Thread: Lower Unit help

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  1. 10-25-2017, 09:07 PM #1
    Truck_fireman
    Truck_fireman is offline
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    Lower Unit help

    Hey guys I just bought a boat with a 99 EFI 175 and want to change the lower unit oil. I’m having a hard time finding out which drain plug gaskets I need and to what level I fill the lower unit. Thanks for any help.
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  2. BIGFLAT
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    #2 10-26-2017, 02:35 AM
    Any Mercury dealer will have the correct gaskets, and the correct oil. Under the lower unit you'll find a silver plug, and above the cavatation plate ( flat plate above the propeller) is another. the top is the vent. While at the dealer, get your self a pump, kinda like a soap dispenser pump to make the job easier. Do search on how and that should make it simpler.Good luck with your new boat.( might want to find/make a boater friend, it'll save you a bit of greif, ask here for help too)...BF

    (ALWAYS add your motors serial number when needing help, Pro's need that)
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  3. rchavis
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    #3 10-29-2017, 04:13 PM
    You need the blue in color gasket , and don't over fill the lower with oil . Fill to the top hole , then when removing the pump let about 1-2 oz drain before add the bottom plug .

    After bottom plug is install, oil should be just below top vent plug hole .
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