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Maxxforce 13 air compressor where is unloader valve located

Discussion in 'International Forum' started by kubasj05, Feb 9, 2019.

  1. Feb 9, 2019 #1
    kubasj05

    kubasj05 Light Load Member

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    Trying to replace a unloader valve on my air compressor and I'm having trouble figuring out where is unloader valve actually located on this YOO SUNG 7138 compressor. I've changed U-V once or twice on bendix units and they were located in the head but looking at this YOO SUNG 7138 unit does not have anything that would reassemble U-V at that location.
    So, do anyone have an idea of where is located?
    Another question which I'm looking to figure out is actual unloader valve kit. Got one from the dealer and the part # is BXK109119 and this is a Bendix brand that service Bendix BA-921 Compressor. What got me surprised is that this kit looks just like the one I replaced on Detroit series 60 Bendix air compressor past summer. Is it coincidence that both Bendix BA-921 and Yoo Sung 7138 use the same unloader valves or is there something I don't know about.
    Your input is appreciated
     
    kubasj05, Feb 9, 2019
    kubasj05, Feb 9, 2019
    #1
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  3. Feb 9, 2019 #2
    Heavyd

    Heavyd Road Train Member

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    Two different styles of compressors. If you still have the Yoo Sung type, there is no unloader. The air line to it actually disengages a drive clutch to get it to unload. There is also the Bendix style of compressor that has normal type of unloader valves with a normal service kit.
     
    Heavyd, Feb 9, 2019
    Heavyd, Feb 9, 2019
    #2
    kubasj05 Thanks this.
  4. Feb 9, 2019 #3
    kubasj05

    kubasj05 Light Load Member

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    Nevermind, the compressor in fact is a Bendix single piston Ba-921, my fault for confusing both. Valve replaced. Pain in the ### to get to it, lots of time lost on moving stuff out of the way to make just enough room. Be sure to have a bunch of bandaids, patience and knees of steel, if yours are not you're in trouble. Other than that it took 2 hours of my precious life on this otherwise 30 minute job.
    Valve is obviously mounted in the top of the head. Cheers, Jacob
    Yes, you're right Heavyd and thanks for the input. This was a head scratcher in the beginning but I got it figured out, phew.....
     
    Last edited: Feb 9, 2019
    kubasj05, Feb 9, 2019
    kubasj05, Feb 9, 2019
    #3
    Heavyd Thanks this.
  5. Oct 14, 2021 #4
    Wrecker1

    Wrecker1 Bobtail Member

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    Oct 13, 2021
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    Sorry to revive an old thread, but I'm having issues with the actual Yoosung unit. Having hell finding any technical information, and hoping to learn whether replacement is the only option. I've looked into the removal process a bit and would rather have as much info as possible before moving forward. Is there anything that would cause a sudden stop in pressure building?
     
    Wrecker1, Oct 14, 2021
    Wrecker1, Oct 14, 2021
    #4
  7. Oct 14, 2021 #5
    Wrecker1

    Wrecker1 Bobtail Member

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    I have currently only checked the discharge line with my finger for compressor output (will definitely use a gauge next time), changed the governor (replacing 3 T27 socket bits in the process) at the AD-IS dryer, then building a gauging/charge line method to determine whether the issue is with the dryer assembly or the compressor. When the truck was first started, it gave the impression for about 10-15 seconds that it was going to build, went to a little over 10 psi, then stopped and dropped instantly to roughly 5 psi tops. I then charged the system from the same place, between the compressor and dryer, and all air outputs charged fine through the dryer. Is there any output from the dryer besides the governor that could cause the clutch to disengage and stop output from the compressor?
     
    Wrecker1, Oct 14, 2021
    Wrecker1, Oct 14, 2021
    #5
  8. Oct 15, 2021 #6
    Heavyd

    Heavyd Road Train Member

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    Nope.
     
    Heavyd, Oct 15, 2021
    Heavyd, Oct 15, 2021
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  9. Oct 15, 2021 #7
    Wrecker1

    Wrecker1 Bobtail Member

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    Well, then... Guess I'll have to crack open this here retrofit kit and undertake the daunting task before me.
     
    Wrecker1, Oct 15, 2021
    Wrecker1, Oct 15, 2021
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    Heavyd Thanks this.
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