I was under the impression that these failure began to show up in high numbers in the 90s. To me that would point to something that occured after intial manufacture by Mopar.

We may never know with certainty, but if the cause was misaligned pump shafts, harmonic stresses or any other such design factors wouldn't the failures have occured from the get-go?

Some have suggested improperly hobbed gears on aftermarket camshafts, while others have pointed to inadequately hardened pump gears. I realize that it's possible that a basic design flaw could be exacerbated by later inadequacies in aftermarket parts but still It looks to me that the major issue(s) arose at some time well after the initail manufacture of these engines.

I am confident you are headed directly toward another locked thread. You are a direct supplier of self invented misinformation. Please stop.

Kevin
Two points to ponder:
1. I just removed 20 NEW oil pump gears and 5 Used Stock gears. The materials used in the New pump gears is CHEAP Grey Iron its very porous and easy to fracture. The Stock gears are a high quality cast or maybe even machined piece.

I may be on the other side of the moon with the following remarks, but first of all, my native language is not english, so I tend to express myself a little more clumsy than I should. Secondly, I cannot document what I say next - it is just one tiny bit of information that is stuck in my mind without reference to people, time or place. What triggered it was the questions about cavitation and the use of synthetic oil.

In the early days of synthetic oils, they had some problems in long-distance racing, especially under humid conditions, and probably related to cavitation. It had to do with the absorption of moisture in oil, where the old mineral oils and new synthetic oils behaved very different. An engine will produce an amount of water, and some of it will end up in the oiling system, whether you like it or not. A mineral oil can hold a relatively large amount of water in suspense, and formation of foam for that reason, surely in addition to aeration in general, created known problems. In contrast, the absorption of moisture in a full synthetic oil is nil or very low, but you still have an amount of 'free' moisture in the oiling system, and that water was thought to cause cavitation, with devastating effect on - among other things - oil pumps. One solution to the problem was to use an oil/water separator on the suction side. I wish my memory was better, because that is all I can remember. I hope it can be of help, not only add to the confusion.

One of the basic sources of information on this subject is Cavitation and Bubble Dynamics, by CE Brennen. While it may not exactly be what you keep within reach if you have trouble sleeping (hmm, perhaps it is!), it should be looked into anyway. Olaf.