93 Taurus Brake Problems

[wvkeith]

I had no problems with the brakes then one day I applied the brakes and the pedal went to the floor. After pumping a couple times they worked fine. A couple days later the same thing happened. I replaced the master cylinder, rotors and pads. The brake pedal now now seems spongy and goes almost to the floor. There are no leaks anywhere and I bench bled the master cylinder and bled all 4 calipers. The car has 4 wheel disc ABS.

[KimMG]

Sounds like a bad master cylinder.

[shorod]

Originally Posted by wvkeith

I had no problems with the brakes then one day I applied the brakes and the pedal went to the floor. After pumping a couple times they worked fine. A couple days later the same thing happened. I replaced the master cylinder, rotors and pads. The brake pedal now now seems spongy and goes almost to the floor. There are no leaks anywhere and I bench bled the master cylinder and bled all 4 calipers. The car has 4 wheel disc ABS.

Does the pedal ever feel firm, or is it spongy from the moment you start to press? If it start firm and loses firmness, then I'd suspect a bad replacment master cylinder or bench bleed. If the pedal is spongy all the time, I'd suspect you did not get the air out of the lines. I'd suggest bleeding the brakes again in the recommended sequence being certain to not let the master cylinder reservoir run dry.

Or, pick up a set of Speed Bleeders and replace your bleeder screws. These are well worth the $16 for a set of four and most local parts shops stock them (at least around here - Iowa). Speed Bleeders incorporate a 1-way valve on them. You simply open one a quarter to half a turn, put a hose on it to guide the fluid to a bottle, and slowly pump the brake pedal. The spring loaded bearing will allow fluid to escape under pressure, but when pressure is removed, the spring pushing the ball bearing against the seat and closes the valve so you don't suck air back in to the line. After about five presses of the brake pedal, close the bleeder screw and move to the next caliper. When the Speed Bleeder is closed, they function just like a normal bleeder screw. I think if every DIY'er had Speed Bleeders on their cars, they'd all flush/bleed their brakes annually as recommended! Nope, I have no ties to Speed Bleeder, but I use them an all our cars. They are especially handy on my track car where I change pads at the track and keep the fluid in the system fresh to prevent brake fade.

-Rod

[wvkeith]

Originally Posted by KimMG

Sounds like a bad master cylinder.

I suspected a bad MS too at first so I got another and put on and it's the same. The pedal does not start out firm. When I first push it, it's spongy and goes to the floor. But after I pump it, it firms up. I did notice that when I removed the lines from the original master cylinder, there was enough pressure to make brake fluid spray from the lines, but now if I remove the lines from the MS, it just drips. I wonder if the ABS hydraulic unit is faulty or has air trapped inside?

[Jeckler]

It's possible there is air in the ABS unit. There's two ways to go about getting the air out. The 'factory' way is to take it to a shop where they can cycle the ABS unit with the car on the lift. The poor man's way is to get it up to speed and romp on the brakes to engage the ABS (if you can get enough pressure).

[wvkeith]

Originally Posted by Jeckler

It's possible there is air in the ABS unit. There's two ways to go about getting the air out. The 'factory' way is to take it to a shop where they can cycle the ABS unit with the car on the lift. The poor man's way is to get it up to speed and romp on the brakes to engage the ABS (if you can get enough pressure).

I took the car out and got it to around 40 mph and slammed on the brakes. I did this 3 times. I noticed that one of the wheels on the drivers side is locking-up and skidding. Should I bleed the brakes again since I've done this?

[KimMG]

How old are the flex/rubber brake lines?

[wvkeith]

Originally Posted by KimMG

How old are the flex/rubber brake lines?

I'm not sure, but they appear in good condition. I did replace the steel line going to the right rear wheel because it rusted through and was leaking. I'm starting to wonder if some air was introduced into the hydraulic control unit.

[KimMG]

Flex lines deteriorate on the inside. They will internally fail causing blockages that act like one-way valves not allowing the brakes to release.

[Ironmike215]

i'm not sure if you have a brake booster (for assisted braking) but if you do, you might want to check into that as well, it may be leaking internally (vacuum) or possibly frozen (hydraulic). just a thought.