I've been ridiculously busy lately but this week I made some progress. I pulled the water pump housing and the part number is 3698468, which came on 73-78 Mopar big blocks. I was kind of hoping that it had an after market housing that was the culprit but that doesn't seem to be the case. The big ports were clear/clean.
How about the water pump? Can you describe the type/condition of the water pump?
It's a brand new pump but its a cheap cast parts store unit.
