EA overheating problems - solved
A while back I was having the dreade cycling temp gauge problem with an EA Falcon, didn't matter what I did to it (thanks to AussieBlue for all his suggestions), I still had it, I even had the cooling system pressure tested.
Well finally the head gasket blew, this motor is only 75,000k's old and it turns out the bastards who rebuilt the thing never faced the block and it was pitted near pot #6 causing water to collect and slowly eat away the steel in the gasket, finally getting big enough to fail completely.
I can only assume that the leak occured when cold and sealed up enough when the engine reached a certain temp until the gasket finally let go big time.
Anyway, caught it in time, no warped or cracked head, had the pits filled and a new head gasket, $415 all up, no more cycling temp gauge and mystery leaks in the piping.
So for anyone who has the cycling temp gauge problem, it could point to a slight head gasket leak when cold.