Bought this flathead Ford back in May of this year. It's always had low oil pressure, about 20-25# when cold 5-10# when hot. The other day I was road testing to see if my new plug wires solved my miss(they did). Had been running down the road at about 50 and slowed to make a turn. Had to wait a minute for an on coming car. When I heard this rattle from the engine. Lasted about a second or two then repeated once more just a moment later. Sounded like all the rods were knocking. I looked down at my Oil pressure gauge and it was sitting on 0. Then as quickly it jumped back up to 10#. What the he** happened? Everything seems to be back as it was but it sure startled me. My next question is can you replace the oil pump without pulling the engine?