I just completed a brake job on my 89 f150 4x4. I replaced both front calipers, rotors, pads, rear shoes, drums and brake cylinders. I bled the brakes and got good fluid out of the rear brakes but could never get a good stream of fluid from the fronts. It doesn't sound to me like the master cylinder because of the fact that the rear brakes are working fine. Am I wrong in thinking that or is there something I am overlooking?

 

I'm no technician (famous last words, huh?) but it could be that there's some sort of debris or loss of prime in the front part of the ABS plumbing. I know those are some pretty small passages that it goes through and it doesn't take a very large particle to gum up the works. Perhaps a chunk of something fell into the resevoir when you were adding fluid?

Just my SWAG.

~Rob

edit: Nevermind the ABS thing.. I just saw you have an '89. Maybe it was a big chunk?

 

Post 1978 vehicles have a split brake master cylinder. The master is split front and back as completly separate brake systems with a common reservoir. This means that if you loose pressure on the front or rear you will retain pressure on the other. This was specifically designed this way so you would have some brakes and not a total brake failure.

You sure could have a bad master, but probably just need to bleed the system some more. Re-check brake line connections are tight as well as no kinked lines too. If a banjo fitting is loose it could be sucking air but not leaking fluid....same goes for the bleeder screws. Did you pressure bleed or just gravity bleed the system?

If no air is coming out of the lines when bleeding, clamp off all the soft lines with brake line clamps and check the pedal. Is it hard and high...if so your master cylinder is probably fine. If it falls you either have a bad master, a leak or air in the system.

Good luck...let us know what you found.

 

Thanks for the info. Turns out it was the master cylinder. Replaced it and everything bled out fine. I can now stop without using the Flintstone method.