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  1. #1
    Join Date
    May 2008
    Location
    Monterey, Virginia, USA
    Posts
    3

    Default 140HP 1990 SeaDrive High Speed Overheating

    Will idle all day. When running at high speed for a short while the overheat warning sounds.
    Replaced water pump and housing 2+ years ago. Checked thermostats,gaskets,tested temp switches(ok),checked for leaks/blockage(ok). Should I replace the water pump again or could I have a bad cylinder? One other thing...any idea where I can get a water control valve assembly if bad (part OMC 394407)?

  2. #2
    Join Date
    Feb 2001
    Location
    Central West Florida
    Posts
    14,076

    Default Re: 140HP 1990 SeaDrive High Speed Overheating

    Sounds like that two year old water pump has developed a problem. It's best to drop the lower unit, dismantle and inspect the pump, and go from there.

  3. #3
    Join Date
    Sep 2010
    Location
    ontario
    Posts
    13,652

    Default Re: 140HP 1990 SeaDrive High Speed Overheating

    blown head gaskets will sometimes cause overheat.---------------Salt water operation or fresh water ??

  4. #4
    Join Date
    May 2008
    Location
    Monterey, Virginia, USA
    Posts
    3

    Default Re: 140HP 1990 SeaDrive High Speed Overheating

    Have the lower unit off. Will replace water pump now that it's off. If I get a warm day I will also run a compression check for peace of mind. As always on this site...many thanks to you for your time. I've recieved nothing but professional mechanical advise. Will post when able to let you know the final result if interested.

  5. #5
    Join Date
    Feb 2001
    Location
    Central West Florida
    Posts
    14,076

    Default Re: 140HP 1990 SeaDrive High Speed Overheating

    As Racerone suggested, it would be a good idea to check the compression first.

  6. #6
    Join Date
    Apr 2006
    Location
    , Langkawi, Malaysia
    Posts
    5,750

    Default Re: 140HP 1990 SeaDrive High Speed Overheating

    Test the engine temp on both cylinder banks with an IR gun before tearing anything down.
    It might be as simple as one thermostat opens and the other stays closed, that may give an unbalanced cooling leading to overheat on one side.
    A 2 yrs old pump should normally not fail.
    Check that you have water pressure into the valve on stb side of the engine and pressure evenly out to both thermostat covers at idle.

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