My '86 420SEL has dragging front brakes that make a high pitched squeal over 30mph. It started really soft, but the last few weeks it has gotten downright annoying when the windows are down. I have checked the brakes and everything looks okay, and the brakes work really wonderfully, although when jacked up the front wheels do not spin freely. I don't know what the problem is. Also, if I put my foot on the brake pedal the slightest bit, the sound stops instantly. Once released it is back in two seconds. Any help would be appreciated greatly, as I am somewhat embarrassed to make these sounds while driving around.

Thank you.

Nick

Possibilities:

The rotors are slightly warped? I had a similar sound that was ultimately diagnaosed as warped rotors. Once the rotors were turned the noise ceased. Do you feel a pulsation in the brake pedal when braking?

The pads are near the end of their life? Check the thickness of the pads.

The calipers are hanging? Sometimes caliper pistons will not decompress which causes undue pressure of the pad on the rotor during normal driving. In this case the calipers still work fine to stop the car, but don't release fully.

Others?

I had a similar problem with my volvo. I had over filled the Master cylinder... drained it down below the "max" line and no more squeal. Worth a check.
Intruder

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Are you using OEM or Mercedes brake pads? I've had bad experience with those off-brand "lifetime warranty" brake pads... symptoms somewhat similar to what you're describing. After a few months of driving around with those things on the car, I just couldn't take it any more. Off with the lifetime-warranty pads, on with MB pads from the dealer - problem solved.

- Nathan
83 240D, 250k miles