I have over 220k miles in my 92 400E. These power steering pumps love to leak. The shaft on mine recently got so bad that I had to replace the whole pump because it wouldn't seal.

Regarding the noise. If you have an inch of slop in the steering there is something worth checking out there, but there is something about the 92 front brakes that they changed in 93 to fix a low speed groaning noise when turning. I'm used to the noise now.

Try this test to see if it is by chance the brake calipers chattering. Place a slight pressure on the brake pedal next time you hear the noise and see if it goes away immediately. If it does, I would lean much more to the chattering calipers being the source of the sound.

I understand the 93 400E has a thicker rotor and a different caliper that solves the problem. Me? the occasional noise doesn't bother me now that I know what it is.

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02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)