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I have a 2001 Yamaha 15 hp four stroke outboard motor that has been blowing oil though the air intake into the carb . As I rev it up it will foul the plugs . What would cause this ?

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Could you provide me the model number of the motor to assit with your query

Posted on Aug 26, 2010

  • Luke Bradford
    Luke Bradford Aug 26, 2010

    do not worry about the model number, i have done some research and it is farily common to most model is called blowby.....a term for combustion gases escaping into crankcase and causing oil to be blown thorugh all vent your case, back through the pcv system into the intake..........bad news...this is only caused by poor sealing of piston compression will require a full engine overhaul..........

    unfortunately with the high revs that an outboard goes through, it is a fairly common issue.......

    one cheat is by putting a thicker grade of oil in, but this would cause a harder to start condition, especially when i dont entirely recommend this.



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