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Saginaw Power steering; P/S fluid or ATF?

Calan

Registered
Hello to all;
Best to use power steering fluid or ATF in my older Saginaw power steering system?

I rebuilt my old P/S gearbox after being encouraged / inspired by folks on this board, and have been very happy with the results. I used power steering fluid, despite the fact that the cap on the pump says, "Use Automatic Transmission Fluid, Type A".

The only issue I have is that when it gets warm, the steering binds. Very little binding, almost imperceptible. When the wheel is at about the 10 o'clock position, on the return, only.

It doesn't do this at any other position, and only when warm, (engine temp +/- 195).

I've backed off the sector shaft, 1/8 turn. There may have been a slight improvement, or I may have just been wishing. I'll back it off one more notch, and see if that helps, but want to make sure I'm using the best fluid.

Not sure how old it is; wouldn't be surprised if it was from the early 70's.
Numbers on the barrel of the gearbox are 5691676. Below are smaller numbers, a 41 and what looks like a 225. Edit; numbers research shows it to be common, used widely, early 70's.

Online research results are not consistent, and there are arguments for both.
All opinions welcome; specific brands appreciated.
Many thanks!
Alan
Central CA
 

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Power

Registered
Assuming you did not change ball sizes, There are 2 critical adjustments I am aware of.
Steering shaft bearing preload and sector shaft. They should be adjusted per manual. When properly adjusted, there will not be any binding, which can only be detected with the unit off the vehicle, using an inch pound torque wrench per the manual. If you feel a bind at the steering wheel, with all that leverage, then there is a problem.

People who are somewhat mechanically knowledgeable would shortcut adjustment by adjusting sector shaft on the car. I have seen alignment techs do that. End result often is scoring of worm shaft, balls and nut, requiring replacement of those parts.

In the past, I rebuilt several of those units from GM cars & trucks. I have used GM PS fluid, which is clear (and expensive) and ATF, which is much cheaper. I have had good results with both. I suspect PS fluid does not have detergents ATF has, but seems to have more anti foam additives.
 

Calan

Registered
Thanks Power;
I didn't change ball size, and adjusted it pretty carefully on the bench before installation.
I'd rather not take it out again if I don't have to.

Any way to check sector shaft adjustment while still mounted?
Can I back it off 'till I feel the slight clunk of play, and then tighten it slightly?
Does the fact that it will only misbehave when hot mean anything?

And, I'm not sure, "bind" is the right term. There's a slight, brief resistance to returning, from the 10:00, when warm / hot. Normal people probably wouldn't even notice.

All suggestions appreciated.
Alan
 

Power

Registered
Re adjustment- I am sending you a PM.
Whenever I rebuilt the gear, I would clean out the pump, and add a magnet if one was not there. Later units had a quarter size disc magnet stuck to the inside of the pump case. Early ones did not. When there was an issue with a unit, I would check magnet. If it had a lot of metal debris on and around it, I would suggest a rebuild. If pump did not have a magnet, I would run it for a while, and drain fluid from pump reservoir into a glass jar. If I saw a lot of debris, and it stuck to a magnet swished in oil, then I would suggest a rebuild.
 

Calan

Registered
Magnet's a great idea!
I should probably rebuild the pump anyway; hasn't been done in a while, I'd guess.
Very much appreciated.
 

Calan

Registered
The answers seem to be;

1. Dexron III automatic transmission fluid. The general opinion online, and from all the wise, "old guys" I could find, is that the older Saginaws prefer ATF. I think this is a '71.

2. Pump was getting tired. I didn't know wear could cause intermittent hesitation while doing slow turns; turns out this has happened to others.

So, with a new pump, and correct fluid, the steering is really smooth, with no clunks, wandering, hesitation, or play. Replaced the lines while I was at it.

"Funny", seems I've been putting the wrong fluid in my wife's 1999 Sienna. I thought because the cap says, "Power Steering Fluid" that ya top it off w/ PSF. But no; read the fine print today, and it says, "Dexron ATF". I learned something today. Flushed and filled that this A.M.

Thanks to all;
Alan
 

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Power

Registered
"Funny", seems I've been putting the wrong fluid in my wife's 1999 Sienna. I thought because the cap says, "Power Steering Fluid" that ya top it off w/ PSF. But no; read the fine print today, and it says, "Dexron ATF". I learned something today. Flushed and filled that this A.M.

Thanks to all;
Alan
Yeah, that is why I kept talking about pump. Usually, when it is badly worn, you feel pulsing at wheel or have to rev engine when parking.

Very much doubt you did any harm. Now if it was motor oil you were putting in, that would be a different story.
 
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