1989 cougar-brakes locking with engine on?

[bigfartter]

I have replaced my front brakes,master cylinder and drivers side wheel cylinder.I have bled all the brakes starting with the furthest away from the master cylinder but i have not bled my master cylinder.I feel that I have bled them very well----but heres the problem.When I pump the brakes with the car off,they pump up very well,but when I start my car the pedal goes to the floor,and the front brakes lock.The pedal will not come up till the car gets shut off. Any help would sure be appreciated. There Is No Abs On The Brake System Could This Be The Booster or could the master cylinder be bad. this did not do this before I started working on the brakesbe appreciated.I am leaning toward the new master cylinder being bad,

[mikecox1]

Originally Posted by bigfartter

I have replaced my front brakes,master cylinder and drivers side wheel cylinder.I have bled all the brakes starting with the furthest away from the master cylinder but i have not bled my master cylinder.I feel that I have bled them very well----but heres the problem.When I pump the brakes with the car off,they pump up very well,but when I start my car the pedal goes to the floor,and the front brakes lock.The pedal will not come up till the car gets shut off. Any help would sure be appreciated. There Is No Abs On The Brake System Could This Be The Booster or could the master cylinder be bad. this did not do this before I started working on the brakesbe appreciated.I am leaning toward the new master cylinder being bad,

well sense you let the brakes run without bleeding the master cylinder you are due for a full break bleed. you can't replace the master cylinder without bleading it!...BAD i'm not here to judge i'm here to help. First bleed the master cylinder. (you can get a kit at autozone or any local parts shop with instructions) get it and use them. If you have any questions e-mail me at [email protected] i can get you back on the road mike

[bigfartter]

I had a brake bleeder screw broke off and was trieing to bleed the brakes through the line.I could not get the bleeder out.So the drivers caliper had air trapped in it,causing the passenger caliper to lock up no matter how many times I bled the brakes.So I replaced the caliper and got a new master cylinder with a bleeder kit,bench bled the master cylinder,bled all the lines and behold,Good brakes.what a pain in the booty.----thanks for your help!!!!!

[PJRichardson]

you did this to yourself!!!!

Now you know... YOU CAN BLEED THE BRAKE THUR THE LINES!!!!!