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  1. #1

    Default rust on spark plugs? 5.7 mercruiser

    i just removed my intake on my 5.7 g.m to do a change over and found all of the intake runners on the left side are showing sings of rust,the right side looks great,so i pulled all of the plugs,right side plugs look good just normal color light brown,left side all had rust color.i just used the boat and it ran great no miss fires,no power loss,no running hot.just wondering if a exhaust manifold or riser could be cracked.i just can't see moisture getting in all of the intake runners from a cracked head or bad head gasket !!

  2. #2
    Moderator Bondo's Avatar
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    Default Re: rust on spark plugs? 5.7 mercruiser

    Ayuh,... Follow the Rust tracks,... It'll lead you to the Leak...
    Any Grease is Better,..... Than No Grease at All.......

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