6.0 ls rocker arms clatter

[Joyridin]

Where did you take the oil pressure reading? Was it down by the filter, or at the top of the engine where the factory had a sensor? I don't recall if the bypass on the pan is before or after the filter, but could you have something wrong with the pressure relief valve that is in the pan on some models and it is allowing the pressure to bleed back into the pan? This might give you a good reading at the bottom of the engine, but a low reading at the top.