Alrite guys, as the subject title says we've got overheating problems, the expansion tank was leaking so I've changed that now I've got the weirdest sh** going on, it will run sound for a while then the temperature will suddenly shoot up and the heater stops working at that point it can go up into the red for a bit and then it will drop back down and the heater starts working again.
Got me puzzled as there aren't any leaks, my next course of action (once I get some gaskets) will be to remove the thermostat and have a look at the water pump but it puzzles me as to why the problem seems to come and go, so any suggestions would be gratefully received.
Cheers