Prior to my recent brake job & fluid flush/bleeding, I was having issues with the brake pedal intermittently sinking to the floor when stopped or slowing in traffic. Figured the system needed to be bled and all would be well.

Well...everything seemed fine until the last couple weeks. I am now experiencing a rock hard brake pedal. I sometimes have about 1-inch of travel until it feels as if I hit the firewall. This happens intermittently when hot but ALWAYS happens when the car is cold. When this happens before the car is warmed up the car doesn't want to stop for shit...which is obviously somewhat of a concern. I still get the random soft pedal issue as before, but it is not as pronounced.

It gets better...Last Wednesday in Orlando I started up the car to drive to lunch. Get out of the car and notice some small drips of an odd liquid on my shoe. Sure enough the liquid it is the consistency, odor, and color of brake fluid. It did this again later that day but I haven't seen any leaking fluid inside the car since. So either the brake fluid is leaking from my brake booster, or perhaps my clutch master cylinder which shares the brake fluid resivour.


So now what? I know there is no air in the system. New pads. New rotors. The only thing left is the master cylinder and booster, right? I'm taking the car into Ernie Haire this Friday for diagnosis. My only fear is these issues aren't consistent. Granted the pedal feels like shit 95% of the time, but the real scary shit is pretty random. Is there anything anyone here can tell me about testing brake systems that would make me a bit more educated when I talk to my service advisor on Friday? The help is greatly appreciated.

 

Sure sounds like a master cylinder. Air in the system would feel spongy all the time.
If the booster were bad you would loose "power" but not pedal. hope this helps

 

how low did you let the resevour get?if you got air into the abs system, i do not think you can get the air out unless you have a special tool. (expensive tool)

 

well one way to check is with the car off try and push the pedal to the floor, if it leaks down slowly, your master is bad. if it is firm turn the engine on and press the brake on and off, listen for a hissing noise, if you hear a hiss the booster is shot. if not and your master and booster pass the test, with the engine running, push the brakes like youre stopping, if the pedal goes to the floor, you have air in your system

what sequence did you use when you bled the brakes?

hope that helps some

 

I know it is a sealed system, but the fluid was dirty as hell and it desperately needed a flush. I used a pressure feed bleed system to flush/bleed the brakes starting with the caliper furthest from the master cylinder (right rear, left rear, right front, then left front). Used 10psi on the pressure bleeder, which is under the recommended pressure according to a ford tech. Resivour isn't overfilled....so everything is as it should be in regards to fluid level, condition, etc.

I put a thread over on Focaljet and have done some searching on this subject. It almost seems as though this is fairly common. Quite a few have had failing master cylinders, particularly with the brake fluid leaking into the interior. Oddly enough, I never had this sort of issue after 60k hard miles on my old '00 ZX3. Perhaps some were flawed from the factory? I'm just hoping I don't run into this issue again when the warranty has expired.

 

my catera did same thing, was the master cylinder, my explorer also did it.