Loss of power steering when warm

[mac3687]

Hey guys, I'm throwing in the towel and turning to your collective genius. I've got a 1969 F100 with a 302 that had been leaking power steering fluid for a while. I finally replaced the pump and high pressure hose, as well as the section of bulk line that made up the return section. Looking back, I don't think I properly bled it - I filled it with fluid, started it, stopped the engine after 10 second or so, added more fluid until I hit the line, and called it a day. Another mistake I think I made was I used generic Prestone P/S fluid, I'm now starting to think I need ATF instead. When cold, the steering is great and it's very smooth/quiet. Once the engine is warm, after roughly 20 minutes of driving, the wheel is tough to turn at lower speeds and there is a noticeable groan when turning. As soon as the engine cools off, the power steering works fine again and the noise is gone. I'm wondering if I need to A.) get all of the P/S fluid out and replace it with ATF or B.) tighten the belt a little bit in hopes that maybe it just stretches when warm and is slipping a little bit. Thoughts?

[Ren]

Twenty years ago, a co-worker of mine added the wrong fluid to a power steering pump in a shop van. It took a couple hundred miles, but the results were disastrous. He got his ass chewed. I wallowed and giggled in the intense pleasure of listening to the chorus and drama of that very long, loud reprimand He was a drunk And enjoyed telling loud tales of his bedroom acrobatics with very ugly women. Especially during lunch. And always scheming a way to get me fired. He didn't like me at all. Not one bit.

But you seem nice. And I think you should waste no time in correcting your error.

[hazelnut]

Did you ever jack up the front tires off the ground and start the truck and turn the wheels lock to lock 3-4 times to burp out any air that's in the system ?