1958 18 HP Johnson powerhead removal

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  • muskokaseaflea


    Replies: 9
    Topics: 4
    #6709

    I need to replace a broken shift leaver on my 1958 Johnson and was told that I needed to remove the power head to access the shift rod connector. How many bolts need to be undone? Do I need to remove the flywheel and carb to do this to lift the power head out?

    Thanks,
    Chris Taylor


    frankr

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 6715
    Topics: 51
    #55842

    Exactly what is broken? If just the shift handle, you do not have to pull the powerhead. But if the shift shaft that goes through the exhaust housing, then you do have to remove the powerhead. Take a deep breath–it isn’t as difficult as you might think.

    To make reassembly easier, remove the shifter interlock bar from one side of the powerhead, and remove the vertical throttle shaft from the other side. Disconnect the hoses.

    There are several screws around the rear, below the pan. There are two hex nuts near the rubber mounts on the sides. There is another hex nut inside, below the carburetor. If I haven’t forgotten anything, the powerhead should now lift off.

    No, you don’t have to remove the flywheel or carburetor.


    chas56x

    US Member - 2 Years
    Replies: 49
    Topics: 6
    #55843

    To remove the power head, you will have to remove 7 bolts/screws and two nuts from the studs on the front of the power head. It is easier to get to those nuts if you first remove the pan sections. You don’t have to remove the flywheel or carburetor to remove the power head. If you are using the 2 line fuel/air system, you will have to remove the fuel and air hoses from the fuel connector. You will also have to disconnect the tower shaft that attaches to the magneto plate advance arm. When removing the shift arm, be careful not to drop any screws or washers as you will have to drop the lower unit to fish them out. This would also be a good time to remove the shift lever from the exhaust tower and clean up the pivot shaft, and apply a nice coat of waterproof grease to the shaft. Now would be a good time to make sure the small spring is present in the small hole on the inside flange of the shift lever. If it is missing or worn down, now would be a good time to replace it with a new one. Before reinstalling the power head, coat the top drive shaft splines with a coat of waterproof grease as well. With the power head removed, it is also a good chance to clean out the water cooling jackets, blow compressed air through the cooling passages and put on a new power head gasket. When dropping the power head in place, it may be necessary to rotate the flywheel to line up the drive shaft splines with the crankshaft splines. You do not need to coat the power head gasket with any sealer. Have fun.


    muskokaseaflea


    Replies: 9
    Topics: 4
    #55844

    Thanks for the quick response guys…I have attached some photos of what I am dealing with…I have no idea why this snapped off……just old?!?


    Attachments:


    frankr

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 6715
    Topics: 51
    #55845

    Yep, handle and shaft. And yep, powerhead has to come off


    Mumbles


    Replies: 5764
    Topics: 298
    #55846

    I find it easier to get at the three nuts, one under the carb and one on each side, by removing the carb. The five screws holding the powerhead are underneath and towards the rear. Removing the front and rear pans makes everything easier to get at to. Your motor will have an exhaust baffle installed to so it will need two of the 304598 base gaskets and the kill switch wires have sleeves on them which can be pulled back exposing the connectors.


    david-bartlett


    Replies: 1204
    Topics: 97
    #55848
    quote muskokaseaflea:

    Thanks for the quick response guys…I have attached some photos of what I am dealing with…I have no idea why this snapped off……just old?!?

    This happens when you lay the motor on that side without proper padding or support.

    I always lay mine on the side opposite the shifter.


    muskokaseaflea


    Replies: 9
    Topics: 4
    #55851

    Yes….I am aware of the issue of laying the motor down on the shift lever. This motor was given to me……you have no idea how it was "MacGyvered" together….so I can imagine that it was used and abused over the years……again…thanks for your input! You guys here are great!!!!

    Chris


    chris-p


    Replies: 2456
    Topics: 153
    #55858

    Chris,

    Have you found a replacement piece? I would be happy to send you one if you still need it. I have a box full of em.

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