Power steering trouble shooting

[fireguyfire]

I am about to trouble shoot my power steering system and was looking for some tips to isolate my problem.
I have a new power steering pump, new hoses and a new (rebuilt) gearbox. The only original part of my system is the valve body which I moved from the old gearbox which was super sloppy, and my old pump was pooched.
Anyway, I hooked everything up, filled and purged the air out of the system, and started the car. Everything seemed ok but when I took the car for a very short drive to check the power assist, I could tell right away I had none and when I lifted the hood after putting my 68 back in the garage, the pump had built pressure, but was obviously dead heading as it backed up fluid and puked it all over my newly restored engine bay via the cap.
After a bunch of cleaning, I am now ready to find out what is wrong but I want to systematically test the system to find the flaw. The pump obviously built pressure, and with the pressure hose disconnected (and the car off of course) if I spin the pump pulley by hand I get flow so Im sure its good. I guess I could pull off the new hose lines and snake them to make sure there is no plugs there; highly unlikely but you never know?
Again the obvious culprit to me is the valve body so I pulled it off tonight and went through it via the shop manual. I did find that the spool valve was very sticky but once I took everything apart and cleaned it and lubed it both valves in the valve body are operating perfectly now.
How can I test that my gearbox is good even though it is new? With the valve body off I'm guessing that I should see the pivot pin on top move forward and backward as you turn the wheel, which would move the spool valve back and forth in the valve body? I haven't checked that yet.
I should also mention that the valve body was on the gearbox correctly, and the valve spool hole was over the pivot pin.
Anyone have any other suggestions on what to check or how to trouble shoot that everything is working right before I put the valve body back on, and fill the system? Im a little gun shy on another power steering fluid volcano under my hood!

[BLK 68 R/T]

Who rebuilt the box? Is it just a reman from the local parts house?

[fireguyfire]

Year one gearbox

[fireguyfire]

Didn't have much luck trouble shooting this stupid system today but I will keep at it.
Makes me wonder if I wouldn't be better buying a full new matched replacement system, or go the rack and pinion route.
Anybody gone either of these ways? I see the unisteer rack and pinion kit gets mixed reviews.
Opinions?

[BLK 68 R/T]

Just guessing here but I think the pump itself might be the culprit? They have pressure valves inside as well. I wouldn't think anything would be wrong with the box itself, but again just my opinion. I would try another pump before doing anything else.

[fireguyfire]

Played with the PS system today; pulled the low pressure hose off of the pump and put it into a jar; pulled the coil wire and turned the car over for a good minute or 2; no fluid in the jar. If I turn the gearbox i get fluid in the jar so I know I had fluid to the gearbox when I had the problem.
Pulled the high pressure hose off and snaked it and blew it out; no blockages. Had my son turn the car over while I held the disconnected end (from the gearbox) into a jar; again no fluid movement.
I guess when I had my pressure build up it must have pooched my pump as it will not flow fluid.
I did notice the PS fluid in the reservoir was frothy with air bubbles after we were done so I'm not sure what that means.
I am assuming turning the car over with just the starter should spin the PS pump fast enough to move fluid through disconnected lines?

[charger Downunder]

Here from another site make sure you pay attention to the last part about boiling the fluid.


        Tip from Brad on How To Adjust Your Steering Box:

        If you were to look at the top of the steering box, you'll see a screw surrounded by a large nut. The screw is about 3/8 of an inch in diameter, and will have either a slot (for a standard, straight-bladed screwdriver) or a hex (for an Allen-type driver) in it's top. The nut is a 3/4- or 11/16-inch nut that locks the screw. Holding the screw with the needed driver, loosen the large nut. This will free up the screw. Turn the screw in (tighten) about a 1/4 of a turn. Snug up the locknut, again while holding the screw to keep it from turning, start the car, and see how loose the steering is. The wheel shouldn't move more than about an inch before you see even the slightest movement at the front wheels. I you need to, repeat the process until you get the desired amount of play at the steering wheel.

        A little adjustment goes a long way. Be VERY careful not to turn the screw in too far. Too tight will make your car REALLY notchy on the road, and overburden the pump, boiling the power steering fluid. And you MUST check the play with the engine running. Looseness when the engine off is normal.

[68 RT]

"Anyway, I hooked everything up, filled and purged the air out of the system, and started the car". How did you do that with out starting the car? Sounds like you have air in the system. If you did not start the car to bleed it that is your problem. 

[fireguyfire]

Just though I would add an update; changed out the faulty TRW pump and put in a federal. I now have beautiful power steering!
I'm guessing the pressure relief valve on the rebuilt TRW wasn't working which is why it over pressured and blew.
Talked to a guy who has been rebuilding Mopar power steering pumps for 40 years and he said the vane design on the TRW is terrible, and he recommended the federal which is working awesome.

[Kern Dog]

Opinions vary, but there is a reason that the Federal pump was discontinued. The Saginaw pump was a better design.

[c00nhunterjoe]

Opinions vary, but there is a reason that the Federal pump was discontinued. The Saginaw pump was a better design.

I agree. Saginaw is a better pump, costs 10 bucks to rebuild. Still in use on vehicles manufacturered today.

[fireguyfire]

This guy said the same thing, that the Saginaw was the best design of the three followed by the Federal and then a far distant third is the TRW. I wanted to keep as stock of look as possible so the Federal was the call and I am thrilled with it. I guess we will see if it holds up over time!