brake problem!11!11!

I posted a thread on here a while back about my problem and we determined it was the brake master cylinder.....I bench bled, then installed the M/C and then bled the lines. I realized that the rear brakes were shot so I replaced them also. then bled the brakes again. My brake pedal still sinks to right above the floor, and then it is really hard to push the pedal while braking, also sometimes I get in the jeep and have to pump the pedal to get brake pressure....any ideas on what I need to do to fix my problem?


Thanks in advance,
Chris (scarboy)

Year? Does it have ABS?

still air in the system.......bleed more.

My bad, its an 88 without ABS and with 160,000 miles. I hear a wooshing sound from the dash when the jeep is running and it stops when I push the brakes....I also have on bad wheelbearing.....

your power booster is bad, the noise you here is vacuum leaking-will cause all symtoms your describing. If the master was leaking past the rear seal, it probably ruined the seals in the booster. very common. pull vacuum hose off of booster I'll bet you'll see traces of brake fluid in there.

I must just add (my old refrain) that although the high effort and whooshing do indeed suggest a bad booster, a bad booster will not cause a low pedal or the need to pump. That is caused by something else, either a need for more bleeding, a leak, a defective master cylinder. master cylinder actuating rod passes through the booster from the pedal without interruption. Boosters fail safe.

There is still air in the lines need more bleeding that will help.

Another often overlooked problem can be your rubber lines. Ones that have been stressed from susp. flexing, crimped with vise grips while changing a caliper,or even just allowing the caliper to hang from the lines while working on the brakes can come apart internally, causing high effort-poor braking. Very hard to spot because they can look fine from the outside. often when replacing calipers on older/high mile vehicles,we try to sell customers these lines to avoid problems. as for soft petal, try gravity bleeding the system. Do this until you have new clean fluid at all bleeders. This will help make sure there is no moisture or air in the system.hope this helps