PS pump went out on my '71 F-100. No problems with the replacement pump, but now the PS gearbox leaks from the upper shaft attached the the steering column. How much trouble is the seal trplacements on the gearbox? Don't think I need a rebuild because there is very little play in the box. Just wondering about the ease or difficulty of replacing the seals.

Thanks,
Noah W.

 

I just did a total rebuild on my '68 F-350 steering gearbox (at 400,000+ miles) and it was not horribly difficult to do the whole thing if you are comfortable with hydraulic systems. This was with the steering gearbox on the bench. I just took a look and doing just a seal while the box is bolted to the frame looks tough, even if you got the master cylinder (& brake booster, if you have one) out of the way. In any event, you have the problem extracting the seal, which will have the steering shaft still filling it. There are tools & techniques for doing this, but it is not likely to be easy. Because I had the whole unit apart, I could remove the shaft and then drive the seal out from the "inside" direction. I could also press the seal into place without having to deal with the shaft. With all this in mind, I should give you a firm answer that replacing the seal with minimum dissassembly would be difficult.

For general interest, soft parts kits for these come in two versions. Mine was leaking out the bottom (pitman arm shaft seal), but I wanted to do the whole job. My NAPA kit seemed to be very complete, including directions. I followed the directions which said to remove all the soft parts. I then found that the main piston seals (which I had by now, cut off, to minimize scratching anything) were NOT INCLUDED.

I got on the net and found a very cooperative guy in a small steering shop (in MO, I think). He explained that not everyone bothered to replace the piston seals as they usually are OK and are a bear to get off & on. (They are a teflon-filled material that does not stretch much without breaking.) I already had a kit, but I offered to buy another whole kit because I knew he was already giving me more time than the profit he would make from me. In turn he offered to give me an extra set of these rings in case some broke while I was "practicing". (Cheaper than NAPA, as well.)

What did I learn?

A. Do not remove the piston seals unless they are obviously bad.
B. If you do have bad piston seals, be sure to get a kit that includes them.
C. When installing the seals, soak them in boiling water for a few minutes to soften them. Even then, they are tough.
D. After they are in place they will be stretched; place the whole piston & seal assembly in hot water to soften the seals and then place the piston w/seals in its place in the main housing bore and let the rings cool down in place. They will return to close to where they started.

I did not break any piston seals, so now I have a complete kit for the next job. The gear works fine and does not leak.

Final thought: make sure a pinhole leak is not spraying fluid. The best way to check is to wipe everything clean & dry as much as you can and then with good light and the engine running have a helper turn the steering wheel back and forth while you watch. Before I did the steering gearbox rebuild I had a hose that looked fine and was not oily. Everything else was oily because there was a very fine stream that shot out of the hose, but only under pressure.