Power assist steering.

[PwrWgnDrvr]

It is not an "adjustment".
I just went and looked at one on the shelf, and the total "end play" is barely 1/4". That is what actuates the control valve. In other words, there is only 1/4" of travel between assist for right turn and assist for left turn. When centered, it goes straight, so actually it only moves 1/8" to actuate the valve and get assist in the turning direction.

[MadMC63]

As a curiosity... The valve is centered automatically by hydraulic pressure and fluid flow is directed back to the return side/reservoir by small holes in the spool valve, right? No hydraulic pressure is directed to the ram, right? If you make a left turn the pitman arm applies physical force to the ball stud applying physical force to the spool valve moving it toward the front of the truck allowing pressure to pass through the valve to the side of the cylinder that forces the ram to extend, right? If you make a right turn the pitman arm moves away from the valve pulling the control valve assembly as a whole, right? Here's the question. Since the spool isn't physically attached to anything at either end and merely rest within a tube and is pressure centered by fluid pressure, pushed one direction by physical force and re-centered by fluid pressure what moves the valve in the opposite direction to make the cylinder retract? You probably think I'm an idiot but I really don't see it.

[PwrWgnDrvr]

As a curiosity... The valve is centered automatically by hydraulic pressure.....Since the spool isn't physically attached to anything at either end and merely rest within a tube and is pressure centered by fluid pressure, pushed one direction by physical force and re-centered by fluid pressure what moves the valve in the opposite direction to make the cylinder retract? .....

No!
There is a bolt on one end of the spool that connects it to the actuating sleeve, which is connected to the pitman arm. That is what moves the spool back and forth. Looking at the exploded view, I see a pin that could have been left out by the rebuilder, or possibly someone unfamiliar with the design may have added shims to stop the movement of the sleeve.
Since everything else has been checked and seems to be functioning or connected correctly, it appears your problem is between the connection of the pitman arm to the sleeve and the spool.

[MadMC63]

Just finished reinstalling the valve body. The pin is definitely there and the pitman arm definitely moves the spool valve back and forth. I remembered a pin but couldn't place it in my mind so I ripped everything apart and verified it. I don't have the turning pressures yet, still waiting on help to show up. All of the parts match up to the exploded view. Nothing missing and no extra parts.

[MadMC63]

I believe the culprit has been identified. All test were performed with the vehicle supported by jack stands. Idle test produced an approximate reading of 100 psi and with the shut off valve in the closed position the pump produced approximately 900 psi. Right turn produced a maximum pressure of approximately 900 psi where as the left turn pressure did not change. Left turn remained the same as the idle test. Bad cylinder @#$%&.

Anyone happen to have a perfectly good, extremely hard to find cylinder ( that they been looking for an excuse to get rid of) lying around?

[PwrWgnDrvr]

What do u think is wrong with the cylinder? It would have to be allowing fluid to flow thru it in order to stay at low pressure. Why would fluid flow thru it in one direction and not the other? Sounds more like a bad control valve.....

[MadMC63]

you're saying there's an issue with the spool valve? That the valve is allowing pressure to pass through it constantly in one position? Looking at the spool valve it appears to be the same on both ends and it fits the bore in either direction. Is the spool valve directional?

[PwrWgnDrvr]

Yes, yes, yes and no.

The only way the pressure stays low is if the fluid continues flowing. Fluid does NOT flow THRU the ram cylinder, ever, unless the seal is bad on the piston, or the cyl is damaged. Since it seals one way, its highly unlikely that it wouldn't seal the other way. U could test the control valve by disconnecting and plugging both lines that go to the cyl. Then when u move the spool valve to left or right the pressure should rise the same each way. If it does, the cyl is bad. If it doesn't, the valve is bad.

[MadMC63]

Guess what I'll be doing sometime tomorrow...

[MadMC63]

With both lines plugged at the valve the results are the same. I cant see the gauge but know right turn produces pressure and left turn does not. Engine rpm changes on right turn but does not change on left on left turn.

[PwrWgnDrvr]

There u go....defective control valve.....take it back to the rebuilder!

[MadMC63]

You probably will believe this. When I said I disassembled the valve and all the parts were there I was wrong!!! I separated the valve and left the shuttle attached to the pitman arm and poked around pushing and pulling. Today I removed the valve assembly and started a complete disassembly and guess what?... NO PIN!! I know it was there the first time because it was there when I took it apart before the second rebuild. Nothing to push against to actuate the valve for a left turn.

[MadMC63]

I just came back from the shop that rebuilt the valve the second time. Cecil and Bubba kept the valve for 5 1/2 months and today, with a toothless smile, gave (out of the kindness of their hearts) me a role pin. I'm pretty sure what was originally there was something along the lines of a solid case hardened steel pin. I'm a little gun shy and my brain say's no way this substitute will work. Any thoughts?

[PwrWgnDrvr]

Shouldn't hurt anything to try it and doesn't handle much force, so go for it

[MadMC63]

The very small spacer on the pitman arm side of the valve had been used as a washer for the retaining nut on the opposite side. Roll pin installed, valve installed, same results. While I had the valve apart I used air pressure to test the spool and body. All air pressure exited through the appropriate holes. The only notable oddity was that in the neutral position air exited through all holes. If right and left were blocked it all exited through the return hole.

[PwrWgnDrvr]

.....The only notable oddity was that in the neutral position air exited through all holes......

Correct, that's why it is "neutral".

Do the same pressure test again, right and left with lines to cyl capped.

[MadMC63]

I went a different route. I thought about the air test and the pressure test and thought the spool valve should be further in the valve body so... I replaced the spacer that's between the spool and the screw with two 1/4" flat washers and tested it, the symptoms reversed. I removed one flat washer retested and now it is working. The original "spacer" was paper thin and the new washer is roughly 1/8" thick. Hindsight can be painful.

[PwrWgnDrvr]

Yup, the spool has to be located (centered between the ports) very precisely in the body. Bottom line to me is the rebuilder did a *#%^@ job. Goes to show that just cuz u paid a shop to rebuild something, doesn't mean its right.

[MadMC63]

The truck really is a beater in ever since of the word but I try to improve it every time I work on it. I really appreciate you guys taking the time to help with this. Really made me think and yes it hurt. I don't know how big you are but I'm thinking , Worth your weight in gold. Thanks a bazillion!!!

Power steering pump and hard lines.

IMG_0496.jpg (33.02 KiB) Viewed 1192 times

Control Valve.

IMG_0498.jpg (27.47 KiB) Viewed 1192 times

[digdoug]