E60 530 petrol 2004, loss of brake fluid problem :(

[oneeyefrail]

Hi all I wonder if someone can shed some light on this for me ,
A week ago my low brake fluid light came on so I figured it was just pad wear so topped it up. Yesterday jumped in the car and the lights back on ( don't use it a lot) and the brake feels stiff and the pedal seems to travel more but they still work ?, no sign of leaks inside or out, question is is this a common fault ? Could it be the master cylinder seal gone and pulling the brake fluid into the servo ? Any thoughts or people had similar symptoms ?

[brettski]

Welcome to the Werkz

Is there a puff of smoke at all on startup to indicate a failed MC seal?
When the engine is off, put your foot on the brake pedal and notice if the pedal softens when you start the engine.

[oneeyefrail]

Not sure about smoke to be honest but the servo seems fine as it falls away when I start the engine , can't see any leaks so could only think its passing into the servo from the rear of the mc ,was thinking about pulling the mc off and having a look in behind , anything I need to watch for when doing this ?, the abs seems to kick in more easier too but this could be due to the weather

[Jack Dabsy]

Did the fluid run really low? If yes, it could be a small air-lock in the rear lines !!

[oneeyefrail]

Hi, just back form offshore with work and theres no smoke when you start it, no it didnt go that low cause as soon as the light came on i topped it up ,both chambers in the resovoir where at the same level so i assume its not leaking from a braking system...also forgot to mention that this has the active steering too.. I just took the MC out in the hope there would evidence of a leak from behind but nothing ... its just vanishing lol...

[Jack Dabsy]

Has to be going somewhere because it is VHT fluid !!