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brake pedal to the floor...

13K views 26 replies 11 participants last post by  yj4x4 
#1 ·
jus replaced some brake lines and bled the brakes all the way around. when the jeep is off the pedal will pump up w pressure but when im driving the pedal goes to the floor if i jus press it one time. if im driving and pump the pedal i can get it to only halfway down but i gotta pump it a few times. any ideas on what might be causing this?

and yes, i tried using the search and only a few came up with this type of scenario.

if the master cyl has to be replaced are there any special tools i need to do replace this?
 
#7 ·
i cant remember the exact order but i did the rear ones first then the front.

i used a one person brake bleeder. u know, the manual one u pump up to pull the fluid through a tube into a container?cylinder.

when the jeep isnt running the brake pedal will keep pressure if i pump it, when its running the pedal will push all the way to the floor . if i pres the brake fast enough one of the wheels will lock up. i jus dont understand why its doin this
 
#6 ·
the pedal goes to the floor but doesnt stay there. it comes back up like normal. its jus that the brakes dont engage till all the way down. i bled all the lines and added more fluid. if its the master cylinder, is it hard to replace. im pretty handy, is it hard to replace urself? any special tools im gonna need? and i read another thread where someone was directed to bench bleed his lines. whats that?
 
#8 ·
usually u start with the farthest from the MC. if the m.c. is on the drivers side then you start passenger side rear, drivers rear, pass front, driver front. and vise versa for the m.c. on the other side
 
#13 ·
yah, it comes with a pump u use w ur hand and a vacuum thing on top that u can see how much pressure u r building , some clear tubing and a reservoir and some fittings to go on the bleeder nipples on the brake calipers. so when u pump up the pressure and crack the bleeder nipple on the caliper the pressure gets released and draws fluid from the caliper into the res. u tighten the nipple and then repeat the process till all the air is drawn out.

even before i replaced the lines the brakes always were low . the pads have good thickness in them all the way around but now the pedal goes to the floor on occassion.

im about to pull the master cylinder and bench bleed it or at least attempt to. what i wanna know is , after u bench bleed it, then reconnect the lines am i gonna get air in them all over again? and am i gonna have to rebleed the whole system again to get the air to come out from all the way up near the master cyl ?

i really need to get this problem solved beforer it starts snowing.its so frustrating
 
#14 ·
Yes, anytime you work on the brake lines, you need to bleed them. Get a new MC, fill it up on the bench, (they give you instructions with the new one) slap it on, and have a friend come over and help you bleed the brakes right. I have tried those 1 man bleeders, and found them useless.
 
#15 ·
You've still got air in the lines.
 
#16 ·
ok, heres another symptom. with the jeep off, i can pump up the pedal and get pressure but if i leave it for about 30 seconds i have to pump it up again. if the jeep is running , every time i go to brake i gotta pre pump it to get pressure in order for the jeep to stop like normal. if i brake hard and fast then sometimes i can get the jeep to stop like normal and even lock a wheel up. are these symptoms an indicator of one part or another going bad? (brake booster or master cylinder)
 
#21 ·
I have been reading this post,and can't believe your problems. But if you just do as SKEETER has suggested, and bleed the system of all air . You will have a full pedal. You can waste your money on whatever parts you want to . But the final answer will be to BLEED the system of air. Good luck,
 
#22 ·
yup im with gcssr, ive bled alot of brakes and it sounds like there is still air in the system. To bleed them right really takes two people so get a buddy that knows a little about it and have them help you and save your money on the m/c cause thats not the prob. If you go to a parts store sure there going to tell you its the master cylinder just to make some money and get rid of you.
 
#24 ·
yeah but if there spongy they will go to the floor. no one ask him if they felt spongy but im sure he had some pedal but not enough to keep it from pressing all the way to the floor. heck I dont know thats just what i thought.
 
#25 ·
well, i guess whoever said i ddnt need a mast cyl was right. im gonna try and bleed it again this weekend. the pedal still sinks to the floor if i dont pump it up. it feels pretty firm if i pump it up w the engine off. but once its running i lose pressure and it sinks to the floor when i press it. if i pump it tho i will get some pressure back , only temporarily
 
#26 ·
ONLY

When you bleed the system, be patient, it takes a while to do it right. Remember to keep the m/c resevoir full at all times, start at r/r,then l/r,then r/f,last l/f. Keep in mind to fill resevoir. If there is still a soft pedal , bleed again, sorry you baught a m/c, but you live and learn. Hope you all the best.
If you need help, ask and someone will respond .

Grant
 
#27 ·
I had the problem where the front brakes would lock up when i went backwards. but when i went forward i could barely stop. it turned out that i have a leak on the back brake system somewhere and the MC front resivor was empty. i thought i saw both where full but only the back resivor was full. it could be a bad MC
 
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