Valve lifter noise 1995 M50TU

[Scott C]

Well, finally got a chance to measure my oil pressure as a means to identify why my lifters clatter so much at idle when oil is warm. At start, the oil pressure went up to 60psi. After it was up to temp, the oil pressure (idle) was under 20 and close to 15psi. Bentley says 7-28 psi is "normal"

This clatter is really prevalent when the car is hot and oil pressure below 30psi. I have tried several oils (ran mobil1 0-30 for a long time) and now run castrol dino 20w50 but no help on this situation. Yes, the oil level is correct. I suspect that the top end is not getting the oil flow it needs.

Next step is to remove the pan and check for obvious oil/sump issues. Does this sound like it is worth replacing the pump if I find no failed gaskets in pickup to pump connection?

Thanks,
Scott