OK, I'm at the end of my rope. Hope someone out there can throw me a line. 2001 Wrangler - 4.0L 135K miles. When I start in the morning, oil pressure normal (40 psi on dash), as soon as water temp reads 200+ oil pressure caves in to ZERO and "Check Gauges" light comes on. I've changed: Sensor - Harness. I've added a manual oil pressure gauge (thinking maybe the dash sensor was less than wonderful), manual gauge reads just over 25psi when cold and less than 10 when the "Check Gauges" light does it's thing. When the light comes on there is no knocking or any other unpleasant noise coming from the engine, it justs idles normally. I'm guessing I'm going to have to drop the pan and check/change the pump. Anyone have any ideas why this only happens when it gets to normal temp? I'd think if the pump was the problem, it would always be a problem.