While driving brakes failed and the pedal went to the floor

Tiny
JBENTL01
  • MEMBER
  • 1998 DODGE CARAVAN
The brakes in my van just stopped working the other day. I left my home and they were fine. Two miles later they failed and the pedal went to the floor. I replaced the rear cylinders four months ago, but no problems until now. Any ideas?
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Sunday, September 21st, 2008 AT 9:42 AM

31 Replies

Tiny
RASMATAZ
  • MEMBER
Sounds like the master cylinder may be by-passing internally. This will happen sometimes when the seals inside become work and cannot always hold pressure.
See the guides below on this issue, they will help shed some light on what is going on and how to repair it.

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

See the images below for replacement of the master cylinder
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Sunday, September 21st, 2008 AT 9:51 AM
Tiny
BILL SHEA
  • MEMBER
  • 2000 DODGE CARAVAN
  • 850,000 MILES
The brakes on my van goes to floor replaced master cylinder and checked for any leaks and you bleed the brakes and it will last about four days and than they will go to floor again if you bleed them they will last again for four days.

I replaced master cylinder and checked for leaks if you bleed the brakes they will work for about four days than if you bleed them again they will last about four days again. The master cylinder never needs fluid?
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
KHLOW2008
  • EXPERT
Is the master new, used or rebuilt?
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
BILL SHEA
  • MEMBER
New.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
BILL SHEA
  • MEMBER
Brand new not rebuilt.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
KHLOW2008
  • EXPERT
If the system is not using up fluids and the master cylinder is new and bleeding works, this is something that requires some head scratching.

Check the booster to pedal push rod free play. Ensure it has a little movement of the pedal before the push rod moves.

If vehicle is equipped with ABS, it could be the one causing the problem.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
BILL SHEA
  • MEMBER
Is there a way to bypass the ABS?
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
DAWGTUFF
  • MEMBER
  • 1989 DODGE CARAVAN
  • 222,000 MILES
Brake pedal goes half way to floor, fluid is fine, pads are fine.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
SATURNTECH9
  • EXPERT
Have you checked to see if the rear brake shoes are properly adjusted? If there too far out of adjustment then it can cause a low pedal.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
KHLOW2008
  • EXPERT
You would need to remove the ABS control unit and install with a proportioning control valve. However, for some areas it is an offence to do such modifications so ensure you are not breaking the law by doing so.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
RASMATAZ
  • MEMBER
If there is no external leak and brake shoes adjusted and bleed properly-could be the brake master cylinder has an internal leak.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
KEN
  • ADMIN
Have you replaced the rear wheel cylinders? Air can sometimes get sucked in when releasing the brake pedal.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
ANGELA RICHARDS- JOHNSON
  • MEMBER
  • 2005 DODGE CARAVAN
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
Hi, our van has been to multiple mechanics. We had good brakes but our ABS was not working. Our mechanic put in a new ABS module now the ABS is working, but the brakes are horrible unless I pump them. We have changed the calipers, master brake cylinder twice because we thought the first one might be faulty. All rotors and pads have been replaced, bled out the system by three different mechanics and the brake lines have all been tested for leaks by a certified mechanic and no leaks. We do not know what to do now, any suggestions?

Thanks,
Angela
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
AL514
  • EXPERT
The ABS module has to be bleed using a scan tool that can command the solenoids open. There is still air in the system, pumping up the pedal is just building pressure temporarily. Common issue when the ABS mod. Is replaced. They need to be bled correctly.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
ANGELA RICHARDS- JOHNSON
  • MEMBER
The dealership said that they did that, they bled the ABS system and said they activated the ABS module and that it must be the master brake cylinder causing the problem. After replacing it again we had the same result.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
AL514
  • EXPERT
Then they diagnosed the problem wrong. After replacing the master you will have to re-bleed the ABS system again or you will still have air in the lines. They should have been able to repair this problem for you from the start. They are the most qualified techs for this vehicle. There should be no reason they are not directing you in the right direction. They are supposed to be the expert's.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
KEVIN SCHLARB
  • MEMBER
  • 1994 DODGE CARAVAN
Six cylinder front wheel drive automatic.

My sons' van. The other day he had no brakes, he put more brake fluid in but still no brakes. The master cylinder was leaking so I replaced it, but when I bleed the brakes, fluid came out in the beginning but now I get nothing unless you leave it for an hour or so then brake fluid will come out for one cycle of bleeding. Checked the vacuum on the power booster and it works fine. Could it be the power booster itself?
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
RASMATAZ
  • MEMBER
Did you bench bleed the new master cylinder?

Could it be the power booster itself?

To check the vacuum booster, pump the brake pedal with the engine off until you have bled off all the vacuum from the unit. Then hold the pedal down and start the engine. You should feel the pedal depress slightly as engine vacuum enters the booster and pulls on the diaphragm. No change? Then check the vacuum hose connection and engine vacuum. If okay, the problem is in the booster and the booster needs to be replaced.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
JALOPYPAPA
  • MEMBER
When you replaced the master cylinder, did your bleeding procedure include bench-bleeding the master cylinder before installing it? I have not done one of these. Or not in more than thirty years, anyway.

But I understand that before installing the master cylinder, you have got to put threaded plugs in the two outlets, fill the reservoir, open one plug, depress the piston, hold the piston there while your reinsert the plug and then release the piston. Then repeat the process on the other outlet.
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Monday, September 24th, 2018 AT 6:09 PM (Merged)
Tiny
TKS1
  • MEMBER
  • 1995 DODGE CARAVAN
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 200,000 MILES
When installing front pads on car, I used a C clamp to push the piston back. I did not open bleeder valve. After installing pads on both wheels, I looked at master cylinder and fluid was gone. Fluid all over engine compartment. Filled reservoir with fluid and tried to bleed brakes, Can not get a hard pedal. Did I damage ABS system and can I fix it? Have done brakes many times, never emptied a reservoir before, or had one spray fluid with such force. Will a power bleeder do me any good? I do have access to one.

Thank you,
Ted
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Monday, September 24th, 2018 AT 6:09 PM (Merged)

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