The line doesn't have to be completely broke down to cause these issues. A ball/gate valve has 80% flow when the valve is just opened 1/4 of the way
I understand flow and pressure, but in order to suck air it would have to be broken bad enough that there was little to no pressure left on the leg going to the kitchen. In his initial description, he described the problem with the spitting and sputtering as if it was still under pressure. I can only speak from my experience and all of the leaks that I have seen in a slab either seep up through and wet the slab or there will be a wet spot somewhere coming out from under the house or both. I may very well be wrong but it will be interesting to see what he finds the problem to be...
