I live in Pa.
I used a carefully formed sheet of aluminum foil to make a plug, with some excess coming out, so that it couldn't get sucked into the bypass hole, and not enough to block the flow of oil into the filter. The spring is still in the hole, which also prevented the foil plug from getting sucked in. I pushed the foil plug into the hole a bit, and pressed it in. During the test drive, the oil light came on, same as ever, and the clacking sounds were just the same. I removed the filter after the test drive, and the foil plug was still in the same place. I then removed it, so it couldn't come loose later.
Since there was no apparent improvement in oil pressure after blocking the bypass, it appears that the bypass is not dumping the oil back to the pan, but is sending it on into the head, or wherever the filtered oil goes. My oil press is still very low, even with the bypass plugged, and it seems like even if I spent $80 for the dealer to replace the oprv, it would never open at such low pressures, and would just act as a plug. I can plug it myself, and at least get the oil going thru the filter.
oprv or no oprv, the engine is hosed, due to wear, it seems, as so many people have said.
My last desperate attempt would be to drop the pan and check for sludge blocking the oil pickup screen or the pump. Or an oil pump bypass valve stuck open.
I've had several mechs listen to it, and have had various diagnoses. Bad oil pump, stretched chain, open clearances in the crank. One mech said the rods were fine, since he didn't hear that sort of noise. One mech said it just sounded like an old engine, and to put some stp in the oil.....
The engine has 177,000 miles on it. Oil and filter were changed every 5 to 7 K. Seems like sludge would not form under those conditions, unless antifreeze was leaking into the oil, but never was any indication of that. Never had the vanilla colored stuff in the oil. Maybe this engine just was destined not to last very long....