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  1. #1

    Question adjusting valves on 1986-89 3.0l mercruiser

    i have been replacing the headgasket on a 1986-1989 four winns 160 freedom with a 3.0l mercruiser. i was told i had to adjust the valves before running the engine. only problem is i have no idea how to adjust the valves. i have been reading up on it and some people say zero lash and others to do it on compression stroke. i am an automobile technician so i know some stuff abou tthe engine but i have no idea what zero lash is or how to tell if i am on compression stroke. is tdc when pistion is at the top of head?

  2. #2
    Moderator Don S's Avatar
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    Default Re: adjusting valves on 1986-89 3.0l mercruiser

    Have you considered reading the Mercruiser service manual? It tells how to do it.
    Just head up to the Adults Only sticky at the top of this forum and download the manual. You want #10 for your engine. Might as well get #6 for your drive as well. You may need it too.

    i am an automobile technician so i know some stuff abou tthe engine but i have no idea what zero lash is or how to tell if i am on compression stroke.
    That is basic engine knowledge, even in the automotive industry.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  3. #3
    Rear Admiral JustJason's Avatar
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    Default Re: adjusting valves on 1986-89 3.0l mercruiser

    i am an automobile technician so i know some stuff abou tthe engine but i have no idea what zero lash is or how to tell if i am on compression stroke
    jiffy lube, meineke, pep boys, midas, or goodyear?
    just because you found it that way... doesn't mean it's supposed to be that way.

    Part of diagnostics is spending time figuring out not only what the problem is, but also sorting through what it isn't.

    The older the engine is, the chances of it having more than 1 problem goes up exponentially

    Boating has always been a rich mans hobby. Buying a new boat gets cheaper every year, but the maintenance, the repairs, and the overall cost of ownership of a boat has never gotten any cheaper.

  4. #4
    Moderator Bond-o's Avatar
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    Default Re: adjusting valves on 1986-89 3.0l mercruiser

    Quote Originally Posted by JustJason View Post
    Quote:
    i am an automobile technician so i know some stuff abou tthe engine but i have no idea what zero lash is or how to tell if i am on compression stroke
    ----------------------------------------------------------------------------

    jiffy lube, meineke, pep boys, midas, or goodyear?
    Ayuh,.........
    Any Grease is Better,..... Than No Grease at All.......

  5. #5
    Chief Petty Officer wvmedic's Avatar
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    Default Re: adjusting valves on 1986-89 3.0l mercruiser

    Gavin check out this thread, it will explain zero lash.

    http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/valve-adjustment-2-5-l-357665.html

    Compression stroke is what is says, when rotating the crank assembly with the spark-plug out you should hear compression from that cylinder. You can also place a finger over the spark-plug hole and feel compression.

    TDC = Top Dead Center.

    Jeff.

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