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  • Air in the lines?

    My other half tells me there is air in my brake lines. We have now spent 3 days "bleeding" the brakes. We did caliper rebuilds, the rear cylinders are new, replaces all brake lines except the tiny (skinny) one that goes from the front to the back.

    The brakes definitely stop the scout..but the other half can't use them with-out causing the scout to stop violently, and sort of "bounce". Well I've watched from outside, the wheels don't bounce, the body bounces and rocks.

    Anyhow, he says he can feel the air in there.:(

    How am I supposed to get this air out? (Oh, I don't have this problem, but the theory is that I have been driving this vehicle so long, I subconciously compensate or something?)

    Oh, and is the line going to the back supposed to be that tiny?! It is maybe an eighth inch?

    Anyway, I am at a loss:confused: . What could be wrong with this thing?

    Oh, when we bled the front, the fluid squirted out, no air. When we bled the rear, it just dribbled out like "spittle", but still NO AIR?

    :confused: HELP?! I won't be driving this until I fix whatever is wrong.

    possum scout

    p.s., the master cyl. is new too.
    Last edited by possum scout; 03-07-2003, 11:58 AM.

  • #2
    Couple of times I built brake systems from scratch and found several bleeds in order. Course a power bleeder is the way to go.

    Start by bleeding the front left, then front right, then left rear then right rear. Don't pump, pump, pump. Make sure the master cylinder is full and hold down steady while opening bleeder till the brake pedal hits floor and close. Evacuate the hole line of air and foam.

    There is also a button on the regulator (left fender well) that must be pulled out (or pressed in) while bleeding the fronts.

    Also adjusting the rears properly will help with a better feel at the pedal.

    Hope that helps!
    [CENTER]1994 Buick RoadMaSSter Estate Wagon LT1/4L60E. White and Woodgrain Sleeper...PCM 16188051 With SS/V4P/Custom Tune! WOT 12.9 AFR!

    1990 Chevy Suburban Silverado 5.7L 2wd ECM 1227747 HiWay Lean Cruise 18.5 MPG and 12.5 to 1 AFR at WOT!

    1972 IH 1210 Isky Cammed Balenced 345 4 speed PCM 16197427 Project!

    [SIZE=3][B][URL="http://www.gearhead-efi.com/"]GearHead-EFI.com[/URL] EFI Conversions and Chip Tuners![/B][/SIZE]
    [B]May be all you need to know about EFI![/B]

    and I still help local JustIH members (for fun) free! :cool: [/CENTER]

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    • #3
      Thanks for the info.

      Well, we worked on it some more, but now I think it's worse?!Anyway, now when the vehicle is off, the pedal just "gives" until it get real stiff at the bottom. It used to go "hard, spongy, hard"

      Anyhow, I was in the back seat when the other half decided to try the brakes out....OUCH. I think I got whiplash of the spine!

      Anyway, he says that he couldn't help it, that my brakes are "spongy"?

      What causes spongy brakes and how do I fix it?

      Also, do other types of braking system "feel" different from the way Scouts do? The other halfs rig has 4 drums, and the other car he drives has 4 wheel disc., anyway he says my rig should "feel" like his.

      I just can't tell?! I know they feel "weird" now though!

      possum scout
      :eek:

      P.S. The other half informs me that my proportioning valve came from a chevy S10? Does that make a difference? He says it was the same thing, so he put it in for me? My old one was broken. He says the needle in it was destroyed?

      He says, he had taken my Scout out, noticed the brakes didn't "feel right" and decided to surprise me by fixing them. He noticed the broken prop. unit and replaced it with one from an S10, but he says it didn't seem to make any improvement?
      Last edited by possum scout; 03-08-2003, 12:48 PM.

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      • #4
        Spongy brakes are a sign of air in the system. Bleeding them is the only way to fix it.

        Cars and trucks all have slight differences in feel just because of design but they should all feel firm, not spongy.

        Another trick while bleeding to save fluid and avoid air going back if the person pushing the pedal lets up a little (lets air back) is to use a clean glass jar with some fluid in the bottom. Clean the bleeder and put a piece of clear hose over the bleeder into the glass jar to the bottom under the fluid level. Now when you bleed you can see foam or air coming out. Stop bleeding when it is clear. If you run the master cylinder out of fluid, start again. When the excess fluid settles (no bubbles) reuse it.

        Question? Did you replace the master cylinder? If so did you bleed it before installing it?

        Sorry about the whiplash!
        [CENTER]1994 Buick RoadMaSSter Estate Wagon LT1/4L60E. White and Woodgrain Sleeper...PCM 16188051 With SS/V4P/Custom Tune! WOT 12.9 AFR!

        1990 Chevy Suburban Silverado 5.7L 2wd ECM 1227747 HiWay Lean Cruise 18.5 MPG and 12.5 to 1 AFR at WOT!

        1972 IH 1210 Isky Cammed Balenced 345 4 speed PCM 16197427 Project!

        [SIZE=3][B][URL="http://www.gearhead-efi.com/"]GearHead-EFI.com[/URL] EFI Conversions and Chip Tuners![/B][/SIZE]
        [B]May be all you need to know about EFI![/B]

        and I still help local JustIH members (for fun) free! :cool: [/CENTER]

        Comment


        • #5
          Yes we bench bled the master cylinder, followed all the instructions that came with it.

          Now I am going to replace the front brake line. The other half "repaired" it with a "feral"?spelling? When we lowered the brake lines, one was broken. Now I am thinking I had better just get a new one.

          He says he doesn't see any leaks, but there is so much crud etc....I don't think we could see it even if it were a gusher!

          We have to tote our own water out here, so the scout hasn't had a "bath" in about 15 months!

          possum scout

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          • #6
            If your talking about the rubber hose on each side as being the brake line?

            Yes! Your lines if original are way overdo to be replaced.

            Yes! They get old and soft from being covered in power steering oil usually and will give a spongy feel.

            Did you lower the front brake lines because of a lift?
            If yes I would re think what you did and put it back properly and then just bolt on extended lines from Skyjacker or others. They are stainless braid looking and have a very firmer feel. I had the local hose maker re-build mine at six inches over stock. Two in front and one in back. Other than having longer better lines my system is stock and still works great with 33's.

            You have to be very careful at what you do here, re-designing brakes could be, well Not Good!

            Should be easy to find leaks out that dusty road!
            [CENTER]1994 Buick RoadMaSSter Estate Wagon LT1/4L60E. White and Woodgrain Sleeper...PCM 16188051 With SS/V4P/Custom Tune! WOT 12.9 AFR!

            1990 Chevy Suburban Silverado 5.7L 2wd ECM 1227747 HiWay Lean Cruise 18.5 MPG and 12.5 to 1 AFR at WOT!

            1972 IH 1210 Isky Cammed Balenced 345 4 speed PCM 16197427 Project!

            [SIZE=3][B][URL="http://www.gearhead-efi.com/"]GearHead-EFI.com[/URL] EFI Conversions and Chip Tuners![/B][/SIZE]
            [B]May be all you need to know about EFI![/B]

            and I still help local JustIH members (for fun) free! :cool: [/CENTER]

            Comment


            • #7
              rear brakes?

              If you just got a little spittle coming out the rear you might have some rust or something plugging a line.
              If you pump the brakes and hold them and open the bleeder valve it should do more then just a little spittle if i dont get a good solid stream im looking for either a bent(kinked) line or one that looks rather rusty to replace. Ive even found lines that look good on the outside hold a plug of rust on the inside.

              Comment


              • #8
                Travis,
                I have always bled my systems by starting with the slave cylinder closest to the master and working out from there. It would be left front; right front; left rear; finally right rear. I have one of those inexpensive hand vacumn pumps that really make it an easy process.
                Mickey

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