I'm a newbie at this stuff and am not overly familiar with the language. '97 SC400. When the car is running the p/s reservoir bubbles over as though it were boiling. I've replaced the air control valve but no changes. My "backyard" mechanic suggests that it "might" be the rack & pinion which I'm willing to purchase if there is some support from this site for that kind of expenditure. Any thoughts are welcome.
ThreePutt2

 

Im new to the sc world too, with my 300, but from my experience the drive train is far more durable than everything else

 

Air leaking in?

Check the Power steering pump lines, and also check the Rack hard lines.

 

has the power steering system been opened at all recently? there could be air in the system. Follow the procedures to properly bleed your p/s system, see if that provides any results. If you're still experiencing the same issue, you might have a bad rack. That isn't all that uncommon with these cars, especially higher mileage ones. Also, with the engine running, turn your steering wheel to full lock, do you hear the pump whine a bit? If not, you could also have a bad pump.