Looking for suggestions on this before it becomes a major problem:
I was driving my '73 F100 in a parking lot today and noticed when the wheel was turned about 1/4 (90 degres from center) I heard a soft hissing noise. It occurred in either direction of wheel travel. The more I turned the wheel the worse it got until near full lock, then it stops. If I turn the wheel, shift into Neutral, then rev the engine a bit, I hear the hissing/gurrgling get louder and can feel the steering wheel pull a bit. So far normal steering has not been effect and the truck it still driving fine.

I don't know if it has always done this and I never noticed or if this is new. I replaced the Power Steering pump (NAPA) and power steering hose (Advance) back in November. I checked and there was a decent amount of fluid in the resevoir. Thoughts on this? My fear is that something has started to wear out with the hydraulic cylinder...what symptoms does that usually give?

 

Next time it does this agiain check to see if fluid is foamy at all. Air bubbles are bad and will ruin your pump and make steering bad

 

Will do. But what would allow air to enter? I'd guess a leak at one of the compression fittings (either pump to return hose, pump to pressure hose, pressure hose to cylinder)?

 

Did you use the same type fluid when you filled it with new pump. What do you run type F ATF? Or p/s fluid?
Might want to bleed system with the wheels in the air cycling it lock to lock..

 

I filled the p/s pump with Valvoline power steering fluid and it had been working fine. I though bleeding the system was just turning the wheels back and forth to full lock?

 

Yeah I think you need to either disconnect drag link or raise tires off the ground.