High pressure oil pump problem
 

I have a 2006 ford f350 6 liter. It was having a crank no start when it was hot and cold. Eventually the truck would start. So I took the truck to get looked at and it has a hpo leak. After taking the truck apart I was told it needed some new o rings on the high pressure oil rail on 2 three inch long plugs. The truck was put back together and still had a leak. After taking it apart again they said I need a new branch tube kit. I bought that and had it replaced. Then before they put the truck back together they did another pressure test and said it was leaking from the hpop. So I bought a rebuilt pump from ford and had it installed before putting the truck back together they did another pressure test and said the rebuilt pump was bad. Both my pump and the rebuilt pump leak air out of the same spot. It is a small hole near the gear on the pump. My question is do I actually have a bad pump and a bad rebuilt pump or is the pump suppose to leak from thiS area. I don't know much about it but all of the pump is under an aluminum cover. Can anyone help me?

I also have an 2006 6.0. I had simular issue with the starting. My mechanic ( top ford trained person) pressure tested with air. told me all that it could be but told me very few times is it the oil pump.... anyway the problem got worse where i was stuck for several hours till it cooled. long and short of it, it turned out to be a cracked o ring under the left side valve cover.