[hotrodcbx]

I had exactly the same thing last year on a rebuild with a new melling oil pump. Oil pressure was fine but after a few starts I had no oil pressure at all. Dropped the pan and removed the oil pump only to find the pump drive shaft had snapped in two. The oil pump itself had no binds at all. it must have been a weak shaft from the factory although the break was clean. I installed another oil pump (not Melling) and everything has been fine since.