E30 braking issue

[Brice325i]

I just started experiencing an abnormality in my 87 325i when I brake. The pedal seems to want to go all the way down to the floor sometimes. Other times it acts like it has for years. I checked the brake fluid reservoir and it is full. No puddles underneath the car either. I did however, find that a black liquid underneath the rear passenger side near that tire seems to have sprayed. It's still wet. HELP!

[roguetoaster]

If it's really not leaking (do check that) then I'd suspect that the master cylinder has given up. However, it is possible that the axle is tossing grease instead of the brake system.

Is the pedal sinking to the floor rapidly or just steadily dropping as you apply constant pressure?

[TobyB]

master cylinder

and/or a leak. Figure out if your mystery fluid's brake fluid...

t

[Brice325i]

Gradually going to the floor

If it's really not leaking (do check that) then I'd suspect that the master cylinder has given up. However, it is possible that the axle is tossing grease instead of the brake system.

Is the pedal sinking to the floor rapidly or just steadily dropping as you apply constant pressure?

[e30onBBSs]

https://answers.yahoo.com/question/index?qid=20060728170127AAhGrZ9

Check everywhere not just MC if you haven't

[101]

If the fluid reservoir is staying full and there's no visible leak at any of the lines or calipers, then I concur - the master cylinder is the likely issue.