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  1. #1
    Member
    Join Date
    May 2011
    Location
    Twin Cities
    Posts
    13

    Optimax 115 Leak Down Question

    I have a 2004 115 Opti with about 160 hours (I need to get out more...). I had a temperature alarm go off at idle last week when on the lake. Under load, it was fine, alarm only at idle. So, I brought it in to a Merc shop for diagnosis.

    The culprit was the water pump, which they replaced. They indicated the report showed about 60 seconds total at about 160 degrees max, across 9 or so incidents. My wife was out with the boat while I unloaded and parked, and she would turn it off each time and let it sit. It was Memorial Day, so it took a while.

    Mechanic said everything was fine with the motor. He did a leak down test, which showed 8% across all cylinders equally. He didn't note compression, but I checked before bringing it in, and it showed 115psi across all cylinders. All were absolutely identical on the gauge.

    I can't tell if the 8% is good or something to worry about. I've seen some information that suggest 8% is "tired", and other reports that say new factory motors are at or around 10%, or that less than 10% is nothing to worry about.

    Just wondering if anyone can give me some clarity on how to interpret those numbers. Motor starts and runs fine, no power problems that I can tell at idle or WOT.

    Thanks.

  2. Member
    Join Date
    Jun 2013
    Location
    LONGVIEW TEXAS
    Posts
    13,941
    #2
    my opinion 10% or less is just fine ,proceed to enjoy
    .................................................. ...the scariest thing in life is the unknown ...................................