I started a thread in the F series 80-86 forum concerning this

Just installed a new red head gear and borgeson shaft. We had power steering for about ten minutes on the test drive and then it failed?!

We checked for leaks and after bleeding I had to reverse and maneuver around other cars with lots of 1st and reverse gear until we got out on the road. It performed great then when I got it onto the open road the steering suddenly went heavy after a few minutes. Stopped and checked for leaks and found none. It was still a bit foamy so we took it to a parking lot and gave it ten minutes of hard lock left and right but no change even after the foam dispersed. I drove it for a further 10 miles and checked the fluid(No foam and still no leaks) I'm wondering if debris got into the lines somehow and caused the pump to fail. My friend (who is a mechanical engineer)thinks we may have blown a seal in the new steering box but I am doubtful of that since its a red head who have an outstanding reputation.

One thing we did do was cut through the return line because we had real trouble lining up the connection. We installed a coupler on the line so maybe some swarf got into the pump and damaged it?

I'm shooting in the dark here because we did everything right as far as we know.
Any ideas what could have caused this?

https://www.ford-trucks.com/forums/9...g-failure.html

 

The first thing I'd do is put a psi gage in the high psi line and see where your at.

 

Don't own a PSI gauge but we did loosen the high pressure line and cranked the engine. Fluid did come out under pressure which would suggest that the pump was working. Another thing we noticed though was that the pump does not go into relief (i.e. No pump whining noise like you usually hear when turning on full lock) Does that tell us anything?.

 

What pump are you using, and do you have a cooler or at least a loop of tube exposed on the return side? The Ford pumps are really sensitive about heat. I picked up a plastic bag around the cooler on one of my old trucks, and fried the pump in about 45minutes.
Another thought is that the valve in the gearbox could be stuck, but it usually sticks just a hair to one side or the other giving a bit of a tug on the steering wheel.
What fluid are you running?

 

Problem solved. I changed the pump. Took about 20 minutes to fully bleed the air out. I now have my power steering back. The drive home was great with the new borgeson shaft and red head box. Steering is nice and tight and my wandering issue is gone!