Slow Air Build Up With Heavier Loads

Discussion in 'Questions From New Drivers' started by SavageSwat, Sep 30, 2022.

  1. SavageSwat

    SavageSwat Bobtail Member

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    Sep 30, 2022
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    2015 KW T680 isx15

    Question i have no air leaks or anything, but when i carry a light load truck air works as usual. But if i carry a load over 30k when my air get below 90psi it build back up really slow. While driving down the road. If it get down to 75psi takes about 8 minutes to build back over 100 psi. Anyone have this problem? Took my truck to kenworth and since it was no load they said they couldn't duplicate the problem.
     
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  3. baha

    baha Road Train Member

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    Ck for any cracks in the lower part of air bagss that are are showing when it's loaded loaded heavy, and leveling valves leaking?
     
    Last edited: Sep 30, 2022
  4. Dave_in_AZ

    Dave_in_AZ Road Train Member

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    Air bags on suspension, or air bags on cab. Cab typically bleeds fast though.

    Since it does it when you're loaded, I'd go with suspension.

    Do yourself a favor and replace all 4 and the fittings at the same time.

    And as long as you've gone that far, do the two on the cab.
     
  5. Rideandrepair

    Rideandrepair Road Train Member

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    Maybe spray some water on connections, checking for leaks before changing parts. If I had to guess, first place I’d check is the leveling valve on suspension. The arm may be sloppy, and less responsive, maybe even leaking a bit, or sometimes sticking. Try to wiggle the arm, see if it’s loose, and make sure the rod it’s attached to isn’t loose or missing a rubber bushing.
     
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  6. Espressolane

    Espressolane Road Train Member

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    Agree, air bags and leveling valve would be the first things to look at. Both truck and trailer.
     
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  7. lester

    lester Road Train Member

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    Are constantly loosing air and building back up? Like driving down the interstate are you loosing air pressure or is it when you are using your brakes that you loose air pressure?
     
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  8. Magoo1968

    Magoo1968 Road Train Member

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    You’re air should never drop to 90 YOU HAVE a air leak or compressor isn’t pumping.
     
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  9. Ridgeline

    Ridgeline Road Train Member

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    I had a truck that was doing something like this, it turned out to be the leveling valve and the valve to drop the air in the bags. When the load was on the truck, the valve was worn enough where it would bleed the air off. the valve was also leaking which was unusual.
     
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  10. SavageSwat

    SavageSwat Bobtail Member

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    Sep 30, 2022
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    Hello fellas i did some checking and foundvout that my air bag leveling arm was leaking air. If i touch it it would blow air from the bolt coming out. Sad that it was at the Kenworth shop for a month and they couldn't figure that out, smh $900 for nothing. Thanks guy hopefully that will fit it i changed it today $177.
     
    Magoo1968 Thanks this.
  11. SavageSwat

    SavageSwat Bobtail Member

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    Sep 30, 2022
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    Exactly what mine was doing i changed it today, i moved the arm a tiny bit it started blow air from the arm bolt
     
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