Please note this thread has been inactive for 90 days. For the best results, please start a new thread.
Results 1 to 9 of 9
  1. #1
    Petty Officer 1st Class
    Join Date
    Apr 2006
    Location
    Orlando,Fl
    Posts
    224

    Default 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. #2
    Lieutenant Junior Grade
    Join Date
    Sep 2009
    Location
    Erie, PA
    Posts
    1,131

    Default 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
    1977 Glastron V-184 Crestflite, 165HP Inline Six Mercruiser 1
    1978 Sea Ray SRV-195 Closed Bow, 165HP Inline Six Mercruiser 1, Awaiting Engine Transplant.

  3. #3
    Petty Officer 1st Class
    Join Date
    Apr 2006
    Location
    Orlando,Fl
    Posts
    224

    Default 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.

  4. #4
    Commander 45Auto's Avatar
    Join Date
    May 2002
    Location
    Slidell, LA
    Posts
    2,826

    Default 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!

  5. #5
    Honorary Moderator Emeritus Don S's Avatar
    Join Date
    Aug 2004
    Location
    Western WA.
    Posts
    62,323

    Default 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.


    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.

  6. #6
    Commander 45Auto's Avatar
    Join Date
    May 2002
    Location
    Slidell, LA
    Posts
    2,826

    Default 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!

  7. #7
    Petty Officer 1st Class
    Join Date
    Apr 2006
    Location
    Orlando,Fl
    Posts
    224

    Default 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 !!!

  8. #8
    Lieutenant Junior Grade
    Join Date
    Apr 2011
    Posts
    1,215

    Default 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

  9. #9
    Commander 45Auto's Avatar
    Join Date
    May 2002
    Location
    Slidell, LA
    Posts
    2,826

    Default Re: Bravo III cooling water

    Quote 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!

Similar Threads

  1. 2000 Chaparral 5.7L EFI Bravo III cooling - thermostat housing outlet question
    By kfm in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 3
    Last Post: July 12th, 2011, 09:32 AM
  2. HELP my ECM went out on my 350 MAG MPI Bravo Standard cooling Part # 865840T02
    By Joe Ruiz in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 1
    Last Post: June 24th, 2011, 01:04 AM
  3. 5.0 MPI Bravo Three Cooling Diagram/Engine Zinc??
    By 375matt in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 6
    Last Post: May 23rd, 2009, 06:08 PM
  4. Raw Water Cooling Versus Closed Cooling
    By milkyway in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 5
    Last Post: July 22nd, 2007, 10:49 PM
  5. water cooling blockage? bravo 1 water problem
    By murinsky in forum Mercury & Mariner Outboards
    Replies: 1
    Last Post: May 6th, 2007, 05:45 AM
  1. iboats Forum Directory - Over 100,000 forum posts organized by topic