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Are breather tubes really necessary on your differentials?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by wsudu, Mar 27, 2001.

  1. wsudu

    wsudu Registered Member

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    On my 83', the inlet on the diff for the breather tube broke off, so I can't slip the tube over it....That tube went to a what looked like a vaccuum canister. What the hell are they good for, can I just get rid of the tube all together? Thanks
     
  2. Wheels

    Wheels 1/2 ton status

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    The piece that broke off, are you refering to the elbow that is on the axle itself? GM 10 bolt? What remains if it broke off at the little flange you should be able to get out. By all means replace it and attch another breather tube to it. It's a srtaight shot into you diff through this tube and water, dirt, mud, etc will take this axle out in time. When running,as the fluid in the diff heats and contracts, this tube allows it to breath (I know, duh!). If it's hot and you hit a water hole if will gasp and suck water straight in. By all means, put another tube on it and dont leave it unplugged or cap it off. Sounds like someone hooked it into the evaporative cannister. There is a small plastic part that has a floating cap on it that usually goes into the other end.
     
  3. Blazer1970

    Blazer1970 1/2 ton status

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    If you eliminate the breather, the axle will "breathe" through the axle shaft seals and the pinion seal. You need the breather.

    Tim

    70 Blazer CST 4X4 350 SM465 NP205
    87 Burb 4X4 350
    01 GMC 2500HD 4X4 Duramax/Allison
     
  4. BlazerGuy

    BlazerGuy 3/4 ton status

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    Yeah, if you cap it off the built-up pressure leads to leaky seals [​IMG]

    Murphy's Laws on Life :
    "It is a mistake to allow any mechanical object to realize you are in a hurry."
     
  5. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Yep, the air in the diff heats up and cools which causes it to expand and contract. The seals are not made to withstand pressure so capping it off (sealing it) is not an option. If you leave it open without the tube and cap, then it will inhale dust, water, mud, bugs, whatever happens to be around. This is not good for bearings and gears. Therefore, you need the vent, you need the tube routed to some location higher than any water level you will be crossing, and you need the cap on top. Some people also run a filter and/or reroute it much higher than the rear frame if doing deep water crossings.

    Bad Dog

    85 K30 CUCV, 350 TBI, TH400, NP205, D60/C14, 4.56
    Coming soon: 4" lift, 40" tires, massive cutting, shorter wb and rear overhang.
     

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