Interesting thread. I bought my first 240 this year, and it had a thunka-thunka noise from the rear when the brakes were applied and a rattle when they weren't. The fluid was brownish. It passed the relatively tough UK inspection like this, which I find surprising. There was also a steering vibration over 50mph. The rear pads and rotor appeared to be fairly new, so I changed the caliper and the brake line going to it (had to change the line because I managed to round off the nut at the caliper). The thunka and vibration were still there, but less pronounced. I changed the rear pads and rotors, and both the noise and vibration disappeared. On close inspection the noise appeared to be because some brake pad had melted onto part of the rotor, caused by a partly seized caliper. If I hadn't dealt with it I assume that the brake fluid could have boiled -- it must take a lot of heat to start melting a brake pad. The rattle was bad caliper hardware -- a cheap fix. Now the brakes feel very firm and powerful, but the fluid is still tinged with brown -- so more bleeding necessary. Even partial brake failure can be scary: I had a front line blow on a 1972 Saab 95, and was very lucky not to hit the car in front at a stop light. The failure was due to my installing new front flexi hoses that were much stiffer than the Saab OE line. The nut at the caliper sheared off after a few months of driving.