I was driving back from work and when I hit the brakes to stop at a stop sign, they were very soft and the pedal sank to the floor - felt like the master cylinder went out.

I pulled into a gas station, stopped the car and waited for a few minutes. Then I started the car and pumped the brakes and after a few times, the brakes were back to normal.

What could be happening? The brake fluid is need of a flush - it is black in color. I recently checked the brake pads and they all are good. I checked to see if there is brake fluid leaking anywere and there was none.

If I just bleed the system, would I be ok or do I need to go in for a new master cylinder?

Thank you for your responses.

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1986 300E (3/2002) Rear ended and totaled (10/2009)
2000 Xterra (5/2000)
1992 400E (11/2009) -Sold
1986 300E (12/2009) - Sold
2004 E500 Wagon (6/2013) - Sold