P/S pump problems

[easyrider]

I've got problems!! Swapped in my 5.9 mag from a Dodge Dakota into my 65 Dart. The p/s pump is foaming the fluid and making a lot of noise. I swapped in another pump, same thing. I installed a kit in the original pump that came on the 5.9, same thing. When I first crank it, it is fine. It steers just like a Mopar, no effort required. After it starts to foam, steering is no so good.
Does the pump from the Dakota make more pressure than the Saginaw pump I had installed on the Dart? I tried to use the pump that I had on the 273, but the body was indexed differently.
I need help before I start throwing money at this problem.
Tom

 

[barty005]

Sounds like it use as air in it run it let it settle top up and repeat. Check for leaking lines or right rack maybe allowing air in as well.