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R.L.Stockwell
Bone Stock
Posts:1
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| 01/31/2005 1:56 PM |
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| I have a 98 chevy Z71 4X4 and just did some major brake overhauling...M/cyl,rear whl cyl, rear shoes, frnt pads and Calipers...bench bleed M/cyl prior to install...Bleed entire system to evacuate old fluid....pedal firm when engine off, but running the pedal is excessivly soft...thought Vac Booster malfunction but tested good at shop....no codes per scanner check any Sugestions....[:(] |
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R.L.Stockwell
face58@hotmail.com |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 02/01/2005 7:03 PM |
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Sounds like there's still air in the system to me. I struggled with this on a few vehicles and ended up going through a couple large bottle of brake fluid to clear it out. Everything felt fine when pumping the brakes with the engine off, but sucked wind when the truck was running.
If you replaced the front calipers, make sure you didn't put them on the opposite sides on accident. What I mean is, make sure the bleeder screws are on the upper side of the calipers, not the bottom, otherwise you'll never get the air out of them - as an ASE cert mechanic, I made that mistake recently (not paying attention, too many libations, etc.) to my embarrasment.
You might want to try using a "Vacula" brake scavanging system. The good ones hook up to an air compressor and literally suck the fluid through, but the hand pump style work very good as well. This should ensure that you don't have any air left in the lines.
Rick |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
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'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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hvy55chvy
Bone Stock
Posts:6
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| 03/11/2005 4:19 PM |
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| Just bleeding til you see clear fluid ist always enough when dealing with late model brake systems especialy with ABS plumbed in. Put a few large bottles through the system with conventional home bleeding or let a shop put a vacula on your system. |
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davidmiddleton
Bone Stock
Posts:18
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| 03/11/2005 4:54 PM |
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| You may want to talk to someone at a chevy dealer to see if you need to do any speacial bleeding with the ABS system. GM has been known to have a few systems that you need a scan tool to bleed EVERYTHING once the system is open. This may not apply to your truck, but I used to be a GM tech and they do have a few sytems that need to be "autobled" and then bled conventionally
Hope this helps.
Dave |
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webby4x4
Forum Admin, Magazine Editor
Rock Star
Posts:2375
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| 03/12/2005 5:18 PM |
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David brings up a good point. You may also need to invest in, or rent, a tool called a "Vacula". This is a vaccum operated brake bleeding system that literally sucks the fluid through the lines, instead of gravity bleeding or pumping-the-brake-pedal bleeding.
Be careful of sucking it dry though... have someone watch the reservoir and continually add fluid as it depletes itself. If it goes dry even for a fraction of a second, you have to start all over again! |
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Rick Webster
Editor, 4X4REVIEW.COM - A Tork Media, Inc. Publication
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'74 FJ40 Land Cruiser
"Measure once, cut twice" |
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