Water belches from overflow tube.

I replaced all the innards this evening with a Fluidmaster universal kit from H.D. I no longer have the problem, I guess not knowing what it was is OK as long as it's fixed. Thanks for all the help and suggestions.

frank

Congratulations, Frank. Glad you got it fixed either because of or in spite of us. Since the toilet still exhibited the problem even with the water turned off, that pretty much eliminates the fill valve as the source of the problem. So my vote is for the flush valve, something to do with the flapper and the way it closed, or the design of the overflow tube.