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Thread: Impeller Replacement on a Bravo I

  1. #11
    Dr. Eagle
    The housing issue is fixed by buying the whole pump kit. It comes with housing, wear plate, shaft seals, bolts and nuts in addition to the impeller.
    Buy the kit and one of those blue impellers and keep the mercruiser impeller as a spare. It is a good idea to have one.

  2. #12
    XTRM22
    Dr. Eagle:
    The housing issue is fixed by buying the whole pump kit. I never go to the energy of trying to find one of the blue impellars, I change it every year without fail and always carry a spare. My comment to LavyMan was because after doing a ton of work to fix all my water leaks we went out on a one day trip in my boat and the impellar housing was cracked and leaking like a seive! I replace the impellar 1-2 times a season but only replace the housing if it shows signs of wear.
    Chuck wink

  3. #13
    Dr. Eagle
    XTRM22:
    Dr. Eagle:
    The housing issue is fixed by buying the whole pump kit. I never go to the energy of trying to find one of the blue impellars, I change it every year without fail and always carry a spare. My comment to LavyMan was because after doing a ton of work to fix all my water leaks we went out on a one day trip in my boat and the impellar housing was cracked and leaking like a seive! I replace the impellar 1-2 times a season but only replace the housing if it shows signs of wear.
    Chuck wink You are a wise man, I found that you have to replace the impeller every year without fail. If you do not, you risk your engine at the worst and overheating problems caused by debris at the least.
    My philosiphy is just a bit different than yours, I replaced the whole damn thing, seals and all every year. That way you are reasonably sure it is whole. The consequences of not doing so are too great.
    As far as carrying a spare, that is defintely necessary. Me personally, I would not buy one of those blue impellers and use it as an excuse not to do the proper preventative maintenance. I would just keep rebuilding the pump every year. But that is just my $.02...
    [ September 30, 2003, 04:00 PM: Message edited by: Dr. Eagle ]

  4. #14
    HP350SC
    Dr. Eagle:
    OK Laveyman,
    You are smart to do this now, I had to do it on the lake this year because I was too lazy to do it before putting the boat in the water. Best to get the whole repair kit to replace the housing, wear plate and shaft seal, not just the impeller. The kit also comes with new bolts, nuts and washers.
    1. Remove the belt
    2 Remove the hose clamps and hoses on the back of the pump
    3 Remove the pump attachment from the engine.
    4. Disassemble the pump (6 bolts I think) and remove the old impeller.
    5. Discard the old housing.
    6. Insert the inpeller into the new housing and twist the vanes so that they point in the direction they will be running in (important).
    7. Replace the shaft seal "O"ring on the pump mechanism.
    8. Install the new wear plate
    9. Re-assemble the pump
    10. Install the pump on the engine
    11. Hook up the hoses.
    12. Re-install the belt.
    If you have had any of the impeller vanes come off and cannot account for them, pull the hose off of the output side of the oil cooler (the hose that supplies the engine with water) and (before reassembly) flush water through the hose toward the pump. It is a good idea to make sure the impeller chunks are not in the oil cooler or they could end up as obstructions in your water jackets. Am I just reading this wrong?When I replaced my pump I rotated the impeller in the direction it normally turns, as I put the impeller into the housing.Are you saying the vanes should be the other way?

  5. #15
    Dr. Eagle
    The impeller is larger than the diameter of the housing. You have to spin (barely) the impeller while applying pressure pushing it into the housing to it to get it in to the housing. If you get it started in the wrong direction (opposite normal rotation) the impeller vanes have to flip over when you first start the engine and can tear (or so I have been told by the mechanics at the shop). You just want to make sure that the impeller is in its operating position and you are in dandy shape.

  6. #16
    HP350SC
    Thanks for reply-that's the way I did mine.Had me nervous for a second there!

  7. #17
    Dr. Eagle
    HP350SC:
    Thanks for reply-that's the way I did mine.Had me nervous for a second there! Sorry dude! I sometimes am not so clear when I write stuff, especially things that require very precise steps. Didn't mean to make yer heart jump!

  8. #18
    XTRM22
    Hey DrEagle, I have first hand knowledge of pretty near the worst case scenario. One of my buddies never changed the impellar, overheated and blew the head gasket hydrolocking a cylinder. We pulled the plugs and ran hydraulic fluid in each cylinder to protect the cylinders until we could tear it down. I have an 8x10 glossy of the engine, one bank full of water and hydraulic fluid right after we pulled the head. I hung that picture on the wall to remind myself of the consiquences of not changing the impellar. I'm less a wise man and more an educated one.
    Chuck

  9. #19
    TCHB
    This cooling system is as old as the hills and should be replaced with a modern cooling system. How often do you replace your water pump on your car? Does anyone have a set up that last longer than 50 hours?

  10. #20
    Dr. Eagle
    I agree there must be something better. I have seen race pumps, offshore pumps, etc. But they are all the same basic design with perhaps some material improvements, different cases and so on but the same (or similar) neoprene impeller.
    On my OMC King Cobra I would routinely get 200 to 300 hours out of an impeller. I would replace it because so many hours had elapsed, but it didn't even look old. And it was very easy to replace. I don't know why the mercruiser pump is such a common problem.
    On my Eliminator with twin Bravos I got about 60 hours on the first impeller and 95 on the second one season on one and two on the second. But they completely disintegrated and the debris spread into the oil cooler.
    That was the first set, after that I did the pumps as a part of the spring freshen up. I agree...there has to be a better design...

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