Air leak or air dryer?

Discussion in 'Trucks [ Eighteen Wheelers ]' started by mothertrucker004, Jan 18, 2022.

  1. mothertrucker004

    mothertrucker004 Bobtail Member

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    Oct 17, 2021
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    I’ve read just about every thread I can find, but still not sure what to do
    I have a 2007 W9 with a Cummins ISX. 985k miles, out of frame rebuild done at about 750k. I just purchased the truck, and noticed the air purging more often than it should…about every 5-6 min, both driving and parked. I’ve only bobtailed it so far, so no info with a trailer. The governor kicks on at about 105 psi, and blows off at 120 psi…it does this cycle each time. I had my mechanic check for leaks, he found one and fixed it. Am I right thinking there must be another since it is losing air? Or could it be an issue with the air dryer (suggested by those more in the know than I am).
     
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  3. Siinman

    Siinman Road Train Member

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    Did you soak everything down with soapy water? It will tell you pretty fast if you do.
     
  4. mothertrucker004

    mothertrucker004 Bobtail Member

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    Oct 17, 2021
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    No, took it straight from the mechanic to the company I’m leasing on with…in MN, and it’s stupid cold up here. The shop guys are going to look at it for me, but I’d like to have parts on hand for them if I can.
     
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  5. zinita17601

    zinita17601 Road Train Member

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    Check if the heat on the air dryer is working,check for voltage at the plug.
    Since its a new to you truck replace the cartridge anyway,
     
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  6. Heavyd

    Heavyd Road Train Member

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    Install a "T" fitting into the signal line for the unloader to the air compressor. Apply shop air to this. This will pressurize the entire signal line, unloaders in the compressor and air dryer and the line itself to the air tank. Now you can check for leaks.
     
  7. BoxCarKidd

    BoxCarKidd Road Train Member

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    that is a great idea! thanks
     
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  8. kranky1

    kranky1 Road Train Member

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    If you have the same AD/IS dryer that’s on my ‘05 prepare yourself for a never ending purge valve nightmare. Had both audible and inaudible leaks that in the end turned out to be the purge valve. Both AD/9 and AD/IS dryers will drive you nuts with purge valves. That said, I’ve always had dry reservoirs so they may be worth the headache.
     
  9. rollin coal

    rollin coal Road Train Member

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    Yeah I put a brand new, not reman, AD9 on sometime last year and within a couple of months had to replace the purge valve :mad: I guess they don't make them like they used to or maybe they do?
     
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