any suggestions (brake valve air leak)

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by thecubantrucker, Nov 12, 2019.

  1. thecubantrucker

    thecubantrucker Bobtail Member

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    hi guys so 02 freightliner century so my brake valves red/yellow sometimes start to leak air inside and I have to wiggle alot for them to stop now when I press the brakes loud hissing noise comes from trailer connect back there when I break hard it doesnt do it I am not losing air I've pushed both valves in turn off truck dont hear leaks about month ago I had replaced a big valve in back and that had fix another problem that I had but anyway if I pop out trailer valve while leaving tractor push in dont heard the sound it I pop out tractor valve and leave trailer pushed in it will make that loud hissing sound I changed the little rubbers on the trailer connect outside and nothing any suggestions
     
  2. Ridgeline

    Ridgeline Road Train Member

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    Get it replace, this is a serious issue that needs to be replaced.
     
  3. thecubantrucker

    thecubantrucker Bobtail Member

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    well what could be the problem that valve or what
     
  4. starmac

    starmac Road Train Member

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    You bneed to get someone to help you and find where the air is leaking to start with.
    Why are you pushing the brake pedal when the tractor valve is out to start with?
     
  5. thecubantrucker

    thecubantrucker Bobtail Member

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    I explained myself wrong if I leave trailer valve out tractor in not Doing it If I leave tractor out trailer in still does it
     
  6. starmac

    starmac Road Train Member

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    Again, why are you applying the brake pedal with the tractor valve out (truck brakes are set)?
     
  7. thecubantrucker

    thecubantrucker Bobtail Member

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    ok so then what get someone to hit the breaks while I look for leaks
     
    truckdriver31 Thanks this.
  8. starmac

    starmac Road Train Member

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    Probably, I do not think it should leak while you are applying pressure, but don't really know. You should not be applying brake pressure from the pedal while the brakes are set though, it can't do anything anyway, and for all I know the air may have to go somewhere, I don't remember ever trying it.
     
    truckdriver31 Thanks this.
  9. Rideandrepair

    Rideandrepair Road Train Member

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    Sounds like Trailers got a leak somewhere, feeding back through parking valve. That’s normal when Trailers leaking. Chock tires and shut Truck off, Brakes released, listen/ look for leak on trailer,then apply trailer hand brake, check again. Park brake valve, leaking, and stopping when wiggled, usually means it’s going bad, that’s a separate issue, replace it ASAP, it will soon leak non stop. Possibly shutting you down.
     
    JonJon78 and truckdriver31 Thank this.
  10. truckdriver31

    truckdriver31 Road Train Member

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    did you hook blue to red and red to blue. it will make air feed backwards threw trailer brakes back to the dash valves
     
    Rideandrepair Thanks this.
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