Secondary air tank filling, primary not filling, valve problem?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by shatteredsquare, Feb 1, 2024.

  1. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    That dryer (ADIP?) has pressure protection valves. IIRC, primary should raise to 92 or 93 PSI before sending air to secondary.

    I would R&R the assembly at it's age.
     
  2. JB7

    JB7 Heavy Load Member

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    I'll second what Big Road Skateboard says in post #11 to rebuild or replace the dryer. Re-Connect the supply and governor line but leave the green one disconnected. Run the truck and see if there is air coming out. If not problem is in dryer. If so re-connect and go to the other end of green line at the tank, disconnect and run truck to see if air is coming out. If air is coming out there then I would remove the fitting, you could connect the air line to the removed fitting and see if air comes out with truck running. It does not look like there is a check valve going into the tank, not one like this.
    upload_2024-2-1_14-12-14.png
     
    Last edited: Feb 1, 2024
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  3. shatteredsquare

    shatteredsquare Road Train Member

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    thanks!

    [​IMG]

    yeah i don't think there is a check valve from dryer to primary on this system, unless the dryers have a built in check valve on the output? how else would primary not backfeed.

    idk what the black line is going to primary with a check valve
     
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  4. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Small black? Governor signal.

    Scratch that, i see your pic. That'll be unloader signal from the governor to air compressor
     
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  5. Hammer166

    Hammer166 Crusty Information Officer

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    Aren't the Cascadia the ones with the split wet/primary with the check valve on the internal wall of the tank? Or am I remembering something different? Those you have a fitting on the end of the tank to remove to access the check valve with a long extension & socket.
     
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  6. shatteredsquare

    shatteredsquare Road Train Member

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    governor input on this dryer is grey, and governor pops off like normal when primary was dead empty, secondary at 130ish. wonder where that grey governor signal comes from tho
     
  7. JB7

    JB7 Heavy Load Member

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    May not be your exact dryer but yes they have a check valve at the discharge port.
    upload_2024-2-1_14-43-41.png
     
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  8. shatteredsquare

    shatteredsquare Road Train Member

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    A: the air dryer. the air dryer is the distributor. at least this one is

    [​IMG]

    wet tank and secondary tank input holes from dryer

    [​IMG]

    [​IMG]