I think I have identified something a bit unique about the 3.0 engines. I have two Dodge Caravans with 3.0 engines that have the same symptom, namely, that their oil pressure is great EXCEPT when they are hot AND under load, whereupon the oil pressure suddenly crashes. I can hear some rod bearing noise in one of the engines. Adding oil thickeners reduces this effect.

What I think is happening is that worn rod bearings pump oil out of them when under load in what bearing designers call "side flow pumping", but when there is little load, they run on the oil within them without pumping much. As they wear more, they pump more under load, sucking more oil from the crank. Then comes a moment in time when the pumping rate just barely exceeds the output from the oil pump, whereupon the pressure suddenly crashes to nil when the engine's demand exceeds the pump's output.

So what's different about 3.0 engines in this regard? I don't know, but likely culprits include:
1. A wimpy oil pump. Are higher output oil pumps available?
2. Excessively large oil feed holes in the rod bearings, allowing them to completely hog the oil supply.

I haven't torn into these engines yet, so I thought that perhaps someone here who has worked on these engines might have some reflection as to what to do. I suspect that just changing the rod bearings may fix these two engines.

Any thoughts?

Thanks.

Steve Richfield