I have had, what seems like a valve train knock, after my head gasket replacement 4 years ago. I thought it was the vane pump gear knock (could be the drive gear). I diagnosed the vane pump knock by when I turned the steering wheel to lock the knock would go away so I just replaced the vane gear (OEM) and a rebuilt pump(NAPA) but the knock continues and goes away after wheel lock still. Opinions or suggestions before I rebuild the engine.