brake question

recently acquired a 1990 taurus, 74000 miles on the car. the brakes appeared good however after a week of driving the vehicle, the brakes have gone bad. when i step on the brake pedal it travels almost to the floor before any braking occurs. it will not pump up, however when the engine is off the brakes pump up and their appears to have brakes. when the ignition is turned on the brake pedal goes down and i am unable to pump them back up. i also hear air(at the pedal) as i pump up the brakes with the engine on. any help in diagnosing this will help. i am going to bleed the brakes this morning to see if it is air in the lines. thanks edsel....

Hi there, I would like to start by saying that I am not a mechnic by any means. But do the work on my cars my self. But I had a Olds cuttless back in the 90s and had some thing very close to what your experiance and it was the master cyclinder. A easy fix on the olds. But dont know on the taurus. I wont know untill I have to fix it.

Good luck

Keep an eye on your fluid, sound like there may be a leak somewhere. Given the miles on the vehicle, sounds like it may have been sitting for a while and either a caliper piston seal or rear drum wheel cylinder may have dried up and is leaking.

when i got the car last week i checked and filled up the brake fluid. it has remained filled since even with me pumping the brakes. funny checking the trunk i noticed several bottles of brake fluid making me suspicious at the time, however there does not appear to be any fluid loss?

Yeah, several bottles is not a good sign :lol2:

If it's holding, then maybe jsut try completely flushing out the system and getting fresh fluid in it. I'm still sticking to my guns about a dried up seal possibility tho. Sometimes it takes the right stiuation for the fluid to begin to seep out.

your probably right but it is funny because the brakes hold when i pump them up with the engine off. when i turn on the engine the brakes go down?

The brakes will pump up with the engine not running because you do not have to overcome the vacuum assist. When the engine is running, the vacuum makes the pedal a lot easier to push down. I agree with a master cylinder, but also check inside the power booster to see if there is any fluid in there. If fluid is inside the booster, replace booster also.

And judging by the age of the car, if you replace the master cylinder (and possibly brake booster) you really should flush the entire braking system.

If your Taurus has anti-lock brakes (ABS) then you will want to make sure you get fresh fluid circulated through the ABS pump as well before the valves corrode and prevent the ABS pump from working.

-Rod

replaced master cylinder and i'm rolling!!! thanks.....