Brake pedal goes to the floor sometimes

Tiny
GEORGE PORTS
  • MEMBER
  • NISSAN SENTRA
1997 nissan sentra GXE 150,000 miles. Not sure of engine size.
Brakes seem fine on my way to work in the daytime (30 mile drive on the freeway). On my way home, (at night with lights on) the pedal will go all the way to the floor and I have to pump them a few times to restore the braking capability. The pedal will be real hard on the first pump if I apply more gas at the same time. If I coast and pump the brake, it takes at least 3 or 4 pumps to get the pedal to funtion.
I had the master cylander replaced which didn't fix the problem.
Any help would surely be appreciated.
Thanks,
George Ports
Wednesday, September 12th, 2007 AT 10:15 AM

2 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
George first let me ask if anything other than the master cyl was replaced, like brake shoes or pads? If the pedal sinks at all, there is a leak in the hydraulics.
The easiest way to find it is to clamp off the brake hoses with brake hose clamps, then as someone holds the pedal, remove them 1 at a time, when you get to the bad wheel the pedal will sink when the clamp is removed.
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Wednesday, September 12th, 2007 AT 11:16 AM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
No the charge of the battery has nothing to do with the Vacuum booster! And George did you do what I suggested yet? I could keep anwering till you are happy, but it works better if you take the advice, use it then see if it works or not?
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Monday, September 17th, 2007 AT 3:08 PM

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