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Leaky outdrive - mystery!

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    Leaky outdrive - mystery!

    I have a question that I hope you all can help me with. I apparently have a very slow outdrive oil leak. When we leave the marina for a week or two when we. One back the oil is at the bottom of the full container. We fill it up and head out, run it for the afternoon, come back and haven’t used any noticeable amount of oil. I can’t for the life of me wrap my head around that, I would have thought the leak would have exacerbated while running, but it’s not. Does anyone have an idea where I could be losing the oil? I have noticed some oil behind the boat on the water, haven’t pulled it out yet to confirm (we are moored in a slip all summer. Thanks in advance!
    Thousand Islands, NY
    "The Compromise"

    1999 Ciera 2355
    Mercruiser 5.0
    Alpha One Gen II

    #2
    My off the cuff guesses are either the shaft seal just behind the prop is leaking.....sometimes fishing line gets in there and tears it up.

    Or there is a little o ring that seals a passage where the upper and lower half of the outdrive meet that could be leaking.
    Present Boat- 2018 VR5 4.5/200hp Mercruiser
    Last Boat- 1998 Capri 1950CL 3.0 Mercruiser

    Comment


      #3
      I’m hoping that when I pull the boat out in a couple weeks that it will be obvious. It will be sitting in the driveway for a bit while I clean things up and fix other issues that developed over the summer.
      Thousand Islands, NY
      "The Compromise"

      1999 Ciera 2355
      Mercruiser 5.0
      Alpha One Gen II

      Comment


        #4
        If on the trailer with the drive trimmed down for a day or two, you should be able to see a leak of that size.

        Put something under the drive to catch any leaks if you are on concrete/asphalt.
        Present Boat- 2018 VR5 4.5/200hp Mercruiser
        Last Boat- 1998 Capri 1950CL 3.0 Mercruiser

        Comment


          #5
          You definitely have a leak. A pressure/vacuum test will help confirm the source. Sounds like it spits out a little lube when it heats up and when it cools down (after shut down) it pulls what it wants from the reservoir. That scenario is better than it pulling in water but you’ll want to check the drive for water contamination
          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


          • MarbleCitySunchaser
            MarbleCitySunchaser commented
            Editing a comment
            How does the pressure/leak test indicate the source? Is it like a leaky tire, you can tell the source by where the air is escaping?

          • builderdude
            builderdude commented
            Editing a comment
            Yes, soapy water spray around the seals would help identify where the pressure is being lost

          #6
          Ditto checking the drive lube for water intrusion.
          If milky, get it out of there ASAP!

          As for the Pressure/Vacuum tests, these are "leak-down" tests of which involves a time frame.

          Merc drive seals are not necessarily designed to hold against vacuum, so don't be surprised if your vacuum readings are low.
          However, they do hold up well to the pressure testing.

          In order to do a pressure leak-down test, the drive oil must be drained.
          Reason: oil under pressure and against the seal lip actually aids in the seal's ability to hold.
          Drain the oil, and this is removed from the equation.

          When performing the test, rotate the input shaft, the prop shaft and any shift mechanism while the test is being performed.

          See your OEM work shop manual for the acceptable pressure/vacuum levels.

          Keep in mind that the drive should hold at least the minimum acceptable pressure/vacuum for a suggested time frame.
          If not, it's time to re-seal the drive!

          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

          Comment


            #7
            Pull the drive, if all your oil is in the bellows then it's the yoke seal.
            Cheers, Hans
            2007 Carver 41 CMY
            Twin Volvo D6-370
            Montreal, Canada
            Midnight Sun I Photos

            Comment


              #8
              Originally posted by MidnightSun View Post
              Pull the drive, if all your oil is in the bellows then it's the yoke seal.
              no sir, there is definitely no inside the engine bay. Definitely outside.
              Thousand Islands, NY
              "The Compromise"

              1999 Ciera 2355
              Mercruiser 5.0
              Alpha One Gen II

              Comment


                #9
                Originally posted by MarbleCitySunchaser View Post
                Originally posted by Hans
                Pull the drive, if all your oil is in the bellows then it's the yoke seal.
                no sir, there is definitely no inside the engine bay. Definitely outside.
                I believe that Hans was suggesting to pull the stern drive and look within the drive shaft bellows for any signs of oil.
                I don't believe that he was suggesting to look under the engine.

                Nonetheless, you need to perform the pressure/vacuum leak-down test in order to determine where it is leaking.
                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

                Comment


                  #10
                  once enough oil is in the bellows, it will overflow into the engine compartment. If the bellows has a small leak then this could very well be the oil you see on the water. Remember, the drive shaft bellows sits above the water line so a small water leak will not be noticed under normal conditions. Still think it is the yoke seal.
                  Cheers, Hans
                  2007 Carver 41 CMY
                  Twin Volvo D6-370
                  Montreal, Canada
                  Midnight Sun I Photos

                  Comment


                    #11
                    Originally posted by MidnightSun View Post
                    once enough oil is in the bellows, it will overflow into the engine compartment. If the bellows has a small leak then this could very well be the oil you see on the water. Remember, the drive shaft bellows sits above the water line so a small water leak will not be noticed under normal conditions. Still think it is the yoke seal.
                    The u joint bellow will be under water while the boat is at rest. If your referring to the drives elevation while up on plane than I agree, the entire gimbal housing is out of the water while on plane.

                    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


                      #12
                      i didnt read ALL the posts, so I may be doubleing someone elses question and suggestion....

                      do you notice the oil low quite often, or has it happpend only a couple times? is the oil in the drive milky, not the reservior, but in the outdrive itself?......

                      the inside of the outdrive is open to atmospheric pressure via the vent hole in the reservoir, so the water pressure should be wanting IN to the outdrive, rather than the oil wanting out..... BUT, most all the seals are doubled with one facing each way, one to keep the water out, and the other to keep the oil in, but if either one fails, depending on which seal, it can allow the respective fluid to leak past....

                      a lot of times, when changing the outdrive fluid, some air may get trapped in the the outdrive that wont be noticed after filling the drive, and then when the drive is used, the air bubble will work its way to the top of the drive (which can leave the bearings without lube, which then overheats, causing a failure).... the reservoir system helps to eliminate this problem.... a lot of upper gear sets have been fried for this very reason, which is why the reservoir system was developed...

                      BUT, in your case, maybe this happened and the oil in the reservoir went into the drive and displaced the air bubble that finely escaped?..... which is the way its supposed to work... top up the reservoir and try it again to see if it is still losing oil....


                      NU LIBERTE'
                      Salem, OR

                      1989 Bayliner 2556 Convertible
                      5.7 OMC Cobra - 15.5x11 prop
                      N2K equipped throughout..
                      2014 Ram 3500 crew cab, 6.7 Cummins
                      2007 M-3705 SLC weekend warrior, 5th wheel
                      '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
                      Heavy Equipment Repair and Specialty Welding

                      Comment


                        #13
                        Drives need maintenance. At the end of season the drive should be removed to inspect for leaks and gimbal bearing condition which will avoid almost all failures during the season.

                        Oil should be changed annually or bi annually if you do not put on many hours during the season. Drive is preferably stored indoors in a heated space which reduces condensation. As for filling, oil MUST be pumped in from the bottom filler hole until it exits the top full hole OR if you have the filler bottle design you pump oil in until it appears in the bottle.

                        If the oil ever drops so there is none in the bottle, I highly suggest you pull the boat and pump oil in from the bottom fill hole otherwise it will burp forever before all the air gets out.

                        FYI, on the bottle design, the connection from the bottle to the drive happens via a spring loaded ball check on the drive or gimbal, can't remember. There is an o-ring there that must be in place or it will leak slightly resulting in contaminated milky drive oil.

                        On another note, the drive bottle should be removed every 5 years or so and cleaned out as the oil in there tends to get old to the point where it grows fungus and float stops working as it never really gets changed sitting there held in place by the ball check.
                        Cheers, Hans
                        2007 Carver 41 CMY
                        Twin Volvo D6-370
                        Montreal, Canada
                        Midnight Sun I Photos

                        Comment


                          #14
                          Here is another thing we’ve noticed since the outdrive oil has been leaking ... after start up we get some smoke (bluish - oil) ... it smokes for a minute and then dissipates. Is it possible this is some of the drive oil that’s leaking out? Otherwise, engines runs well. No knocking, no odd sounds, no hesitations. All seems odd that these issues all started at the same time.
                          Thousand Islands, NY
                          "The Compromise"

                          1999 Ciera 2355
                          Mercruiser 5.0
                          Alpha One Gen II

                          Comment


                            #15
                            There really is no correlation between engine smoke and drive oil. That being said, the antiquated engines and their system normally smoke a little on start up due to a rich mix whether carb or fuel injected. Nature of the beast.
                            Cheers, Hans
                            2007 Carver 41 CMY
                            Twin Volvo D6-370
                            Montreal, Canada
                            Midnight Sun I Photos

                            Comment

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