Hey all, posted recently about how my brake pedal would fall to the floor randomly a few times over a few months. Also, twice it was hard to actually brake. Everyone seems to think it's the master cylinder, which I suspect it is as well. Anyways, there is another development I wanted to ask about before delving into this problem.

I hear a whining noise coming from the rear driver side wheel well. It's not there when the car is sitting ever, regardless of RPM. It starts once the car gets going and it starts pretty quick (even under 10mph). It is not consistent sounding, the pitch changes, sometimes you can't hear it at all, but it's there on and off always.

What does this sound like to everyone? Brakes? Could this in anyway explain for the pedal falling to the floor or is that independent of this? When I brake, I hear a different sound that is kind of like grinding by the way. Thanks,

David

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1985 300D. 179,000 miles.