Thanks for the great post and pictures Paul! It sounds like our engines generate the same pressure, so I am not worried about running pressures.

As to cold, you could still be right. The lack of cold symptoms, may simply be a case of viscousity masking the problem. The thicker oil could prime the pump/gallies quickly enough to minimize the problem.

The check valve is interesting idea, as I didn't know they had one. I am using a parts store filter right now and used parts store filters before the rebuild(mainly WIX). Immediately after the rebuild I used an Isuzu filter, but I changed oil so quickly after the rebuild, I never noticed if I had this problem or not. Currently I am using a parts store filter because I had one left over. In the future I will be using only Isuzu/OEM and the two I have in stock are from Jerry Lemond and are Isuzu/OEM. So the filter idea is conceivable since I only used one filter briefly that would be absolutely correct and wasn't a cheap immitation.

As for the regulator you mention, My valve had a small scratch on it. The scratch was clearly older though and it was not what I would consider a "significant" scratch and prior to the rebuild it performed its' function just fine. It moved within the bore without a problem. The scratch could indeed leak hot oil past it though, as I was too ignorant about these engines to consider this as a something that could be an issue. This might actually be my culprit.

Thanks again Paul, I really do appreciate it!

NCDiesel