6 years and 14k miles ago, I rebuilt my 1959 3.8 (Mark IX) engine, and installed a 3.8 Mk.X crankshaft in the process. (This allowed me to use the later style rear seal.) Everything has been copacetic until the last oil change, where I found a significant amount of yellow metal in the filter. I dropped the pan, and found an even more significant amount of yellow metal in the pan. This has also been picked up by the pump, and has roached the front two bearing journals. On examination, the metal appears to be coming from the oil pump/distributor drive gear, which is badly worn in two places, 180 degrees apart (see photo).
Since this gear rotates at half the speed of the crankshaft, wear in two places, 180 degrees apart, would suggest to me a problem with the crankshaft drive gear. However, I see no visible issue with it.
I cannot recall if, when building this engine, I used the later crankshaft gear off the 3.8 MkX engine, or the original, early one from my MkIX – but they appear functionally the same.
Shaft end float for the bronze gear is .005", and the literature calls for a minimum of .003". There do not appear to be any visible clearance issues.
Would appreciate your thoughts… What am I missing?
Also, anyone got a good 3.4/3.8 crankshaft? This one might be repairable, but is scarred pretty bad from the metal intake…