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skunkhome
USA
12824 Posts |
 Posted - 07/16/2014 : 21:53:52
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My daughter drives a 1996 Honda Civic that has been in the family since new. In general it is in pretty good shape and only has about 140000 miles.
She complained last week that the brake pedal felt funny and seemed to sink while waiting at lights . I test drove it and it stopped sure and true and the peddle seemed steady. I checked the pads and shoes and they were well within limits. The next day I was driving the car and I experienced what my daughter was had reported. At lights the peddle will settle and you have to press harder to keep the vehicle stationary. You can release the peddle and press again and it will catch and hold for a bit but then sink again. When stand outside and my daughter works the peddle I can hear the RPM increase 50 or so RPM. I think I have it figured out but would like to have your input. |
  Phil
"They that can give up essential liberty to obtain a little temporary safety deserve neither safety nor liberty."
Benjamin Franklin |
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oldron
USA
2732 Posts |
Posted - 07/16/2014 : 22:08:35
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| My guess,leak in the Hydravac or what ever they call the power brakes now. |
 'Life isn't about how to survive the storm, but how to dance in the rain!' |
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B-16_IC
USA
2823 Posts |
Posted - 07/16/2014 : 22:13:32
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Generally I diagnose sinking pedal as a leaking master cylinder. But with this newer stuff I am open to other explanations. Of course that's where I would start. |
Life is all about paying. Pay attention, or pay the consequences, the choice is yours. Rich |
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Cvans
USA
4405 Posts |
Posted - 07/17/2014 : 00:31:28
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I have to agree with Rich. Master cylinder would be my first guess.
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East Central South Dakota
The democracy will cease to exist when you take away from those who are willing to work and give to those who would not.
Thomas Jefferson
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olcowhand
USA
5115 Posts |
Posted - 07/17/2014 : 13:01:08
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| I vote master cylinder as well. The slight rpm change is kind of normal as the booster bleeds off vacuum. |
Daniel in Ky -- So much to do, so little time!
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skunkhome
USA
12824 Posts |
Posted - 07/17/2014 : 21:07:28
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| Thanks guys. I thought it was the booster. |
Phil
"They that can give up essential liberty to obtain a little temporary safety deserve neither safety nor liberty."
Benjamin Franklin |
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allisstuff
40 Posts |
Posted - 07/18/2014 : 17:53:09
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quote:
Originally posted by skunkhome
Thanks guys. I thought it was the booster.
If it was the vacuum booster loosing vacuum, the pedal would get hard but it would not sink/drop towards the floor. Master cylinder would be a likely cause, but pull the wheels and see if the caliper piston dust boosts are bulging. If the caliper piston seal is leaking fluid, it will leak past the seal into the dust boot causing them to bulge.
Also, make a check of all the brake lines and brake hoses to make sure you don't have a brake fluid hydraulic leak. A leak will cause the pedal to sink also.
Regarding your comment about having to push harder to hold the vehicle stationary. I would expect that if you had an internal leaking or bypassing master cylinder or an external leak, once the affected master cylinder circuit bottomed out, it would not be able to generate any additional pressure in that circuit and if there is a leak, the pressure in that circuit would drop to near zero, than you would then be working on a half system, where only two wheels, likely opposite diagonal brakes, would be functional and the pedal effort would likely double. |
Edited by - allisstuff on 07/18/2014 17:59:28 |
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wlewis379
USA
402 Posts |
Posted - 07/19/2014 : 12:28:10
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You may want to check the abs sensor. Very common problem in ford Rangers. I have replaced them in the 2 rangers I have owned.Dirt collects in the sensor ring and blocks the sign wave to the senor pickup. You may be able to flush the ring out with brake cleaner by removing the sensor and spraying brake cleaner through the sensor housing. I have done this a few times with good results.
cheaper than buying a new sensor.
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Happy Trails Bill
Insert Image: 
People who are all wrapped up in themselves are overdressed |
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BRAD1975
Canada
1562 Posts |
Posted - 08/06/2014 : 22:50:49
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well im a bit late at seeing this but my first checks would be for leaks
then id do a pedal test....slow pedal pushing and fast pushing
if it stays hard after a sharp press but soft bleed down on a slow press i would think its the sealing cups in the master
bad booster will usually make an easily heard vacuum leak hissing sound inside the passenger compartment
so is it fixed?...what did it end up being?
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Need help from automotive gurus
