rear brake problems on 97 XJ please look!!!!

So my brakes started feeling like crap last week and i talked to my buddy and he said we'll look at em and see what is going on. So we tear into the rear drums and find a broken spring, trashed rear shoes, and a leaky wheel cylindar. after finding all this i figured well that has to be why my brake pedal is getting lower. So we replace everything! wheel cylinders, shoes, spring kit, drums, adjusters, everything. So we bleed the system, adjust the rears and i take for a spin. Hmm the exact same crappy pedal.

So i then figure well it has to be the Master cylinder. The pedal feels low and if you are holding the brakes and lift up on the pedal a little then push it in again and keep doing it you can almost work the pedal to the floor. well last night i pulled the MC and swapped in a new one ( after i cleaned the reservoir which was disgusting, looked like someone poured a cup of mud in it). Well now im 800 deeper into my XJ with all new brakes, new MC, new Hub bearings and it still has the same crappy pedal as before. One thing i found while bleeding the brakes is the front bleed as they should but the rears just dribble a couple little bit of fluid out each time. So something is clogged or something. I opened the line at the proportioning valve and it shot fluid out as it should so i moved further down the line to where the rubber line and the hard line meet and did the same. it also shot out fluid correctly. now im really confused unless the block on the rear end is clogged. any ideas??

i thought about doing that but i figured the brake system works at what 1000psi or better?? i was guessing that if the brake fluid wouldn't push it out how would some air?? i could be stuipid, wouldn't be the first time

DementedXJ said:

i thought about doing that but i figured the brake system works at what 1000psi or better?? i was guessing that if the brake fluid wouldn't push it out how would some air?? i could be stuipid, wouldn't be the first time

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you are right and wrong. yes there is high pressure in the lines, but its not like the garden hose flowing at pressure in one direction. the pressure builds up and flows back when the pedal is released, which is why crud collects at the end of the line (no pun intended ) blow out the lines, if your resevoir was full of junk i bet the lines are 10 times worse. good luck


-mike

clean out your proportioning valve it's probably plugged

Moral of the story: flush out your brake lines with new fluid every couple of years. Brake fluid is hygroscopic and will collect moisture over time. The water in the fluid will eventually cause crud to form and bad things begin to happen to the lines and cylinders. A couple bottles of fresh fluid poured into the master cylinder and bled through the system every other year is just good cheap PM.

I agree with ya Sand-Dog but unfortunatly ive only had this a couple years so im correcting all the neglect from the previous owners.

I am going to pull all the lines loose at the rear end and blow them out and rebleed everything and see what happens.

As for cleaning out the prop. valve. would that be just removing it and hitting it with brake clean?? or just flushing it with good fluid do it?? thanks alot guys

DementedXJ said:

I agree with ya Sand-Dog but unfortunatly ive only had this a couple years so im correcting all the neglect from the previous owners.

I am going to pull all the lines loose at the rear end and blow them out and rebleed everything and see what happens.

As for cleaning out the prop. valve. would that be just removing it and hitting it with brake clean?? or just flushing it with good fluid do it?? thanks alot guys

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I guess you bled the MC before you installed it, right. Some MCs need to be bled on the bench first where they are level. Otherwise they hold an air bubble.

falcon556 said:

I guess you bled the MC before you installed it, right. Some MCs need to be bled on the bench first where they are level. Otherwise they hold an air bubble.

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sure did.. thanks