We just got a 72 D100 it's been parked for twenty years. Got it running pretty quick. The power steering was very noisy so I drained it and refilled it with Lucas stop leak fluid. When I restarted it I turned it lock to lock. It was still noisy and not working very well. When I shut it off fluid came out around the fill cap. It wasn't over full it was foamy. I pulled both hoses thinking there was a restriction
There wasn't. Anyone have any idea what I've got gone on.

 

The foaming is air in the system.... Start the truck and turn the steering wheel all the way to the right and then shut the motor off and let it sit overnight.... Then Start the truck and turn the wheel lock to lock and turn it back to the right and shut off the engine and let it sit again... That should take care of purging the air out of the system....
Then see how the steering feels.... Re check for air in the system, should not be any at this point...
Report Back.... Good Luck.... Cheers

 

I will try that. I have to get a new pressure hose it started leaking at the steering box. The steel was getting a little thin.

 

 

I did what you said about 4 times now still pushing fluid out when you shut it off and it steers really hard. I think I'm going to drain the Lucas and put power steering fluid in. The Lucas seems really thick. Thoughts?

 

That would be a good idea...

 

That didn't help either. I'm hoping when I drive it will bleed it out and start working. Its still pushing air out every time you shut it down.

 

Your not filling it too full are you? Level should be down about 4" from the top..... And you re-performed the lock to lock steering bleeding... and it still has white foam when you shut it off?
That indicates to be a Faulty Pump or you have a restriction in the system at some point... Possibly something stuck in the steering gear at this point...
Also one other thing to try... Use just ATF and see if that helps..

 

The funny thing is when I first started it after twenty years it was noisy. Now after draining it and new fluid it hardly makes a sound. But steers like a muscle car

 

I don't think it's the pump because when the pressure hose was bad it threw fluid half way across my garage. I'll probably pull the box off and go thru it. I think there's a restriction somewhere.

 

The proportion valve is held in by 2 screws on the top of the steering box. Those can get plugged up. If you take it off which you should do, mark where it sits on the steering box with a scribe. If you slide that valve up and down, you'll see the steering wheel turn either way. It places more pressure to the left or right. We would adjust those on the road after alignment to compensate for wheel pull and drift.

 

That's interesting, I've never heard that. I'll check it out when I get time. Thanks

 

Well I have a Saginaw box so I don't think it has a proportioning valve . So anyhow I took the box off and pulled it apart and put all new seals in it. It still isn't perfect but it seems to get a little better everyday.