REPLACED MASTER CYLINDER, HAVE BLED BRAKES ALL DAY, STILL HAVE A SOFT PEDAL???? on 2007 Kia Rondo

CUSTOMER HAS BEEN DRIVING VEHICLE WITH SOFT PEDAL FOR A COUPLE OF MONTHS, HE HAS BEEN PUMPING THE BRAKES TO STOP.

BROUGHT VEHICLE INTO SHOP AND CHECKED OVER, PEDAL IS SOFT, IF YOU PUMP IT SEVERAL TIMES, IT HOLDS BREIFLY AND THEN FADES AWAY, THE REAR BRAKES WERE JUNK, THERE WERE CHUNKS OUT OF THE ROTORS, REPLACED REAR BRAKES, THERE ARE NO LINES LEAKING ON VEHICLE, REPLACED THE MASTER CYLINDER WITH A NAPA MASTER CYLINDER.

I HAVE TRIED TO BLEED IT OUT ALL DAY, I HAVE USED MY SNAP ON SCAN TOOL, STILL BLEEDING AND DRIVING, BLEEDING AND DRIVING, ANY HELP WOULD BE APPRECIATED.

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5 answers 8 comments
Hi Pushrod,
reading your comments I was able to find an issue on one of the calipers after replacing the master cylinder twice and after bleeding the system several times, thanks!
It's 'old school' but still works like a charm... You're welcome, thanks for the reply!
did you bench bleed the master cyl before you installed it
YES, I DID, AND I'M AN AUTO TECH, I BLED THE BRAKES IN THE SEQUENCE THAT IT SAYS TO DO IT IN, RR, LF, LR, RF, BUT CAN NOT GET THE REAR BRAKES TO BLEED OUT.
Sorry i didn't read your profile,with a pinch off tool clamp the flex(rubber) lines closed,
now try the brake,full pedal? Do this on every line until you find your problem area
May have to clamp all lines at once.IF you do this test,you WILL find the problem!!!
Do this on ALL lines even if you think it is something else it works every time.
OK I DID THIS PROCEDURE AND FOUND THAT THE RIGHT FRONT CALIPER IS THE PROBLEM, AND OF COURSE NOTHING IS OPEN NOW, IN THE MORNING I WILL CALL THE DEALER AND SEE WHAT I CAN FIND, UNITED AUTO SUPPLY AND NAPA DO NOT HAVE ANYTHING AVAILABLE.

THANKS FOR YOUR HELP.
Remember this test cause i don't share it with everyone. Now look closely at
the RF. caliper and pads make sure everything is installed right. I have seen
brake pads installed in such a way that they would flex and let the pedal
travel to much. Check EVERYTHING caliper guide pins ect.Something is
shifting on the RF brake causing brake pedal to feel spongy.
good job wetry
WE TRY !
Thanks.
Hi JAY313622!
Could you please explain the issue with your front caliper?

I have got this issue with my Mazda3 2009 for three months, replaced master cylinder three times, also replaced vacuum booster, and installed new pads.
Your feedback woulfd be highly appreciated!
Time to go to see the doctor. Visit a mechanic to see what you are doing wrong!
Awesome trouble shooting procedure, I have had the exact same problem (though not as Sevier as Jay's) for four years on my 2006 KIA Sorento. I replaced the master cylinder vacuum bled all my brake lines as per the recommended bleed procedure and the brake petal bottoms out. The issue occurred after I replaced the rotors and pads. I bled several quarts of brake fluid since. I will try your recommended procedure and let you know....
If performed correctly, that test is bulletproof and WILL lead you to the problem every time!