brake problem with an 88 XJ

me and my brother are working on my 88 XJ, and we seem to have a weird problem with the brakes

when we hit the brake pedal, it easily hits the floor without any problem.. we first thought it was the master cylinder - so we replaced it, bled the brakes, no air in the lines at all now but still no go - we then replaced the booster behind the master cylinder, bled the brakes again, still hits the floor no problem

we've replaced:
master cylinder
booster
shoes/pads
the cylinders in the drum brakes in the back

we're still hitting the floor with the pedal, there's no pressure at all.. something i noticed is it's not as bad when it's off, but as soon as i turn it on its very easy to hit the floor with the pedal

any idea what could be wrong with it? im running out of ideas - only thing i can think of is the reconditioned master cylinder being bad

did you adjust the rear brake so theres a light drag on the drums? how much bleeding did you do? also did you just get this or did you guys have it then the brakes went bad?

yes, we adjusted them. we tried bleeding them manually at first, then we bought the kit from advanced auto and used the pump, and we didnt see any air coming out at all.. gone through a lot of brake fluid this was originally his vehicle, then i bought it after he got a newer 2000 XJ. it hadn't been driven in a few months, and we noticed it when we took it out for a bit, so we thought it was the master cylinder :doh: only thing i can think of at this point is the reconditioned master cylinders bad - but i have no idea

Did you bench bleed the MC before installing?

would'nt be the first time someone got a bad rebuilt

Garry

Rust Heap said:

Did you bench bleed the MC before installing?

Click to expand...

X2 this is very important.

yep, we bled the mc before installation

That kinda sounds to me like an air bubble in the M.C. or in the proportioning valve. Had that happen to me once. Serious pain it was to find but once I got the prop. valve burped, I had great brakes. Good luck.