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  1. #1
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    Feb 2017
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    Owasso, OK
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    1999 200 hp Efi spark plug problem

    A292A5D8-1454-4221-8AAD-E4C8E654C412.jpegAnyone know what might be causing one of my spark plugs to have a milk colored oil on it? It has been running rough lately. When I accelerate it will not get above an idle even at full throttle. I pulled the plugs and one of them had water/oil mixture on it. My first thought was a cracked head gasket, but I did a compression check and all cylinders ranged from 104 to 110. I would appreciate hearing any ideas you might have. Here is a pic of the plug. The engine is 1999 200hp EFI with Boysen Reeds. Serial # 06897131.
    Last edited by Bassin1206; 08-24-2019 at 10:35 PM.

  2. Member
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    #2
    you getting water in that cyl, pull head first
    .................................................. ...the scariest thing in life is the unknown ...................................

  3. Member
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    Feb 2017
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    Owasso, OK
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    #3

    Do I need new head bolts?

    I pulled the head and it appears to have a small leak in the head gasket so I am hopeful this also resolves my performance issues that I’ve been experiencing. Now that I have pulled the head, should I also replace the head bolts? I’ve read somewhere that you should never reuse head bolts so I wanted to ask for your opinions.

    Also, I’ve not had any signs of issues with the other head, but I’m curious, given that this is a 1999 model should I go ahead and replace the head gasket on the other side while I have everything apart? Or is it better to leave it alone since compression on all cylinders looked good when I originally tested? I don’t want to create work for myself, but wanted to verify before I order parts.

    Any suggestions on other things I should check while I’m at it?

    I appreciate all information.


    Quote Originally Posted by JOE54 View Post
    you getting water in that cyl, pull head first

  4. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #4
    Which cylinder?


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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  5. Member
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    Feb 2017
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    Owasso, OK
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    #5
    Port side bottom cylinder

  6. Member
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    Jun 2013
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    LONGVIEW TEXAS
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    #6
    no suppose to be reused ,known of a lot of fudgers out there , if other side shows no problems should be fine even though a good idea to replace
    .................................................. ...the scariest thing in life is the unknown ...................................