I have a 2003 S-Type 3L with 100K miles. I was driving with a brake pedal one minute, turned on my street, and the pedal went to the floor. I was still able to stop the car in my driveway. Did new rotors and pads 5K miles ago. All was well since then. I checked the reservoir, and it was full, thought the fluid looked dirty. I have had the car for 5 years and have not ever changed the fluid. With the car off, I pumped the pedal and it pumped up stiff. With my foot on the brake, I started the car and the pedal went to the floor. I read through every brake related post. It looks like a fluid change and/or replace the master cylinder. Did I miss another potential cause? I am not a mechanic, but I can hold my own with a how to guide. Is there some gotcha waiting for me in replacing the master cylinder? Thank you in advance for the advice.

 

I think you're on the right path.

 

If you start the car and the pedal sinks to the floor, the master cylinder is bypassing and needs replacement. Just be sure to bench bleed the new one prior to installation.

 

Has anyone used the Dorman #M630264 Master Cylinder?

 

Dorman parts are fine. I've used them for years and have never had a failure.

 

I've used several brands of master cylinders in various vehicles and I have yet to come across a bad one so I would think you would be ok.

 

Thank you all for the reply's. I ordered one from Parts Geek. I'll post back when I'm finished.