The only problem related to headgasket replacement on the 1ZZ is poor workmanship by the mechanic doing the job, not working to specs, not checking tolerances and stuff like that.

As for reboring stories, those probably have nothing to do with headgasket replacement, more to do with the early 1ZZ engines that had oil consumption issues.

 

there should be NO boring involved in head gasket replacement. why are you changing it in the first place?

 

replacing it as had car to garage today, done a sniff test from expansion tank, water turned from blue to yellow/brown, head gone or going!

oh well, looks like i will be staying in for a while.