Purging air every 17 seconds.

Discussion in 'Volvo Forum' started by Greamreaper, Feb 17, 2018.

  1. Greamreaper

    Greamreaper Bobtail Member

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    Feb 17, 2018
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    2015 VNL 680, purging air every 17 seconds or so.
    Governer replaced twice, driyer filter changed, water drained from tanks. 5 different mechanics for 3 TA shops could not find the issue. Last reply was something wrong with compressor.
    First governer replacement did stop the purge but air pressure was stable in btw 100-140. After restarting the truck, within 5 miles of driving air was draining and rebuilt to 140 on shoulder.
    Anybody had this issue before?
    Thanks..
     
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  3. Ridgeline

    Ridgeline Road Train Member

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    You have an air leak.
     
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  4. Greamreaper

    Greamreaper Bobtail Member

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    We figured out that much.. The problem is where could it be.
    Does abs leak air without breaking?
     
  5. CoyoteExpress

    CoyoteExpress Medium Load Member

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    Water in the airtanks
    I hope you dont got s i-shift
     
  6. Old Man

    Old Man Road Train Member

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    The line to the governen to the tank that tell it to cycle is leaking, it thinks your air is low and kicks in and in just a few seconds it cycles because the pressure is up
     
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  7. Greamreaper

    Greamreaper Bobtail Member

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    You might be onto something there. Currently cycling in btw 110-120
     
  8. Greamreaper

    Greamreaper Bobtail Member

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    Feb 17, 2018
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    Water has been drained, yes its ishift.
     
  9. loudtom

    loudtom Road Train Member

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    The modulators can leak from the supply side without applying the brakes. They can leak from the valve or delivery side when you push the brakes. It doesn't sound like ABS is the problem you're describing.
     
  10. Greamreaper

    Greamreaper Bobtail Member

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    We do have an air leak on right steer abs when breaks applied. But mech said it isnt the cause.
     
  11. Old Man

    Old Man Road Train Member

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    I pretty sure that is the problem, if it is I would ask Ta for a refund.
    $2 worth of plastic line should fix it.

    The dryer purges when the governer cuts out, nothing in the dryer to make it cycle it self( but it is a Volvo and I never had one)

    The governer cuts out when it hits a set pressure.
    There are only 3 components and a few air lines, this ain't rocket science, but a little much for a ta parts changer
     
    Last edited: Feb 17, 2018
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