Losing air break pressure while ilding

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Goodguy88, May 30, 2017.

  1. Goodguy88

    Goodguy88 Medium Load Member

    470
    138
    May 8, 2017
    0
    International truck

    If truck sits for 10 15 minutes it loses air pressure to brakes, same thing when idling... Low air warning turns on and it starts dropping

    Although when driving, no problems, air pressure stays at about 130 psi

    Also don't think there's an audible air leak as I can't hear anything but may be wrong

    It is a straight truck

    Any help would be great
     
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  3. boneebone

    boneebone Road Train Member

    2,141
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    Mar 13, 2009
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    Simple answer.

    You have a air leak.

    Now the fun part is trying to chase it down.

    Spray all fitting and air lines with Windex or soapy water and look for bubbles.

    See bubbles, fix leak.
     
  4. Gypsy-soul

    Gypsy-soul Bobtail Member

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    May 29, 2017
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    Listen for when it cycles off again or finishes building pressure and if u here a loud pop or hiss check the slack adjusters for play. I think I remember having a similar problem in same setup before. Could be bent or corroded bleed valve. Best bet is to let it build up pressure. Turn off truck and crawl under it and do like post above said to do.
     
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  5. Goodguy88

    Goodguy88 Medium Load Member

    470
    138
    May 8, 2017
    0
    100 percent it's a leak? Problem is this truck is so loud ...That's probably why I'm not hearing anyhing
     
  6. lilillill

    lilillill Sarcasm... it's not just for breakfast

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    Nov 7, 2007
    Possum Booger, Alabama
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    Air it up to 130 lbs, throw it in gear and shut the truck off with the brakes released and the tires chocked. Probably a brake chamber leaking or a bad purge valve on the dryer.
     
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  7. Gypsy-soul

    Gypsy-soul Bobtail Member

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    May 29, 2017
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    What year and model is this truck? Ant spec'd add ons? 6 wheeler?
     
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  8. Goodguy88

    Goodguy88 Medium Load Member

    470
    138
    May 8, 2017
    0
    It's a international workstar 2011 triaxle
     
  9. Goodguy88

    Goodguy88 Medium Load Member

    470
    138
    May 8, 2017
    0
    Now that you mention it I don't think it ever cuts out air pressure. Will check tonight
     
  10. Goodguy88

    Goodguy88 Medium Load Member

    470
    138
    May 8, 2017
    0
    Probably over 400hp not sure. Will try these methods and see what happena
     
  11. Gypsy-soul

    Gypsy-soul Bobtail Member

    18
    9
    May 29, 2017
    0
    Build up your pressure and turn the truck off. Turn the key to auxiliary and press the brakes once and leave it held down. While u do this keep ur eyes on the air gauge and determine how fast it depletes can sometimes give u and idea if it's a major or small slow leak.
     
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