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Bravo III cooling water

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  • Bravo III cooling water

    Since, I had my1997 SeaRay 5.7 with BRAVO III outdrive I had to replace the water tube that goes from the Bell Housing to the Gimbal Housing mounted on the transom 2 times. This made me think of why do we need that water path. Can't we just go through the bottom of the boat with a water line to a strainer then to the pump like on an inboard engine? Is it necessary to have the water go through the outdrive to keep it cool?
    The last change done this week showed that the hole were the hose go through the Gimbal housing is getting bigger as a result of corrosion and age. I will cost a lot of money to replace this housing if I have to. Outdrive has to be removed, engine has to come out and then the Gimbal Housing has to be removed and replaced and hose replaced. It looks like Mercruiser wants to sell the whole Gimbal Housing and Bell housing asembly as 1 unit with the Hydrolic lifters mounted. I just replaced my lifters last year, ouch!!!
    I don't want a water leak or an air leak in the water line as a result of a poor connection so I got to figure the best way to do this.
    Any ideas???


  • #2
    Re: Bravo III cooling water

    I cant think of a reason why this would not work? Drive is cooled by simply being in the water. The upper unit will get hot when on plane for a long time, but so do they all. A drive shower fixes that.
    1988 Four Winns Sundowner 235, 5.7-4V 260HP OMC Cobra

    Comment



    • #3
      Re: Bravo III cooling water

      That's what I think also. It can't be that simple of an answer. All IO's have the water going in from the outdrive for some reason.

      Comment



      • #4
        Re: Bravo III cooling water

        All IO's have the water going in from the outdrive for some reason.
        There's about 75,000 new I/O's sold each year in the US. Let's say you're the CEO of a boat manufacturer building ten thousand I/O boats a year. You have a couple of options for getting water to the engine package your assembly line guy is installing.

        1) Hook the hose that comes already installed on the engine to the fitting on the outdrive as the engine is installed. Total cost: 2 minutes of labor to tighten the hose clamp. Let's say you're paying your guy $20/hour. Total cost to you is about $30/hour after taxes, social security, cheap medical, etc. So the 2 minutes extra it took him to install the hose clamp while installing the engine cost you $0.50/minute or a total of $1.

        2) Install a thru-hull fitting and seacock. Parts cost - $20. Drilling hole through the bottom of the boat - 10 minutes. Installing fitting - 10 minutes. Let's say you have to replace one of your $50,000 boats under warranty every 10 years because one of these thru-hull fittings was improperly installed and sunk the boat. Or someone fogets to open the seacock on one every few years and costs you a $10,000 engine. Either way, that means adding $0.50 per boat to the cost to cover the additional failure modes. Total cost per boat = $20 + 20 minutes at $0.50/minute + $0.50 additional warranty work = $30.50 per boat.

        At 10,000 boats per year, Option 1 costs your company $10,000/year. Option 2 costs your company $305,000/year.

        Option 1 leaves an extra $295,000 in the company every year for your Christmas bonus check. Which one are you going to choose?
        Any opinions expressed above are worth exactly what you paid for them!

        Comment



        • #5
          Re: Bravo III cooling water

          All IO's have the water going in from the outdrive for some reason.
          While 45's reason sounds good, it's not the reason. The reason the water comes from the sterndrive is because Mercruiser can control the water flow and make it part f the design of the total drop in package.
          There is nothing wrong with using a thru hull pickup, it happens all the time.
          I would be wondering why you have had to replace 2 of those tubes, normally. Normally they don't fail. Did they fail due to corrosion? If so, you should be looking at why that happened. Is the transom shield boded to the anti corrosion system on your boat?
          Don S.

          sigpic

          Please, no PM's (Private Messages) regarding boat/engine problems.
          That is what the forums are for.
          Only forum/moderator issues will be answered in PM's.

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          • #6
            Re: Bravo III cooling water

            The reason the water comes from the sterndrive is because Mercruiser can control the water flow and make it part f the design of the total drop in package.
            The sterndrive must have water in it for cooling purposes. Mercruiser could care less about "controlling the water flow", the connection is just there as you say to provide a fast, cheap way to get water to the engine.

            As a mechanical design engineer for over 25 years, I can tell you from experience that if you have a question on why something was done a certain way there's one method that will give you the correct answer 99.99% of the time:

            FOLLOW THE MONEY

            I scanned the pages from the Mercruiser 496 BRAVO GASOLINE ENGINE INSTALLATION MANUAL that deal with installing the water pick-up system.



            Here's the page that deals with using the integral factory pick-up. Notice how it's 2 steps:

            1) Connect hose
            2) Tighten hose clamp



            Here's the pages that you follow if you're doing an alternative pickup. I forgot about all the steps and costs blanking off the factory pickup and cutting the existing outdrive/transom hose in my original estimate above. You can add those costs into the CEO's bonus who uses the factory pickup.







            Any opinions expressed above are worth exactly what you paid for them!

            Comment



            • #7
              Re: Bravo III cooling water

              The boat is a 1997 that I purchased in 2004. The first time out I had the overheating problem that was found out to be the hose from the Gimbel Housing to the Bellow Housing as shown on the Mercruised document above. A new line was put in at that time and no problems until last week (7 years later) when I ran aground in muck and had to take the boat to get it flushed and a new water pump that burned out as a result of no water flow to the pump. On my BravoIII the pump is located seperately and not in the outdrive like a Alpha Drive.
              During service the mechanic said the hose was old and plugged from the muck and a broken tapered insert that collected the muck and made the hose bend to reduce flow and hold more muck.
              That's what made me think of why use that method when a through hull water pick up would be a more simple system to and would require no maintenance other than cleaning the in line water filter(like a simple screen strainer filter) before the pump.
              If I simply cut the hose and capped off the Gimble housing as shown in the Mercruiser Document will that get enough water from moving at idle speed or even going a WOT to cool the outdrive?
              Great answers. Thanks a lot !!!

              Comment



              • #8
                Re: Bravo III cooling water

                Absolutely!!! It will cool just fine. If you ran from Miami to Key West @ near WOT, that could be a problem.

                Auto45, you are all wet with your engineering blah-blah.

                Don S +1

                Comment



                • #9
                  Re: Bravo III cooling water

                  Originally posted by pete104
                  Auto45, you are all wet with your engineering blah-blah.
                  LMAO! Yeah, you're right, those Mercruiser engineers don't know what they're talking about.

                  My guess would be that your technical knowledge falls right in line with your ability to read and write my user name.

                  It's 45Auto, not Auto45.
                  Any opinions expressed above are worth exactly what you paid for them!

                  Comment


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