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  1. #1
    Join Date
    Jun 2009
    Location
    From the Needles to the Nab, from Cowes to St Catherine's
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    4,652

    Question Engine raw water pump not priming

    Lift in day yesterday and we had to pour water down the raw water strainer to encourage the water flow to go through the system and come out of the exhaust.

    This happened for the first time last year without any recurrence while the boat was afloat. Never had the problem on previous boats either

    Is this an early sign of future problems or just one of those things that happens from time to time?

    Engine is Yanmar 3YM20 with saildrive. Impeller looked fine and no blockages at the water intake.
    1534

  2. #2
    Join Date
    May 2001
    Location
    UK East Coast
    Posts
    35,486

    Default Re: Engine raw water pump not priming

    Is the lid of the strainer sealing properly?

  3. #3
    Join Date
    Sep 2001
    Location
    Home - Sothampton, Boat - Gosport
    Posts
    9,770

    Default Re: Engine raw water pump not priming

    I had the same problem and it turned out that the intake and engine were fine, but the exhaust elbow water outlets were completely blocked. An overnight soak in brick cleaner and normal service was resumed.
    Steve
    Never believe anything until it has been officially denied.

  4. #4
    Join Date
    Jun 2009
    Location
    From the Needles to the Nab, from Cowes to St Catherine's
    Posts
    4,652

    Default Re: Engine raw water pump not priming

    Quote Originally Posted by pvb View Post
    Is the lid of the strainer sealing properly?
    It looks fine and I did try taking the lid off and reseating it but without success - might try putting some grease round the rubber seal next time around.

    Quote Originally Posted by Stemar View Post
    I had the same problem and it turned out that the intake and engine were fine, but the exhaust elbow water outlets were completely blocked. An overnight soak in brick cleaner and normal service was resumed.
    The engine is only a couple of years old so hopefully that isn't an issue. Nothing noted in the service carried out just before lift out in late February.
    Last edited by Little Grebe; 16-04-19 at 10:49.
    1534

  5. #5
    Join Date
    Jul 2009
    Location
    North Bucks
    Posts
    691

    Default Re: Engine raw water pump not priming

    I've had the same thing in the past on lift-in. It didn't recur during the season so I didn't worry about it.
    Andrew

  6. #6
    Join Date
    Aug 2006
    Location
    NE Coast
    Posts
    1,572

    Default Re: Engine raw water pump not priming

    You do not say IF the pipework after the filter but before the pump was drained or had water in it.

    If it was drained out for winter/ashore etc then when you started up first time you were just sucking air, hence you say once water had been poured down she ran ok.

    Other suspects as others say above,check filter cap rubber may be twisted or worn, check raw water intake pipe between seacock to filter, and discharge elbow
    Archivist for the Colvic Watson Owners Group

  7. #7
    Join Date
    Jun 2009
    Location
    From the Needles to the Nab, from Cowes to St Catherine's
    Posts
    4,652

    Default Re: Engine raw water pump not priming

    The seacock was left open so I would expect most of the water up to the strainer to have drained away when the boat was lifted out.

    However about a stainer full of water escaped from the impeller housing when I look the cover off to check it
    1534

  8. #8
    Join Date
    Feb 2007
    Location
    Essex
    Posts
    21,760

    Default Re: Engine raw water pump not priming

    When this happened to me it was the pump that needed replacing, though it was a lot more than two years old.
    Far away is near at hand in images of elsewhere

  9. #9
    Join Date
    Dec 2002
    Location
    Gloucestershire
    Posts
    5,201

    Default Re: Engine raw water pump not priming

    It has just happened to mine. There was a crack in the suction hose.
    I'd rather be naked
    www.mastaclimba.com

  10. #10
    Join Date
    Nov 2009
    Location
    Home UK Midlands / Boat Croatia
    Posts
    18,609

    Default Re: Engine raw water pump not priming

    Quote Originally Posted by Little Grebe View Post
    Lift in day yesterday and we had to pour water down the raw water strainer to encourage the water flow to go through the system and come out of the exhaust.

    This happened for the first time last year without any recurrence while the boat was afloat. Never had the problem on previous boats either

    Is this an early sign of future problems or just one of those things that happens from time to time?

    Engine is Yanmar 3YM20 with saildrive. Impeller looked fine and no blockages at the water intake.
    My two saildrive 3YM30s are exactly the same after a lift out, although sometimes it is one engine that fails to prime and sometimes the other. It has never been both.

    I'll bet that if you slap plenty of silicone grease on the impeller before you launch, the pump will re-prime without a problem. This is what I do as it saves faffing about with the water jug whilst the travel hoist operator is waiting for me to drive off the straps.

    Richard

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