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  1. #1
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    Replaced Head Gasket 1989 Johnson 175GT

    1989 Johnson 175GT J175STLCEB. I recently replaced the head gasket on this motor and now I have a water leak coming out on the back side of one of the head bolt holes on starboard side. In tightened bolts to spec from the manual. Not sure why it would be leaking. I took head cover off and it is not warped. Could this be an issue with the block itself. Any suggestions or recommendations on what to check or how to fix this would be appreciated.

  2. Ohio Fishing Reports Moderator omcforever's Avatar
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    #2
    Did you torque them to 20-22 foot pounds in increments sneaking up on final torque from the center out? Did you lightly coat the new head gaskets with OMC gasket sealing compound? Where all bolts cleaned and bolt holes chased? I also coat bolt threads lightly with 2 cycle oil(just me). Did you re-torque after heat cycle? Insure block and head surfaces are clean/flat. Head gasket # 335361? 175 hp take a different head gasket vs a 150/155 crossflow.
    Last edited by omcforever; 05-13-2019 at 05:23 AM.

    Age and treachery will always overcome youth and skill !!

  3. Ohio Fishing Reports Moderator omcforever's Avatar
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    #3
    Cylinder head bolt or cylinder cover bolt(small 1/4x20 bolts)? If it is these then torque to 60-84 inch pounds the same way and lightly coat with OMC gasket sealing compound as well. Insure bolt threads are clean as well as thread holes in head.
    Last edited by omcforever; 05-13-2019 at 05:11 AM.

    Age and treachery will always overcome youth and skill !!

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    #4
    Quote Originally Posted by omcforever View Post
    Cylinder head bolt or cylinder cover bolt(small 1/4x20 bolts)? If it is these then torque to 60-84 inch pounds the same way and lightly coat with OMC gasket sealing compound as well. Insure bolt threads are clean as well as thread holes in head.
    Hello Art,
    It is the cylinder head bolt that bolts the head onto the block. Had new bolts (cost me a bundle) and tapped and cleaned threads. I torqued them 20-22 ft pounds flowing the sequence in the manual and applied OMC sealant to both sides of gasket.. I did check the head on a glass sheet and it was flat did not check the block though. I believe I had the right gasket, but just in case I have ordered another and will redo the installation making sure the block mis flat as well.Hoping it is just the gasket and not block damage.

    Love the rig you posted recently!

  5. Ohio Fishing Reports Moderator omcforever's Avatar
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    #5
    Thanks,,

    Age and treachery will always overcome youth and skill !!

  6. Sprint Boats Moderator Bassmeister's Avatar
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    #6
    Sometimes it needs to go through a couple heat cycles and then retorque.....can be done on the muffs....let her heat up and shut it down then heat up and shut down let her cool down and then retorque.

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    #7
    Quote Originally Posted by Bassmeister View Post
    Sometimes it needs to go through a couple heat cycles and then retorque.....can be done on the muffs....let her heat up and shut it down then heat up and shut down let her cool down and then retorque.
    I have the new gasket on the way and will follow this suggestion on the heat cycles with the new install. Thanks for the suggestion.

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    #8
    So took the head off tonight and cleaned everything up real well again. Did not notice this before, but it looks like the thread hole in the block looks like it might be a Helicoil. If this is a Helicoil could this have failed and be causing the leak?

  9. SC Club Moderator ChampioNman's Avatar
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    #9
    Apply some teflon tape to the threads of the bolt and see if that cures the leak.

  10. Ohio Fishing Reports Moderator omcforever's Avatar
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    #10
    Also insure heli coil isnt flush with block but a tad below...I have also used non hardening #2 sealer(permatex) on weeping thread holes/threads that extend into the water jackets..

    Age and treachery will always overcome youth and skill !!

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    #11
    Quote Originally Posted by omcforever View Post
    Also insure heli coil isnt flush with block but a tad below...I have also used non hardening #2 sealer(permatex) on weeping thread holes/threads that extend into the water jackets..
    Art,
    Helicoil is below block as that is what gave it away to me that it might be a helicoil. So we are all good on that. I will try the teflon tape idea from Champ and progress to the permatex if that does not work. Just waiting on the new gasket to arrive. Appreciate the help and advise.

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    #12
    We used to coat the threads on the head bolts with OMC gasket sealer, as per the service manual.