240 soft brakes - please help!

[AlexO]

Originally Posted by Clifford Pope

Should it push at all when not in use? Commonsense suggests to me that if your foot is off the pedal then the MC should not be being activated at all?
And if the MC is being activated slightly all the time than pads will be rubbing slightly, getting hot, causing noise, vaporising fluid, causing vapour bubbles - generally all the faults you are describing.

Second Clifford on this. Rising brake fluid (which is utterly bizarre by the way) would suggest that you're heat soaking the fluid. If the brakes are also binding all by themselves then this would support this theory. I haven't been following the full thread but if you've replaced the calipers I'd recommend checking that all the piston covers are attached properly since any small rock or bit of grit getting stuck in them will stop a piston returning and give you lots of heat and binding (that's from personal experience). This will also be evidenced by one especially hot corner after a long drive.

I'm not sure how rising fluid can suggest an air leak since any air leak in to the system must surely become a fluid leak out of the system once you pressurise it, right? If you're not getting a mushy peddle or losing fluid then it doesn't sound like a leak of any kind.

I'm by no means an expert on this but having had brake problems in the past I feel your pain. If you've replaced all the component except X, Y and Z then that might be the next place to look. I know the last time I looked at that rear bias valve on my 240 I had to wince; grotty doesn't even come close.

Hope that helps,

Alex