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  1. #1
    Member
    Join Date
    Jan 2014
    Location
    Bluffton, SC
    Posts
    350

    Valve on bottom of VST, what is it?

    Engine Serial number 0G981368
    2000 Mercury Promax 225
    Not sure on exact make or pitch of prop, it is a stainless 4 blade with no markings on the barrel, it does have four holes and EOT-14326-R4 marked inside the barrel.
    Maximum RPM is unknown at the time because I haven't learned how to drive the boat at WOT and I'm still setting up engine height. At 60 MPH the chine walk starts and I'm still learning to correct it. The RPM is around 5000 at this point.
    Idle water pressure is 4-5 PSI and at 5000 RPM it is around 18, unknown what it will be at when at full WOT as mentioned above.
    Analog instrumentation installed in the dash.
    No engine mods that I'm aware of, but some things aren't adding up.
    The boat is a 1993 Bullet 20XD that I bought used a few months ago.

    While checking for loose wires under the cowling of my engine this afternoon I found a fuel leak coming from a valve on the bottom of my VST that has been rather crudely plugged off by the previous owner. I have no idea what the valve is for, but I suspect it is a remnant from the oil injection system that has also been removed by a previous owner. Can anyone look at the photos below and advise what I'm dealing with and what a proper way to remedy this would be?




    1993 Bullet 20XD
    2000 Mercury ProMax 225



  2. Member
    Join Date
    May 2014
    Location
    Texas
    Posts
    45
    #2
    That is a check valve that permits oil to enter the VST but prevent gas from entering the oiling system. Best to remove and install a metal plug. Don't remember the thread size right now but should be able to remove and compare to get correct size. Also note if all fuel has not leaked out you will get a bit of fuel when you remove it.

  3. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,945
    #3
    Replace with a 1/16" x 27 NPT Stainless Plug. Rhonda keeps these in stock if you can't find it locally.

    Above info is correct... that was the oil delivery check valve (and you are now premix).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
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