[robo]

An extract from an article.

Bob

The engine is so simple that it's pretty hard to assemble it wrong but despite this the one thing that few people get right is fitting the oil pump. DO NOT try and force this to line up with the sump flange. The oil pump must be central on the crank nose and NOT forced to one side. If you take up all the clearance in the pump gears by trying to align the pump flange with the sump flange then the gears will get smashed by crank vibration and pushed through the side of the pump. Fit the pump loosely and move it from side to side and up and down until you get a feel for the amount of free play between the pump and crank. Then position it as central as you can and nip the bolts up. Any error relative to the sump flange will be sealed fine if you use a bit of silicone on the sump gasket. 9 out of 10 engines that fail soon after rebuild are because the pump breaks due to incorrect fitting. Ford changed the design in 1986 to try and make it a bit more idiot proof but in my experience there is nothing capable of doing quite as much damage to an engine as a really determined idiot.



Edit. This would sort of make sense as the gears would float and center untill the bolts done up then the gears of the pump are stuffed into the oilpump case . Just thoughts.