Brake master cylinder?

[tmaoahthfte]

Hi all, changed the brake fluid in my w210 recently, the fluid that came out of the front nipples was dirty, the rears came out clear. Would this be a sign that the seals are starting to go in the master cylinder? The pedal feel was slightly spongy before, feels quite a bit better now.

 

[johnsco]

It doesn't really tell you anything about your master cylinder seals.
The fluid in the calipers doesn't move much and does tend to come out a bit dirty.
When changing fluid, you pump out any dirty fluid from the caliper, so the first fluid that comes out through the nipple often looks like this.