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Bravoitis/Tubitis, Bypass FIXES ?

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    Bravoitis/Tubitis, Bypass FIXES ?

    OK, looking for some insight. I am evaluating putting in a water pickup bypass to address my Bravoitis/tubitis overheating problem with my 5.0L Bravo III (2012). I boat in all saltwater and have the boat dry rack stored in a barn when not in use. So when I flush/rinse the engines I do so on the hard on a rack. I understand that I’ll either have to cut the hose or cut and plug the original pickups hose in the drive unit when I put a bypass in.

    I want to be able to fresh water flush through the new bypass hose thru a fitting or strainer. Will this allow air to be sucked into the system through the drive when the drive is out of the water and I am fresh water flushing on a rack? If so what is the remedy for this? How is the lower unit cooled with a bypass other than a drive shower?

    My Marina shop has quoted 1k to do a proper fix if no problems exists however they are concerned that corrosion may prevent proper removal of the block off plate causing the need for a new outdrive then the cost may be up to 8k. They are not confident that if corrosion exists that they can successfully remove the screws/bolts and tap new threads for the plate. SO I've gotta make a decision as to which way I go. If you have done this PICS of your fix are a great help!

    Thanks.
    "Relax Inn"
    2012; 255 SB Bayliner
    Venice, Fl
    prior boat:
    2011; 180 BR

    #2
    A through hull seacock and strainer is what most guys have done. A flush T can be added at the seacock. Close the seacock and attach the garden hose for flushing. You could add a fitting to back flush the drive. Some add a drive shower to help cool the leg but cutting the hose between the bell housing and gimbal housing will allow water flow through the drive while running in the water.
    Personally id just repair the Bravoitis issue, but not sure what your access is like.
    Dave
    Edmonds, WA
    "THE FIX"
    '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
    (.030 over-Vortec top end-part closed cooled)
    The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
    Misc. projects thread
    https://www.baylinerownersclub.org/f...56-gctid789773

    Comment


    • FredK
      FredK commented
      Editing a comment
      The Gulf of Mexico Saltwater is brutal on these drives. Most down this way appear to put the bypass in. But talking to my friend (project manager for this) who has done this he came up with the same concern that I would have is we don't cut the pickup hose going thru the transom. The original thought was to leave it alone without cutting and let it work in tandem (AS BEST IT COULD) with the bypass hose. I also evaluating doing the proper repair of the pickup. Thx.

    #3
    FWIW: Bravoitis can often restrict the opening at the gimbal housing down to the point where no water will pass through. In other words, even if you incorporate the original raw water path from the drive into the “new” through hull via a T fitting etc. it may not pull enough through if the Bravoitis condition is not remedied.
    Dave
    Edmonds, WA
    "THE FIX"
    '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
    (.030 over-Vortec top end-part closed cooled)
    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 FredK View Post
      How is the lower unit cooled with a bypass other than a drive shower?

      Thanks.
      the lower unit is always in the water so it doesnt need any cooling, but the upper unit can get pretty hot.... this condition is normal on mercruisers, but not desirable... (the B-III units are worse )... if you putt around most of the time and only bounce up on plane to get back to the dock quickly, nothing needs to done.
      with normal water sport activities you would be ok because you will stop often and the drive has time to cool, but if you are running on plane for extended periods, the upper drive will be out of the water behind the boat and a transom shower will help keep the upper drive a bit cooler for a longer time than without a shower of water spraying over it...


      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


      • Nauti_Mike
        Nauti_Mike commented
        Editing a comment
        Not sure why you think Bravo 3 units would be worse when all Bravo uppers are the same.

      #5
      I don't understand the part about the block off plate? The plate goes on the inside of the transom I just took a couple of pix of mine I hope you can see it. If you could not remove the plastic hose barb that's bolted there stock Click image for larger version

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ID:	536405 . Why couldn't you cut the hose to the raw water pump and put a plug in it? If I did it that way its something I'd want to keep an eye on but it should work. The hose from the bell housing to the outside of the transom is what needs to be cut or removed. That allows water to push up from the pick up screen in the drive and through the drive to cool it while underway.That's the process called out in a couple of the Merc service supplements.
      1992 2452
      5.0 alpha1 gen2

      Comment


      • Nauti_Mike
        Nauti_Mike commented
        Editing a comment
        What lineman said is correct. What is the welded angle for?

      #6
      I knew somebody would catch that. It's the stand to hold my fwc heat exchanger. While I work up a mount for it. What you cant see in the pix is all the cardboard cutouts trying to get the mounting pieces right.
      1992 2452
      5.0 alpha1 gen2

      Comment


      • Lineman1
        Lineman1 commented
        Editing a comment
        I have a thread going on mounting the damn thing I should go back and update it

      • Nauti_Mike
        Nauti_Mike commented
        Editing a comment
        Thought it might be for a HE.
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