3-second answer: Whine = air in the fluid (low level or a leak) — check level first, then the pump suction hose. Leak on the pump = the o-ring between the reservoir and pump body (~$5). Sloppy steering = the Saginaw box's adjustable lash screw or worn tie rods. Fluid: Mercon ATF (do NOT use power steering fluid).
In order of likelihood
- Low fluid / air — whine at idle and lock. Top off with Mercon, bleed by turning lock-to-lock with the engine idling.
- Pump reservoir o-ring — the classic drip source, right where the reservoir meets the pump. Cheap, 20 minutes.
- Pressure hose leak — the high-pressure line at the pump fitting. Use a flare wrench; don't strip it.
- Sloppy box — adjust the lash screw on top of the Saginaw box: loosen the lock nut, turn the screw in 1/8-turn increments, test for bind. Too far = tight spot (return it!). Real fix for a worn box is a rebuild or a reman (~$200).
- PSOM/PSP sensor — a leaking pressure switch on the pump trips a code and can set the 52 code.
Fluid
- Mercon ATF — that's what these systems take (not "power steering fluid"). Capacity ~2.5 qt.
- NEVER use stop-leak as anything but a temporary patch — it's not a fix.
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