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quick one...vent tube vs fill plug?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 77Jimmy, Jun 24, 2003.

  1. 77Jimmy

    77Jimmy 1/2 ton status

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    Yes, I'm asking yet ANOTHER lamo question...on a 12b rear diff, the fill plug is the recessed square plug correct? What is the purpose of the tube that comes out of the top of the differential? My tube runs up out the top of the diff (on the same side as the fill plug but above the fill plug) and is bolted w/ a small bracket to the frame w/ a plug at the top of the tube.
     
  2. Confedneck

    Confedneck 3/4 ton status

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    vent tube lets pressure out (air)
     
  3. 77Jimmy

    77Jimmy 1/2 ton status

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    Ok, thanks. /forums/images/graemlins/thumb.gif

    I need to check out that plug at the end of the vent tube and see how it works...am curious.
     
  4. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    Just ran longer vent tubes into the engine compartment today. Used a K&N crankcase breather /forums/images/graemlins/thumb.gif

    Shorter tubes can allow water to get in.

    Has anyone noticed gear oil build up in the tubes where it runs along the frame rail from the rear? I wonder how it breathes then....?
    I noticed a bit of fluid from my front where there was a low hanging part of the hose. I will probably check/drain those low points periodically.

    Sorry for the hi-jack /forums/images/graemlins/grin.gif
     
  5. wrathORC

    wrathORC 1/2 ton status

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    It's just a mushroom vent. The best engineered ones out there in my opinion. Aftermarket places make the ones with a bunch of little holes but they're like $6. Other manufacturers use all sorts of weird things including stone filters (like fish tank air bubbler things) and merely a piece of foam on a fitting you plug into the hose.
     
  6. wrathORC

    wrathORC 1/2 ton status

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    Well, you're not supposed to have sagging lines. If you route your rear vent tube up inbetween the inner and outer bed skins then you don't have to run it out front and therefore don't have sags. For the transmission and transfer case you merely route it up along with the speedometer cable and terminate them by the brake booster.
     
  7. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    I'll look at re-routing..... I followed the frame rail and that put a BIG dip in it.

    Thanks for the suggestion /forums/images/graemlins/grin.gif
     

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