Treadle Valve Honks When Pressed

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Kbb1991, Oct 25, 2020.

  1. Kbb1991

    Kbb1991 Bobtail Member

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    Sep 15, 2019
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    9400 International, when I press the brakes the foot valve literally honks like a goose, and I can feel a little feed back in the pedal like it vibrates a little intermittently. It doesn’t do it every time and it will stop when pressed harder. Does it sound like a bad valve? It doesn’t seem to be stopping like it should when loaded. The brakes are all in adjustment on the tractor and trailer. Stroke is within limits and I have good linings. What else should I be looking for. My primary and secondary air tanks don’t air up even either. The secondary always goes up to 120 and the primary cuts out at around 105.
     
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  3. blairandgretchen

    blairandgretchen Road Train Member

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    Tanks should air up even - unless pressure sensor is ‘off’ on one.

    Id look at replacing foot valve, but I’m a notorious parts changer.
     
    bzinger Thanks this.
  4. Rideandrepair

    Rideandrepair Road Train Member

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    I’ve had it happen in very cold weather, even on a newer Truck. Usually goes away after while.
     
  5. Kbb1991

    Kbb1991 Bobtail Member

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    Sep 15, 2019
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    I found my tank problem, they are coming up even. Faulty gauges. Both of them. I set my cutout pressure with a mechanical gauge at 125 and the truck gauges are reading 150 and 135. The pressure was cutting out around 95 psi on my mechanical gauge and the truck wouldn’t stop worth a dam. Whoever had it before obviously had a lot of faith in the air gauges because they had governor cut out set to it. It will pin you on the wheel now. At 95 before I adjusted it and realized what was going on I had one good pump of the brakes and that was it. I’ve got to figure this foot valve issue out now. I really think it’s bad. When I apply the brakes it exhaust very rapidly out the foot valve for like 1-3 seconds then will stop.
     
  6. SmallPackage

    SmallPackage Road Train Member

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    Does it have a trailer brake hand valve?
    If it does pull that back at the same time you press the foot valve and see if the foot valve honks or vibrates at you. If it still does it is most likely the threadle if it doesn’t it may be a sticky oneway check valve or the tractor protection valve bleeding psi back.
     
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