Ewwestsr

Had a vacuum leak in the booster, had barely any brakes then, replaced booster and check valve, same amount of brake pedal. Replaced calipers today, completely bled system til fresh fluid came out. No brakes at all now.
Bad master cylinder?
Bad abs controller?
95 grand Cherokee 5.2l

Ewwestsr

Ok. So here's an update:
pulled 'new' vacuum booster from firewall, nothing out of ordinary; checked wiring to abs; resealed the master cylinder to the booster; bled brakes using 'one person way' with tubing and bottle, no air.
Stil​​​​​l not enough peddle, with engine running, to hold it. Can literally push the truck, in neutral, with pedal to floor. Can achieve enough peddle, with engine off, to turn off brake light switch.
Maybe another vacuum booster?
Any thoughts snyone?

dave1123

It may be something to do with the length of the pedal actuator rod. There should be specs for the length somewhere, it's just not something I've got in my mind right now. Try using your old one.

You can try a pressure bleed to get all the air out of the ABS unit. Also, did you bleed the air out of the master cylinder before you installed it?

caged

yep. pedal rod has a lot to do with it. experienced that with the wifeys tj once. you just have to remove it and adjust it many times till you get it right.

also, make sure the calipers are on the correct sides. common mistake, but make sure the bleeder is above the brake line.

mrshaft696

Have you tested the master? That would have been the first thing I did after replacing the booster.


What I would personally do if I were you....


Pull the line for the rear brakes, plug the hole, try the brakes.
Pull the line for the fronts, plug the hole, try the brakes...
If no brakes on both tests....
pull both lines, plug both ports try the brakes see if the master keeps pressure, if not its junk.