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2017 Wabash air backfeed? Check valve? Pressure Protection Valve?

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Joeziah, Dec 30, 2020.

  1. Dec 30, 2020 #1
    Joeziah

    Joeziah Light Load Member

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    When I set my trailer brakes I get a big blast of air backfeeding into my truck, almost like the trailer's air tanks are emptying out of the red glad hand back into my truck's system.

    It actually causes my trucks brakes to not set if I pop both valves at the same time until most of the air seems to bleed out of the trailer.

    There seems to be a pressure relief valve on the inlet side of the trailer's air tank, I'm wondering if that has gone bad? Is there a 1 way valve somewhere on this thing?

    Also, the button you pull to inflate the sliding tandem bolt release will reset if you don't sit there and hold it until what seems to be the majority of the air is dumped from the system.

    Is it that little valve on the side of the tank that has gone bad? Part # is VS-1128 Pressure Protection Valve

    Would this cause these problems?
     
    Joeziah, Dec 30, 2020
    Joeziah, Dec 30, 2020
    #1
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  3. Dec 30, 2020 #2
    Goodysnap

    Goodysnap Road Train Member

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    The VS pressure protection valve most likely supplies air to your air suspension or another regulated device.

    Air most likely charges the tanks through the main emergency brake valve. You are correct that it should not bleed off the entire tank of air to empty. This one way check valve is most likely not servicable seporately and youll have to replace the whole valve.

    Been a long time for me on trailers, so please school me if Im wrong here.
     
    Goodysnap, Dec 30, 2020
    Goodysnap, Dec 30, 2020
    #2
    black_dog106 and Joeziah Thank this.
  4. Dec 30, 2020 #3
    little cat 500

    little cat 500 Road Train Member

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    last time mine did that it was the tractor protection valve
     
    little cat 500, Dec 30, 2020
    little cat 500, Dec 30, 2020
    #3
    black_dog106 and Joeziah Thank this.
  5. Dec 30, 2020 #4
    Joeziah

    Joeziah Light Load Member

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    VS-1128 valve sits on the supply side of the air tank from the looks of it, seems to be the only valve I can see between the truck supply and the air tanks on the trailer.

    This is the only trailer it does it on, I've pulled 2 others, so not a problem on the truck side I assume.
     
    Joeziah, Dec 30, 2020
    Joeziah, Dec 30, 2020
    #4
  7. Dec 30, 2020 #5
    flood

    flood Road Train Member

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    It's a valve on the trailer... You know the valve that dumps the air in the trailer brakes when you pull the red.(you hear it dump) When it goes bad it will back bleed the air back thru the truck also in the cold the valve can freeze
     
    flood, Dec 30, 2020
    flood, Dec 30, 2020
    #5
    Joeziah Thanks this.
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