they were doing. The thermostat it a possibility but was new at the same time as the head work was done. Now iv heard that there is on the market a type of litmus paper that will show up if there is exhaust gases in the water, is this true or am i listening to fairy stories................