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Constant slow leaking gear lube below stern drive.

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    Constant slow leaking gear lube below stern drive.

    Hello everyone,

    I’m a bit new to boating and a few months ago I purchased a Bayliner 175 Bowrider with a 3.0 MerCruiser TKS I4 and Alpha 1 V2 outdrive. Before I changed the impeller and gear lube, I noticed that there was quite a bit of gear lube oil dripping below the sterndrive and even some in the bilge. While it’s not a lot, it adds up and has emptied the reservoir in a few weeks (see pictures). I replaced the impeller, seals, housing, and gear oil but the same issue persists (no other issues otherwise). I’m wondering what might be causing this issue and how it might be fixed? While I don’t have too much experience operating on boats, I do have a lot of general mechanical knowledge. There is also no boat mechanic here for quite a distance and my tow vehicle is not currently accessible. If it’s something I could take on, I’d be eager to fix it.

    Thanks and God Bless


    #2
    It may be possible that the line from the gear lube reservoir to the drive may be leaking.

    If you perform a Pressure/Vacuum leak down test, the gear oil must be drained.
    You will also need to somehow plug off the line to the reservoir.



    Rick E. Gresham, Oregon
    2850 Bounty Sedan Flybridge model
    Twin 280 HP 5.7's w/ Closed Cooling
    Volvo Penta DuoProp Drives
    Kohler 4 CZ Gen Set

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      #3
      The plastic gear lube fitting through the transom assembly has been a known failure point. Based on the pics you’ve posted Id look there.

      https://www.wholesalemarine.com/gear...u=22-861150T02
      Click image for larger version

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      Dave
      Edmonds, WA
      "THE FIX"
      '93 2556
      Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

      The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
      Misc. projects thread
      https://www.baylinerownersclub.org/f...56-gctid789773

      Comment


        #4
        Originally posted by builderdude View Post
        The plastic gear lube fitting through the transom assembly has been a known failure point. Based on the pics you’ve posted Id look there.

        https://www.wholesalemarine.com/gear...u=22-861150T02
        Click image for larger version

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Views:	0
Size:	0
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        I agree with Dave’s suggestion, only explanation for the inner and out leak you described. The external picture is showing a significant leak.
        1997 Maxum 2400 SCR 5.7LX Bravo II

        Mike

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          #5
          Hello,

          I didn’t get around to doing a pressure test, but I suppose I could do one now if necessary. I’ve removed the stern drive unit and immediately noticed a ton of gear lube build up in the bellows. From my understanding, the plastic fitting you guys mentioned is encased by the bell housing. Online I’ve looked and people have said that this phenomenon (oil in bellows) is often caused by a bad yoke seal or something similar (which entails a more complicated procedure). Would a bad yoke seal cause the oil to leak even if the engine isn’t on? And what is the more likely culprit from your understanding? These two are very different procedures.

          thanks and god bless

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            #6
            Here is a picture for reference by the way, although I’m sure you get the idea:

            Comment


              #7
              The plastic fitting potentially failing would not allow gear lube into the u joint bellow. It’s likely a yoke seal failure allowing the lube to enter that area. With that being said the evidence of gear lube at the exterior could be a split in the u joint bellow itself or the plastic fitting is also cracked or something else.
              Dave
              Edmonds, WA
              "THE FIX"
              '93 2556
              Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

              The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
              Misc. projects thread
              https://www.baylinerownersclub.org/f...56-gctid789773

              Comment

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