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Air Leak

Discussion in 'Questions From New Drivers' started by CrappieJunkie, Jul 1, 2014.

Page 1 of 2
  1. Jul 1, 2014 #1
    CrappieJunkie

    CrappieJunkie Wishin' I was fishin'

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    In a van down by the River.
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    For several weeks I have been battling an air leak. Checked it into shop 4 weeks ago...claimed it was fixed. Week later got two air bags replaced on tractor. Week later wasn't holding air pressure after backing under a trailer. Went to Petro. Fixed some valve on front suspension. Now just got it out of shop again and air leak is still present. Shop says see air leak by looking at gauges but been over every inch and can't find it. Safety says it is dot violation. Shop says only dot violation if air is heard leaking or can't pass break check. I did break check and passes.

    Now you know history here is the situation. I am currently bobtail as I was last night. And several other times as well. I build air pressure up at night before bed to 120 psi. 8 hours later sitting at 60 psi in primary tank and 30 psi in secondary. I have a 2010 Pro Star with 591k miles. I admittedly am a bit nervous driving this since the shop can't find air leak. Am I overreacting or should I be demanding new truck.
     
    CrappieJunkie, Jul 1, 2014
    CrappieJunkie, Jul 1, 2014
    #1
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  3. Jul 1, 2014 #2
    gokiddogo

    gokiddogo Road Train Member

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    Check the air leveling valve yet?
     
    gokiddogo, Jul 1, 2014
    gokiddogo, Jul 1, 2014
    #2
  4. Jul 1, 2014 #3
    CrappieJunkie

    CrappieJunkie Wishin' I was fishin'

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    Yeah that is working fine. Raises suspension like its supposed to. Happening both under trailer or bobtail
     
    CrappieJunkie, Jul 1, 2014
    CrappieJunkie, Jul 1, 2014
    #3
  5. Jul 2, 2014 #4
    wore out

    wore out Numbered Classic

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    If it passes air test per pre trip it's safe. Not everybody has a 30 year old ride that holds air for a week or longer.
     
    wore out, Jul 2, 2014
    wore out, Jul 2, 2014
    #4
    Cetane+ Thanks this.
  7. Jul 2, 2014 #5
    WitchingHour

    WitchingHour Road Train Member

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    Get a spray bottle, fill it with a soap and water solution, and start spraying down the air system... the leveling valve may be working fine, but that doesn't mean it's not leaking air. Spray that down, and try the elbow for the air line above the transmission on the passenger side... those are two traditional weak points in the air system.
     
    WitchingHour, Jul 2, 2014
    WitchingHour, Jul 2, 2014
    #5
  8. Jul 2, 2014 #6
    damutt

    damutt Road Train Member

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    agreed with witchinghour, also spry your cab air bags i had a leak there. would drain my tanks in 6hours
     
    damutt, Jul 2, 2014
    damutt, Jul 2, 2014
    #6
  9. Jul 2, 2014 #7
    double yellow

    double yellow Road Train Member

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    1) You are leaking 1 psi every 5 minutes. The legal limit for a bobtail or straight truck is 10x that -- 2 psi every minute (3 psi/min with brakes on). So yes, it is safe and legal to drive.

    2) I would still get it fixed.


    Shops are not going to spend the time necessary to find small leaks like this, so you are going to have to find it yourself. Spray bottle + soapy water and a lot of time. Spray every fitting and connection looking for air bubbles. If you can't find anything, try again but this time wiggle hoses as you spray. In the year and a half I spent in a prostar, I found small leaks at the cab air bags, the fittings on the back of the air tanks, fittings behind the air filter/against the firewall, and at the trailer air supply valve in the cab (at different times).

    Once you finally find the bugger, it'll feel great to start the truck in the morning with 100psi already in the tanks.
     
    double yellow, Jul 2, 2014
    double yellow, Jul 2, 2014
    #7
  10. Jul 2, 2014 #8
    HotH2o

    HotH2o Road Train Member

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    Dip the truck in soapy water. Watch for bubbles. You're allowed 2 psi per minute loss with a single vehicle (tractor only), 3 psi for a combination of two vehicles.
    5 psi for a combination of three or more vehicles for a static test. For applied leakage test you're allowed 3 psi for single vehicles.
    4 psi for a combination of two vehicles.
    6 psi for a combination of three or more vehicles.
     
    Last edited: Jul 2, 2014
    HotH2o, Jul 2, 2014
    HotH2o, Jul 2, 2014
    #8
    gokiddogo, Cetane+ and Trygg Thank this.
  11. Jul 2, 2014 #9
    Lyle H

    Lyle H Road Train Member

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    What motor? If it's an ISX it could be the turbo control valve. I had the same problem when I had one. The valve is located under the compressor and when it leaks, you can't hear the leak. Cummins calls it their "money maker ".
     
    Lyle H, Jul 2, 2014
    Lyle H, Jul 2, 2014
    #9
  12. Jul 2, 2014 #10
    CrappieJunkie

    CrappieJunkie Wishin' I was fishin'

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    It is cummins
     
    CrappieJunkie, Jul 2, 2014
    CrappieJunkie, Jul 2, 2014
    #10
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