This is my first post here! I got a 1991 300te for my fiancee last year, and the first 6 months were a joy, but now an unbearable squealing noise has developed.
Here are some notes on this:
I flushed out the power steering system and put in the wrong kind of fluid at first ( for a few hundred miles), but then thoroughly flushed the system again and changed the filter and put in febi fluid, and the performance of the steering is great now.
I looked at the strut and noticed that the rubber bellows is shot, and the rubber top mount also is cracked. BTW, car has 170k on it. You can reproduce the squealing noise by pushing down on the front of the car ... although when driving the car, it appears that you can ALSO cause the steering noise by turning the wheel with out any up/down movement.
I was about to buy struts, but talking with phil, he suggested its probably control arm bushings. This is kind of bad news to me cause the control arm bushing job is dangerous for a diy, no?
Oh, one other thing related to diy, etc... this squealing noise developed about 30 miles after I had the car in a shop for safety inspection. Perhaps the pro jacked the car wrong causing damage? sabotage has also run through my mind.