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  1. #1

    Default Ok to reinstall lower unit with motor upside down?

    I'm having a hell of a time reinstalling the lower units of both my 2014 Mercury 6hp and 3.5hp both are 4 strokes. I've read alot about having things aligned, etc. I can't seem to get it in the last 2 inches. I've tried maybe 60 times and I thought for sure I'd get lucky at some point. I've spun the prop while it's in gear so I could align the gears up above.

    Anyhow, now I'm thinking of turning the motor upside down and trying it that way. Any advice against that?

  2. #2
    Join Date
    Aug 2018
    Janesville, WI

    Default Re: Ok to reinstall lower unit with motor upside down?

    I've seen others do it, and I did it on my old 1964 Merc 110 9.8hp, but I don't know if it's recommended or not. I'd be curious to know as well. It is still difficult doing it with the motor upside down, but without the added stress on your muscles. I've done mine twice in the last couple of weeks, and both times, I don't know really what I did, but it just suddenly fell into place.

  3. #3
    Join Date
    Aug 2015
    Poulsbo, WA

    Default Re: Ok to reinstall lower unit with motor upside down?

    On a 4-stroke, I'd expect all the oil would run out of the crankcase if you turned the motor upside-down. To minimize that, you'd need to drain all the oil out of the crankcase before up-ending. Other than that, I've done it plenty of times on cranky 2-strokes. Just have a pillow, blanket, or something soft to rest the motor on so it doesn't get all scratched up.


  4. #4
    Join Date
    Dec 2015
    maplevalley WA

    Default Re: Ok to reinstall lower unit with motor upside down?

    Never spin the prop to line up the crankshaft splines pull the plugs and spin the flywheel clockwise only. You can damage the impeller spinning the driveshaft backwards.

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