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Possible ABS Problem? 900 1996

posted by  LUV MY 960 on  Fri Oct 28 08:50 CST 2005
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Hello, first time poster here. I have a '96 960 with about 84,000 miles on it. I just got it about three months ago, wish I had read about all of the 960's problems beforehand, but I test drove it and loved it over the S40 I was also considering. I have had to replace the radiator, because the plastic neck broke off, $250 & 1 day DIY, done. No I have this Braking Problem that showed up about three weeks later... I will try to explain this as simply as possible, press the brake petal once, you are ok, remove foot and try to brake again, nothing. BUT... If you press gas and go back to brake it works again, but like before if you remove your foot and try to press again, nothing. Now the strange part, that has gone away and now when you press brake petal it is so stiff that I have to put all of my 250 LB behind it to even get it to stop in a long distance. It is definately nolonger safe to drive. The brake fluid resovoir is full, all ABS related fuses I can find seem intact. ABS light came on at the very begining, but quickly went off and was never heard from again. Any suggestions on what to look for or at next?

Thanks for any help!








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    Possible ABS Problem? 900 1996

    posted by  LUV MY 960 on  Fri Oct 28 10:31 CST 2005
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    OK, I read that post. Upon reading I realize I forgot to say that I too can hear what seems like a hissing air leak noise coming from the petal when it is applied, would this make a difference? Also one major thing before I try all of these tests, Where is all of this stuff located? Brake booster and such? Thanks...








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      Possible ABS Problem? 900 1996

      posted by  LUV MY 960 on  Fri Oct 28 12:25 CST 2005
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      Ok, the Vacuum pressure is increadible when I pull the valve from the brake booster. It is pulling pressure from the booster, is this right? Also there was a vaccuum leak spurring from a split rubber connector on one of the white vaccuum lines. I replaced that, there is no difference whatsoever. Any ideas?








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      Possible ABS Problem? 900 1996

      posted by  KlausC on  Fri Oct 28 10:54 CST 2005
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      last visit: Fri Oct 24 10:15 CST 2014
      [RELATED]

      Open the hood and on the drivers side near the steering wheel, you will see a large round cannister. That's the brake booster. Forward of the cannister is the brake pump with the little bottle of fluid on top.
      The vacuum line from the booster goes to the engine. The check valve is either as pictured in the previous post, or inline with the vacuum line. It's just a plastic piece.
      The booster can be repaired or replaced from a junk yard sample. $500 is not in my lexicon.

      Klaus
      --
      (1975 164, 1995 854T, 1998 V70R)








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    Possible ABS Problem? 900 1996

    posted by  someone claiming to be tjts1 on  Fri Oct 28 10:26 CST 2005 [RELATED]

    It sounds like the brake booster one way valve. Cheap and simple fix. It is the white knob in between the brake booser and the one hose coming out of it. Looks like this.

    Hard Pedal Problems and Brake Booster Diagnosis
    And don't let the FAQ scare you. There is a lot of misinformation about the 960 on there. Congratulations on the new car.
    Good luck
    Justin








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    Possible ABS Problem? 900 1996

    uid 6573's pic
    posted by  javalion on  Fri Oct 28 10:14 CST 2005
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    last visit: Wed Jul 23 09:57 CST 2014
    [RELATED]

    This sounds like a brake booster problem which uses vacuum from the engine to get the 250 pounds down to 2 pounds. One of several things, leaking or detached hose, the one way valve is not one way any more or the diaphragm in the booster is bad. Most likely a hose leak or a bad $9 one way check valve.
    http://www.brickboard.com/FAQ/700-900/Brakes.htm#BrakeBoosterandCheckValveDiagnosis
    --
    Tom F. Three Bricks, maintain two more.








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      Possible ABS Problem? 900 1996

      posted by  LUV MY 960 on  Sat Oct 29 07:02 CST 2005
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      One way check valve operating fine. there was a vaccuum leak at one of the connecting black rubber elbows that was old brittle and had a hole in it, fixed that to no avail. any other suggestions?







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        Possible ABS Problem? 900 1996

        uid 6573's pic
        posted by  javalion on  Sun Oct 30 02:59 CST 2005
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        last visit: Wed Jul 23 09:57 CST 2014
        [RELATED]

        This is what I think is going on. Inside the brake booster there is a diaphragm. With the brakes not depressed the vacuum is equal on both sides of the diaphragm, other wise the brakes will always be on. When the brake pedal is depressed another valve opens and (higher) atmospheric pressure enters on one side of the diaphragm (the brake pedal side) thus forcing the pressure to the master cylinder. The reason why you have such good vacuum when you remove the one way valve is that the system is totally closed when the brakes pedal is not depressed. The whooshing sound you hear when you press the brake pedal is excessive air rushing in and through a hole in the diaphragm.
        --
        Tom F. Three Bricks, maintain two more.








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          Possible ABS Problem? 900 1996

          posted by  poolman on  Sun Oct 30 10:24 CST 2005
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          last visit: Sun Dec 26 02:03 CST 2010
          [RELATED]

          Javalion has probally hit your problem square on the head. If you pulled the one way valve and had lots of vacuum escape while doing so,the booster is probally OK.
          Now the brake master cylinder is suspect.
          Hope that helps
          Poolman








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            Possible ABS Problem? 900 1996

            posted by  poolman on  Mon Oct 31 13:33 CST 2005
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            last visit: Sun Dec 26 02:03 CST 2010
            [RELATED]

            I'm dreadfully sorry for the post about the brake master cylinder being bad,jumped on the wrong part,yes the booster can hold vacuum and still be bad,they can be rebuilt though, guy fixed mine in old car I restored few years back,Booster Dewy,check his website. Ran about 100 bucks and did a great job. Or you can probally get one from a pic and pull. Erie Vovo (thats how it's spelled) website would have one available as well, used but reasonable.
            Hope that helps
            Poolman








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        Possible ABS Problem? 900 1996

        posted by  poolman on  Sat Oct 29 11:41 CST 2005
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        last visit: Sun Dec 26 02:03 CST 2010
        [RELATED]

        Get a peice of vacuum hose about three feet long of fairly large diameter. Take the hose and put one end to your ear and the other end down where the hose for the brake booster hooks to the intake manifold. With the engine running try and see if you can hear air rushing or maybe better air escaping. You may want to take the hose off and inspect it, if you hear air moving after doing what I just discribed. Vacuum leaks are tough to pinpoint sometimes,but they sure will make a difference in the way your car performs after their fixed. Stick with it you'll have brakes again soon.
        If you find that there isn't a vacuum leak down around the hook up I mentioned, have someone step on the brake peddel while it's running and see if you can tell with the hose to your ear where the leak is coming from.
        If it turns out the booster is just bad,I would try a used booster from a pick and pull before going for a new unit from the dealer, very rare for a booster in one of these cars to go out so young in years.
        Hope that helps
        Poolman







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