If it's leaking it will leak period especially with 150 psi behind it (cylinder PSI). It's not going to come and go if it's a head gasket....IMHO.... If it's a small head gasket leak then it wouldn't seal itself off then brake free every 6 to 8 months. That kinda PSI would blow any small mineral deposit out-the-water.


I think he needs to check his T-stat or transmission inputs to the radiator first.