7.3 IDI leaking transmission fluid into motor oil

Discussion in '6.9L IH & 7.3L IDI Diesels' started by wrgallant, Jun 18, 2012.

  1. wrgallant

    wrgallant Registered User

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    I have a 94 7.3 idi turbo that leaks transmission fluid into the motor when the transmission cooler is connected. I plugged the transmission ports that feed the cooler and the leaking stopped. My guess is that the cooler is causing some sort of pressure difference that is forcing the fluid into the motor.
     
  2. OLDBULL8

    OLDBULL8 Good Morning Ya'll.

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    There shouldn't be any connection between the engine and transmission. Are you talking about an auxilliary transmission cooler mounted in front of the radiator? You do have an automatic trans, right?
     
  3. Agnem

    Agnem Using the Force! Staff Member Supporting Member

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    Where is this "leaked" transmission fluid showing up? In the motor oil, or the coolant. If in the motor oil, how do you know that this is happening?
     
  4. riotwarrior

    riotwarrior Supporting Member Supporting Member

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    Sounds like a leak in a rad tank cooler to me! Getting trans fluid into the coolant and contaminating the coolant, caused by pressure differential of trans pressure and coolant pressure

    maybe wrong...

    JM2CW
     
  5. trackspeeder

    trackspeeder Stone crusher.

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    X2 Coolers can fail with age. A good radiator shop can fix it.
     
  6. wrgallant

    wrgallant Registered User

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    Transmission fluid is showing up in motor oil - I can tell because motor oil level goes up and trans fluid level goes down.
     
  7. wrgallant

    wrgallant Registered User

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    EO4D transmission - fluid gets into motor using radiator cooler or auxiliary cooler.
     
  8. wrgallant

    wrgallant Registered User

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    I get transmission fluid in the motor oil with an auxiliary cooler with no fluid passing through the radiator.
     
  9. OLDBULL8

    OLDBULL8 Good Morning Ya'll.

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    There is no way for transmission oil to get into the engine crankcase oil, in a normal engine, transmission hooked together.
    Surely, no one would hook the transmission cooler return line into the engine.That would be the only way it could get there.
     
  10. paulw

    paulw paulw

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    you have my attention now iv been working on cars for over 20 years i never heard of that
     
  11. FORDF250HDXLT

    FORDF250HDXLT Moose Season @ OBN Supporting Member

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    this is gunna be good.
    :popcorn
     
  12. wrgallant

    wrgallant Registered User

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    Would an external cooler lower fluid pressure in the transmission? I had the transmission off to replace the flex plate over the winter. Could I have damaged a seal?
     
  13. justinray

    justinray Contributor

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    Could you damage the seal? Yes, but a damaged seal would leak oil out, not tranny fluid in, fluid always goes from a high pressure area to a low pressure area, the crankcase isn't necessarily what I would call a vacuum.
     
  14. justinray

    justinray Contributor

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    && no, the external cooler should have no effect on internal pressures.
     
  15. wrgallant

    wrgallant Registered User

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    Could the cooler cause the transmission fluid pressure to be higher than the crankcase pressure?
     

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