Johnson QD-15 Helicoil in exhaust housing

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  • olcah

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 566
    Topics: 94
    #199102

    Working on a 1954 Johnson 10 HP QD-15. When I took the gearbox off the exhaust housing the bolts were tight and I broke one. Got the stub out today but ruined the 1/4 -20 threads in the exhaust housing. The bad threads are in the hole in lower right of the photo.

    I expect to put in a helicoil but noticed that the coils are carbon steel. I think that would be OK as I will seal the screw with Evinrude gasket sealant and I would run the motor in fresh water.

    Wondered if others have a different opinion on this fix?

    Thank you.

    100_6445


    outboardnut

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 930
    Topics: 419
    #199105

    On a motor I received .
    The previous owners solution was to put a nut and bolt

    DSCN2488


    Mumbles


    Replies: 5764
    Topics: 298
    #199115

    Not sure where you got your inserts from but they can’t be genuine Heli-Coils as Heli-Coils are made of stainless steel and not carbon steel. Being made of stainless, they are perfect for use in this application.

    If you don’t have a proper insert, the hole can be drilled and tapped for the next size larger bolt, which is 5/16 X 18 TPI.


    olcah

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 566
    Topics: 94
    #199122

    Outboardnut and Mumbles, Thank you for the info. I just assumed that if an insert is magnetic, it is not stainless steel. My inserts are from a HeliCoil kit but they are magnetic. Looked it up and found this on the Portland Bolt website so learned something new. 🙂

    “The most common stainless steels, 304 and 316, have an austenitic microstructure and start out life non-magnetic. However as they are manufactured from raw steel to fasteners, they go through several cold forming processes (drawing, roll threading, heading) which changes the microstructure from austenitic to martensitic, thereby making the material more magnetic. The more cold forming, the more its microstructure is changed to martensite, and subsequently the more magnetic the fastener is likely to be.”

    Thanks again.


    Mumbles


    Replies: 5764
    Topics: 298
    #199131

    I’ve learnded something new today!

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