This is from a Facebook thread where the advice given by John Fowlie (@big_m) is too good not to save. First, “Dave Fury”'s description of the problem:
So my power steering unit is leaking bad on the bottom. I am not a mechanic and am afraid to take it apart for parts may fall out. Is it just the seal right there? Does anybody know? I could sure use some advice on this.
John’s reply:
That’s called the sector shaft seal. It can be replaced without removing the steering box, but you do need a pitman arm puller. The kit with the new seal includes a new seal, washer, and snap ring, and should still be available at NAPA auto parts, or other full serve parts store. Step 1 is to jack the front end of the car up, and set on stands. Next, remove the large nut retaining the pitman arm. Then, using the puller, remove the pitman arm, which will expose the snap ring retaining the seal. Remove the snap ring with the appropriate pliers, then place a drain pan beneath the steering gear. Fill the power steering reservoir, then turn the steering wheel hard to one side or the other. The extreme pressure will blast the seal, washer, and remaining fluid into the drain pan. Carefully install the new seal, making sure the lip is facing the pressure side, then the washer, and finally, the snap ring. Be sure the snap ring is seated in its groove, by tapping lightly with a screwdriver and small hammer. Reinstall pitman arm and retaining nut, fill reservoir with fresh fluid, and check for leaks. If the unit is still leaking, the snap ring may have not been seated fully, or the sector shaft surface is scored, meaning the steering gear needs an overhaul.