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Soft brake pedal, firm on second pump. What's wrong?
I have spongy brakes on my '08 EL using about half of pedal travel. The second pump uses about 1/4 travel. My mechanic tried to bleed the brakes of any air but it didn't help. There is no leaking brake fluid. I'd like to get sorted out before heavy towing.
Anyone have an idea if this has to still be air in brake lines, master cylinder seal issue or something else?
Last edited by ericjacobsen3; 03-27-2012 at 02:47 AM.
Reason: typo
I agree it would appear I have air in the system. However, I would think that air in the system would be soft on the second pump, not firm like I am feeling.
Agree?
For the alternate theory that "some of the Expy/F150 just have mushy brakes: I have a hard time believing a 1 million unit per year platform has brakes that cannot be made to work consistently.
I hate to say it, but it would seem to me that this is a bad master cylinder seal that doesn't push against the cylinder wall until extra pressure from a first pump pushes it to seal. Does this make sense based on the design of the master cylinder seals (no idea what they really look like)?
I have the same problem on my '11. Brakes work fine but sometime when you just press the pedal it will almost go to the floor very lightly. Then you press it again and it is rock hard.
I have spongy brakes on my '08 EL using about half of pedal travel. The second pump uses about 1/4 travel. My mechanic tried to bleed the brakes of any air but it didn't help. There is no leaking brake fluid. I'd like to get sorted out before heavy towing.
Anyone have an idea if this has to still be air in brake lines, master cylinder seal issue or something else?
There is an air bubble floating in the system.....they can be stubborn, sometimes taking days to get out.....Highly recommend the use of a pressure bleeder (not the mighty mite, etc, a professional spec unit).
Now if....you hold your foot on the pedal and with the engine running is slowly drops, then you have a master cylinder issue.
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Member: Never trust a person over 40 who drives a Chevy club
Flatheads ain't so bad!
Certified backyard mechanic I & II
When you say it takes days to get a bubble out, do you mean the vehicle brakes are open for bleeding? If you mean just wait with the car in service, I have been waiting 8 months and nothing has chnaged.
When you say it takes days to get a bubble out, do you mean the vehicle brakes are open for bleeding? If you mean just wait with the car in service, I have been waiting 8 months and nothing has chnaged.
I remember my dad had a chev back in the early 60's, he worked for hours bleeding the brakes and could not get the "bubble" out, ended up taking to a brake shop, took them 3 days bleeding with a pressure bleeder in different methods befor finally getting the air out.
__________________
Member: Never trust a person over 40 who drives a Chevy club
Flatheads ain't so bad!
Certified backyard mechanic I & II
I have the same problem on my 07 expy and also had the same problem on my 07 sport trac that I got rid of. the sport trac I bought new and I had it back to the dealer 5 or 6 times they bled the brakes, replaced the front calipers, replaced the booster and master cyl, and did a tsb on the brake pedal, nothing helped. finally at 24k miles the rear brakes were worn down and I was about out of time on the warranty so I traded it in, but I thing that it might be something in the brake bias in the ABS unit. I think that we are stuck with the problem. I just bled the brakes on my expy and i dont think that it helped.
__________________ 07 Expedition XLT 4x4 66 F-100 (work in progress)
Im not sure if your truck has it but our Navigators breaks are horrible if the pedals are adjusted all the way down. If you have the pedal adjustment than raise them more.
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