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Thread: Fitting low water pick up to outboard engine

  1. #11
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    Sorry Phil, I ment the impeller in your water pump, just a precaution, they do wear out.
    Mike

  2. #12
    phillnjack
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    you wouldnt believe how strict i am with impellors.
    i had a engine back in the 1980's that had done 2 hours on a brand new impellor and the impellor went bad.
    the engine siezed up and was totaly destroyed.
    Every couple of runs i whip the legs off to just make sure the impellor housing is clear of any rubbish and check the blades.
    I dont trust any impellors, new or old.
    On a friends johnson 140 recently i took the leg off, his impellor looked like brand new.
    But on close inspection i noticed the impellor was NOT stuck to the hub !!!!!!!!!
    it was totaly useless and was the cause of no water getting to the powerhead.
    That impellor was brand new...
    pic below of the bad impellor, so anyone reading this make sure you do a proper thorough check on them.
    this looked fine, but the rubber stayed static when the shaft was turning !!!!!!!!!

    Name:  DSCF0416x.jpg
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    this the impellor when taken off the shaft !!!!!!!!
    Notice the rubber had only a tiny touch of glue from new !!! this was OMC original part, not a cheap copy.
    Name:  broken hub impellor 1x.jpg
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    .



    phill
    Last edited by phillnjack; 01-02-2013 at 04:29 PM. Reason: terrible spelling mistakes

  3. #13
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    Been messing with OBs for half a century and never saw that one before!

    Jeff

    PS: One if my inboard guys SWEARS that he ran the same impellers in both engines for eleven years without a problem, and only changed them 'cause he felt it was "time"!

  4. #14
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    I second that Jeff, a water press. gauge is still a cheap insurance and yes the oldess impellor I replaced was 11 years old, the vanes where cracked and bent backward.
    Mike

  5. #15
    phillnjack
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    ive never seen this myself before neither, but have since spoke to a few people who have seen this happen.
    And it seems a lot of jabsco pumps have had this happen as well as volvo penta and mercury.

    Its obviosly poor vulcanising at the factory, and if you notice the hub is smooth not a pimpled or rough surface
    like you would expect it to be.
    The new ones that have a plastic hub seem to be more of a melted rubber into the plastic feel about them.

    Anyway as soon as we changed the impellor the water pressure to the motor was great .

    i told a few people about this on scream and fly and on iboats, people there have had this happen before.
    so its not like its one of a kind.

    apparantly a lot of this happened during the 1990's with many different brands of impellor, maybe there was a
    dramatic change in how the vulcanising was done that caused such things to happen.

    probably something cheap was tried by whoever realy made all the impellors for the different company's. ?



    phill

  6. #16
    phillnjack
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    about how long they normally last is probably due to how many hours you run.
    now in the uk most boats are used in salt water, and its not the nice clear warm stuff you se in florida of california.
    In the uk you could not have an impellor for 11 years unless you kept the engine in the attic and never used it.
    even then it would have a set and be useless. ha ha


    phill

  7. #17
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    [QUOTE=phillnjack;127952]about how long they normally last is probably due to how many hours you run.
    now in the uk most boats are used in salt water, and its not the nice clear warm stuff you se in florida of california.
    In the uk you could not have an impellor for 11 years unless you kept the engine in the attic and never used it.
    even then it would have a set and be useless. ha ha

    I'm very religious on flushing my motor with some stuff called Salt-Away, whether I run in salt or fresh water I always use this tuff. I had a 15 hp Evinrude handed down to me and it was really bad about clogging up but once I started using Salt-Away I really never had problems again. I sound salesman but no really it worked great. I've heard of people flushing there motor with vinegar but have been hesitant on that one. I would assume this stuff may help the rubber seals maybe from cracking up but still is no excuse to use it to not change an impeller....

  8. #18
    phillnjack
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    sharpeye mike
    ive just re-read your statement above about how you run your engine.
    you say its 15 inch midsection on a 21.5 transom and you get plenty of water ???????
    thats 6.5 inches up...you must be using a setback of some sort.
    if you bolt the engine direct to the boat at 6.5 inches up the transom, then on plane you shouldnt get enough
    water up that high to cool the engine, and with the longer sharper bullet it should be riding with bullet above the water.

    i cannot see how your getting anything over the water intakes at all without a setback..



    phill

  9. #19
    Team Member LittleCharger's Avatar
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    Quote Originally Posted by phillnjack View Post
    sharpeye mike
    ive just re-read your statement above about how you run your engine.
    you say its 15 inch midsection on a 21.5 transom and you get plenty of water ???????
    thats 6.5 inches up...you must be using a setback of some sort.
    if you bolt the engine direct to the boat at 6.5 inches up the transom, then on plane you shouldnt get enough
    water up that high to cool the engine, and with the longer sharper bullet it should be riding with bullet above the water.

    i cannot see how your getting anything over the water intakes at all without a setback..

    phill
    The centre of Mike's bullet will still be below the pad at that measurement (i think probably around 2"). You need to consider the additional depth the lower unit adds to your equation, the 15 inches is only the mid section. Perhaps Mike can post a picture of his set up and I think that will makes things a little more clear. The 21.5 inches is measured from the bottom of the pad to the U part of the clamp bracket that traditionally sits on the back of the boat.

  10. #20
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    I ran a 15 inch 3 cyl on a critchfield....22 inch transom..pumped fine ..why...?

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