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It’s common for the power piston in the gear box to wear into the box on one side (the side against the frame) and that can cause hard steering to the left, I’ve had to junk a few boxes because of this wear.

Did you open them up? Just wondering if there is a way to tell definitively w/o pulling the box from the truck.

To see the wear on the housing they have to be opened up, I’ve never heard of one seizing up that been in use, I did have one that someone gave to me that was open to the elements and completely frozen from rust .

Basicly what happens over time is the end of the piston will wear the housing down and allow the piston to **** slightly and then it requires way more force to overcome the piston dragging on the housing. The very first box I redid was when I found out about the wear problem, didn’t even know to look for it until after I had rebuilt the box and it had very low assist to the left and poor return to center from the left, figuring I screwed up somewhere I pulled the box out and apart and that’s when I saw excessive wear on the housing, it felt like a wash board it was that bad.

But before condemning your box I would make sure none of steering linkage/ ball joint or even axle u-joints are binding first, even changing the fluid in the power steering system wouldn’t hurt to try, worse case you’d be out a couple bottles of atf to flush the system.

These steering boxes have several wear areas besides the sector shaft adjustment on the top of the box, spool valve wears or gets crud in it, the recirculating ball assembly that couples the input shaft to power piston can wear the races and ***** giving a loose input shaft but tight box other wise, sector shaft wear/ mesh load out of adjustment, wear of the cylinder/case where the power piston travels to just name a few I know of off hand.


As for flushing the system I usually just pull the return line off the pump and drain the pump that way, then I have a bunch of vacuum caps kicking around and stick one on the pump, I then put the front end on jack stands and cycle the steering back and forth until as much of the old fluid is pushed out of the gear box, then I fill the pump and start the engine and cycle the steering while adding fluid to flush the box out after that just put the return line back on, top it up and with it running cycle the steering from stop to stop to bleed the air and add fluid if needed. Mite be over kill but works for me.

Leave the high pressure line alone unless you want to replace it, it doesn’t need to be removed to flush the system.

As for the steering linkage check, it’s free and easy to do before condemning the gear box. One time I put adjustable camber/caster shims in and set it to full caster, couldn’t turn the tires more then half way and the upper ball joint was binding up everything, turned great the other direction that I didn’t change yet, I don’t think this could be your problem but it is one way the steering can bind.