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Thread: Water Impeller

  1. #1
    Join Date
    Jan 2013
    Location
    Kennesaw, Ga
    Posts
    327

    Default Water Impeller

    I have a 90hp Yamaha and when I start it the water doesn't flow out. It's been sitting for a year and has 36hrs on the motor. Do you think the rubber water impeller has broken apart ?

    Thanks,
    2012 Excursion X23C
    90hp Yamaha 4 stroke
    Duel Axle Trailer ready to go anywhere
    All pulled with Z71 4WD Silveradro
    Maritime Mobile KD4LZL
    Lake Allatoona, NW Ga.
    FSO USCG Auxiliary
    Vietnam 66 / 67

  2. #2
    Join Date
    Feb 2014
    Location
    Boat at Lake of the Ozarks Missouri
    Posts
    634

    Default

    Hi Capt:
    Well first how old is the 90hp. It's most likely a relatively newer motor if it only has 36 total hours.

    So here is what I think. Your motor has been a home this past year for the small spider that takes up
    residence in the "tell-tale" water passage coming from the cylinder head of your motor under the cowl.

    Try this; take a small diameter wire, around 16 gauge or so, with the insulation still on the wire; then start your motor.
    When it is running push the wire in the hole and wiggle it around, up & down, back and forth. Soon the water will
    start flowing out. push it up as far as 10 or 12 inches and pull it out.

    Please post your results back here on PDB. This is a very common situation with a motor that sits even over the
    off season. These little critters just love outboard motors. Don't ask me why - try it.

    I would bet your impeller is probably just fine.
    Last edited by Captain Tony; 08-27-2020 at 05:11 PM. Reason: Added comment
    Captain Tony
    2005 Summit by Triton - 220T Platinum 3Log
    2005 115HP Mercury Optimax - 228 Marine Master Trailer
    St. Louis & Lake of the Ozarks, MO.

  3. #3
    Join Date
    Jan 2013
    Location
    Kennesaw, Ga
    Posts
    327

    Default

    Tony, the motor is a 2012. I connected a hose to the hose connection at the motor head and the water flowed just fine. But connecting to the lower unit at the water intake it won't pull the water. I did find a birds nest inside the motor...lol. I checked the inlet and didn't see a blockage, I'm thinking of removing the inlet plates and see what's in there. Thanks for you reply.
    2012 Excursion X23C
    90hp Yamaha 4 stroke
    Duel Axle Trailer ready to go anywhere
    All pulled with Z71 4WD Silveradro
    Maritime Mobile KD4LZL
    Lake Allatoona, NW Ga.
    FSO USCG Auxiliary
    Vietnam 66 / 67

  4. #4
    Join Date
    Feb 2014
    Location
    Boat at Lake of the Ozarks Missouri
    Posts
    634

    Default

    Well you sound like a guy whose is comfortable working on the motor
    so I'll defer to your expertise. I can however suggest one last measure before
    taking the lower unit off to replace the impeller.

    If you take the top cowl off, see if you spot the tell tale overflow hose that
    goes from the thermostat in the cylinder head. If the hose is easily
    detachable, pull it loose and try compressed air going down from top
    to tell tale outlet.

    If anyone has made a web in there it should get blown out. Worth a try
    and easier than the impeller job - but that may be next. Good Luck.
    Captain Tony
    2005 Summit by Triton - 220T Platinum 3Log
    2005 115HP Mercury Optimax - 228 Marine Master Trailer
    St. Louis & Lake of the Ozarks, MO.

  5. #5
    Join Date
    Jul 2006
    Location
    Raystown Country, PA
    Posts
    2,223

    Default

    Try to get it in a barrel, the muffs don't always let it pick up correctly.

    Make sure some insect has not made a nest in the tell tale tube blocking the flow, I clean them out with weed eater line.

    If it does not get the tell tale after these steps, I would pull the lower unit and change the whole kit on a Yamaha, the housings tend to warp, so I always put everything in on Yammys.
    2006 Forester 19 Fish (new deck and carpet, Pontoonstuff interior, 2019)
    1996 Mercury 50 ELPT4S
    1983 Sea Nymph FM171 Striper (complete rebuild from hull up, 2014)
    1985 Johnson 70 J70ELCO

    Raystown Country, PA

  6. #6
    Join Date
    Jun 2004
    Posts
    6,213

    Default

    Since the engine only has 36 hours on it, I would go ahead and change the impeller anyway. I'm guessing it has not been replaced since it has such low hours. As time goes by, and especially when a motor is not used much, the vanes on the impeller take a curved "set" and it becomes much less effective. It can also become brittle and the possibility of a vane breaking is greater. But like was said, a good swabbing with some trimmer line usually will clean out any mud dobber or spider nests. But if that is the original impeller and is 8 years old, I would definitely replace it. Generally it should be replaced every few years anyway.

    Your impeller should look like the one on the left. Over time, it will look like the one on the right and needs replacing..

    Rick

    St. Louis/Lake of the Ozarks

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