When you have knocking noises concurrent with a loss in oil pressure, there's something serious wrong. It's highly improbable that it's a loose rocker and a failed oil filter at the same time. I'm not saying you need a full rebuild. I'm saying you're going to need one if you don't get to the bottom of it. See pictures above. It sounds like a spun bearing to me. If it's a bearing issue, it might be as simple as changing that one bearing.
Kurt
Kurt
