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  1. #1

    Default 2006 mercury 25 HP 4 stroke , making oil, things I've worked on

    I have a 06 mercury 25 HP 4 stroke. Its making oil. Last year 2018 ran perfect. I changed the spark plugs in August. Ran fine. Put it to bed in late September. Normal winterizing.

    2019, went fishing 3 times. Installed a trolling plate. Checked plugs. Plugs seemed loose? Not by hand but by wrench. So I pulled them. Clean and look good. Replaced and went fishing.

    The trolling plate required me to really apply throttle. So after 4 hours of trolling went home. Checked the oil the next day. Pulled the dipstick. Oil overflowing out of the hole. Brown oil.
    Read many articles on "making oil". Replaced oil filter, drained oil , tilted motor for hours to get all out.
    Went fishing, trolling did not use the trolling plate. Got home check oil. Clean perfect oil.
    Went fishing again, used trolling plate 2.5 hours. Then lifted the plate trolled 2 hours normal. Then took a 15 minute ride at full throttle. Ran perfect.

    Ran perfect, always does.
    Get home check oil, Brown again. Oil high on stick.
    1. Stuck rings? Carbon build-up due to loose plugs?
    2. Is the trolling plate effecting the engine as I have to push higher rpm for speed.
    Any idea's? It was a used boat. Had it 3 years runs great. Even with this problem. It runs at 22. Mph a 16 ft lund fury.

  2. #2

    Default Re: 2006 mercury 25 HP 4 stroke , making oil, things I've worked on

    Error, its a 2012

  3. #3
    Join Date
    Mar 2019
    Location
    Ottawa Canada
    Posts
    519

    Default Re: 2006 mercury 25 HP 4 stroke , making oil, things I've worked on

    Possible water intrusion. When you changed the oil. Did you replace the drain plug seal?

  4. #4

    Default Re: 2006 mercury 25 HP 4 stroke , making oil, things I've worked on

    No. Only the oil and filter.

  5. #5
    Join Date
    Mar 2019
    Location
    Ottawa Canada
    Posts
    519

    Default Re: 2006 mercury 25 HP 4 stroke , making oil, things I've worked on

    I would inspect the drain plug seal. As it sits below the water line

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