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Thread: Lower unit drain hole repair

  1. #1
    Join Date
    Sep 2008
    Bend, Or.

    Default Lower unit drain hole repair

    Thought i'd share my experience with repairing a stripped lower unit drain hole on my 4hp Tohatsu. Ater researching the heck out of it i decided to not go with the heli coil... read that these don't always work out in this application and being that they advice not to use a thread locker i was afraid of the coil coming loose over time and ending up inside the lower unit housing... not to mention having to somehow remove the tag of the heli coil after installation without it dropping into the lower unit. What i went with is the Time-Sert repair kit. This insert has a lip that makes it impossible to drop into the housing, no tag to remove, and can be installed with a thread locker. The installation went great... just make sure the counter bore is deep enough so the insert ends up a hair deeper than the motor housing around the plug hole to get a water tight seal with the plug gasket.
    Last edited by SilverBullets; 04-22-2019 at 02:17 PM.

  2. #2
    Join Date
    Apr 2013
    so jordan ut.


    i'm glad you got it fixed ,i like heli coils my self, because they are stainless steel . but whatever gets it done

  3. #3
    Join Date
    Jan 2009
    Harrisville, Utah


    Over my former lifetime as a mechanic I have used the various methods of repairing of threads. Sometimes just the simple re-tapping of the threads will get you going but as threads become damaged beyond repair the drastic resizing the hole comes to reality. Making sure when drilling out the old hole as straight as possible then running a new tap for your insert is a critical part. I do share the same thought process of the type of application for the comfort of knowing it was done you felt good about. I keep these types of application parts on hand.
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