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Air Leak Problem

Discussion in 'Freightliner Forum' started by Bob.g, Oct 1, 2016.

  1. Oct 1, 2016 #1
    Bob.g

    Bob.g Light Load Member

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    When my tractor and trailer brakes are applied on my air gauge shows that i have a leak (the psi goes down a bit). When only my truck brakes i have no leak. Im not sure if its a valve or what the problem could be
     
    Bob.g, Oct 1, 2016
    Bob.g, Oct 1, 2016
    #1
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  3. Oct 1, 2016 #2
    062

    062 Road Train Member

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    Sounds like it's on the trailer side. Do you have a hand lever for the trailer brakes? If so,with the tractor brake set,pull the lever down,walk back and find the leak.
     
    062, Oct 1, 2016
    062, Oct 1, 2016
    #2
    Bob.g Thanks this.
  4. Oct 1, 2016 #3
    25(2)+2

    25(2)+2 Trucker Forum STAFF Staff Member

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    the road less travelled
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    If It goes down without the pedal or applying the Johnson bar, it's probably a leak on the supply side or leveling valve on an air ride or even just a worn hose or rusted receiver. Could be a leaky gasket in one of the cans(brake chamber).
     
    25(2)+2, Oct 1, 2016
    25(2)+2, Oct 1, 2016
    #3
    Bob.g Thanks this.
  5. Oct 2, 2016 #4
    Bob.g

    Bob.g Light Load Member

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    I just changed the leveling valve, I thought that was the problem but it turns out it wasn't. It only goes down when I apply the pedal, I'm not sure what to change next
     
    Bob.g, Oct 2, 2016
    Bob.g, Oct 2, 2016
    #4
  7. Oct 2, 2016 #5
    stayinback

    stayinback Road Train Member

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    it should go down a little (If your hauling heavy,and you apply some force you should lose about 5-7 psi)

    But If your Losing more than 10 psi per application of the Foot valve- Check all your Tanks and Valves- AND build up 120 psi Release all your Brakes (red and yellow buttons) put truck in gear and Shut off truck.....

    Chock a wheel and Get your Skinny Butt up under there and Listen for Audibility......

    (Theres ALWAYS an air Leak somewhere) lol
     
    stayinback, Oct 2, 2016
    stayinback, Oct 2, 2016
    #5
  8. Oct 2, 2016 #6
    xsetra

    xsetra Road Train Member

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    While you do what stayinback says. You could also just apply trailer brakes to check for leaks. Easier to hear with truck off.
     
    xsetra, Oct 2, 2016
    xsetra, Oct 2, 2016
    #6
  9. Oct 2, 2016 #7
    Bob.g

    Bob.g Light Load Member

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    Sep 28, 2015
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    This happens when im stopped not driving. When i apply both truck and trailer i have a leak but when i apply just truck no leak
     
    Bob.g, Oct 2, 2016
    Bob.g, Oct 2, 2016
    #7
  10. Oct 2, 2016 #8
    xsetra

    xsetra Road Train Member

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    When you are parked, apply the truck parking brake. Does your air leak down to zero, how much time.
    If you set the trailer brakes, this is when you have the air pressure leak down to zero?
    Disconnect the trailer and see if you have the same problem. IF not, the problem is in your trailer. Most likely with the information you have given.
    Probably the pancake seal in one of your cans.
    You may not see the air leak in gauge while you are driving because compressor is running to charge system.
    Good luck
     
    xsetra, Oct 2, 2016
    xsetra, Oct 2, 2016
    #8
    magoo68 Thanks this.
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