ABS/Traction Control Valve leaking at exhaust when service brakes applied

Discussion in 'Trucks [ Eighteen Wheelers ]' started by budlud2002, Mar 7, 2021.

  1. budlud2002

    budlud2002 Bobtail Member

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    Mar 7, 2021
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    My ABS/Traction control valve is leaking at the exhaust port when I apply the service brakes on my 2009 Kenworth T800. The valve is located on left frame rail midway of cab. I replaced it in Dec. because it was leaking constantly. (It stopped leaking constantly but to be honest, I couldn't tell you if I had the issue of the leaking when applying the service brakes right after replacement or not.) But a week or so after, I did notice the foot valve was leaking so I had that replaced. Within the last 2 weeks, I noticed the ABS valve that was replaced in Dec. is leaking at the exhaust port only when the service brakes are applied. I suspected the valve failed and replaced it again. The issue did not correct and is still leaking at exhaust port but only when I apply the service brakes.

    Called Bendix, said it has to be a bad valve. Not 100% convinced, and not wanting to have to deal with the PIA return process for a 2nd time, for the heck of it, I replaced the relay valve ahead of this valve and that didn't correct the issue either. Parking brake applied/released has no effect. I've clamped off all chambers one at a time and no change. Chased air hoses, none appear crimped/damaged. Checked fuses, all good.

    This valve wasn't an exact replica of the valve that came off of it. That part number was 300317 and this is supposed to be an updated valve with part number K070951BXW. What are the chances of getting 2 bad new valves? Is it possible to have it hooked up wrong? I pulled the line off the relay valve that goes to the ABS valve and don't get any air movement through it at all. Should there be?

    Really just trying to get this fixed with as little downtime as possible and without having to keep throwing $300 valves at it while hoping to get a good one, especially if there's something I'm missing. I'd greatly appreciate any advice or suggestions. Thank you in advance.
     
    TCLEAVES Thanks this.
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  3. TCLEAVES

    TCLEAVES Bobtail Member

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    Oct 29, 2021
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    COULD YOU TELL ME IF YOU FIGURED THIS OUT??? HAVING THE SAME ISSUE.
     
  4. TCLEAVES

    TCLEAVES Bobtail Member

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    Oct 29, 2021
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    I am finding with more research that is possibly the abs valve? Thats not very specific though. Let me know if you found a solution. I appreciate it.
     
  5. TCLEAVES

    TCLEAVES Bobtail Member

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    Oct 29, 2021
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    If anyone finds this, it was the double check valve mounted onto the traction control valve....
     
  6. Garciaz

    Garciaz Bobtail Member

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    Jun 19, 2022
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    I am having the same issue. I have a 2017 peterbilt 579. I replaced the traction relay valve cause when the brakes were released it would leak air from the bottom of valve. Release brakes now and it still leaking from bottom of new valve. I have checked each service line on the brake chambers and none of them are kicking back air. Any help would be appreciated.
     
  7. Inderjit

    Inderjit Medium Load Member

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    Sep 17, 2017
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    I suspect you have a leaking park brake diaphragm in one of the rear brake chambers.
    Air leaks back through the service side of the chamber and back up through the exhaust on the valve.
    Most likely a broken spring punctured the diaphragm.
     
    Heavyd Thanks this.
  8. Heavyd

    Heavyd Road Train Member

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    6,023
    Feb 4, 2009
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    Yes, brake chamber with a leaking center seal will cause this. Pinch off your service brake hoses to the brake chambers one by one until your leak stops to find your culprit.
     
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