SBT Jetski Engines, Parts & Accessories

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  1. #1
    Joined
    Jan 2007
    From
    Maryland
    Posts
    5

    Default Seadoo 657x oil question

    I built a test stand to run (3) 657x motors I have out of the hull. The test rig has all the components needed to simulate running a 657x on traditional oil injection-start switch,stop switch,solenoid,ignition,oil reservoir,gas,throttle,exhaust and cooling. It works great but after running one of the motors for about a half hour, when I disconnected the crankcase return oil line, about a liter of injection oil came out of the motor at the crankcase return port. Where this oil was contained I do not know. I know the crankcase oil is gravity fed from the reservoir and my test stand is about the same height above the motor (approx 14" drop to the inlet port for the crankcase) but I do not understand how the oil return works to return back to the oil tank. Is positive oil pressure created by the rotary valve gear turning to feed the oil back to the reservoir? Is the excess oil internal in the motor due to a compromised seal somewhere in the bottom end? I hooked up the second of three motors and the oil spillage when disconnecting the oil return seemed more normal, only an ounce or two. Two questions, (1) how does the oil return uphill to the reservoir? and (2) what would cause my issue of a liter of oil flowing out of the motor when disconnecting the return line?
    Thanks!!
    (Bill, your advice on the magneto fix worked great!! The housing for the magneto end is different as well, but fortunately the bolt pattern aligned between the '94 and '95 657's. Swapping the housing, stator and flywheel did the trick..Thanks!)
    Kind regards,
    John

  2. #2
    Joined
    Nov 2003
    From
    Glendora, CA
    Posts
    6,846

    Default Re: Seadoo 657x oil question

    The oil resivour holds about a half quart or so of oil and it is not a pressurized system. It just gravity feeds. It does not need to travel back into the tank. The line that comes from under the exhaust manifold is not full of oil that is being pumped back into the oil tank. Basically, the rotary valve gear just needs to be lubricated. It does not really need to be recycled through the oil tank. That line works more as a vent to release air into the tank so the case resiviour can fill with oil. Don't sweat it.
    Bill O'Neal <br>
    WCM
    <a href="http://www.watercraftmagic.com"

  3. #3
    Joined
    Jan 2007
    From
    Maryland
    Posts
    5

    Default Re: Seadoo 657x oil question

    Again Bill, Thanks!
    You're the best. I won't sweat it because it sounds like more is good as far as the lower end is concerned.
    Still wondering though, what might cause the exhaust system (tuned pipe and muffler) to be nearly filled with injection oil and sludgey stuff?
    Possibly related question - how much is a rebuilt 657x?
    Thanks,
    John

  4. #4
    Joined
    Nov 2003
    From
    Glendora, CA
    Posts
    6,846

    Default Re: Seadoo 657x oil question

    Typically, when the muffler is full of oily liquid that is not the normal black sludge, but much thicker with more oil than water, it is because the last engine tha was used had leaky center seals on the crankshaft that allows oil to seep into the cases from the rotary valve cavity.

    SBT gets about $700.00 for a rebuilt 657 motor exchanged..
    Bill O'Neal <br>
    WCM
    <a href="http://www.watercraftmagic.com"

  5. #5
    Joined
    Jan 2007
    From
    Maryland
    Posts
    5

    Default Re: Seadoo 657x oil question

    That makes perfect sense. Thanks again for all your help, Bill.
    Kind regards,
    John

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