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  1. #1

    Default Engine mount lag bolts not holding after being repaired.

    So I'm pissed. I had a shop fix my engine mount lag bolts by pouring epoxy with hardner into the holes and drilling them out. Well the fix didn't last. After one boat trip they're loose again. I also had the shop install a brand new motor. I'm thinking I'm going to make them pull the engine back out, so I can take the boat to a fiberglass shop and have new pads put in like should have been done in the first place. That's what I was going to do, but the shop was adamant that this repair would work.

  2. #2
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    3,406

    Default Re: Engine mount lag bolts not holding after being repaired.

    Typically, that fix works well for thru bolted holes and for light radial loads ( snap fasteners). Axial (threaded) loads not so much.
    Last edited by sandkicker; 11-19-2019 at 06:41 PM.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

  3. #3

    Default Re: Engine mount lag bolts not holding after being repaired.

    So what should I do? If this fix doesn't work, then they need to pull the engine out so I can go fix it properly at a fiberglass shop, don't you think? Also they need to pull the motor out on their dime.

  4. #4

    Default Re: Engine mount lag bolts not holding after being repaired.

    Maybe you could give them an opportunity to make it right.

  5. #5

    Default Re: Engine mount lag bolts not holding after being repaired.

    I will but if this method they used to fix it doesn't work, then they need do something that does and imo the only fix is to take the engine out again and replace the mount pads themselves.

  6. #6
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    12,129

    Default Re: Engine mount lag bolts not holding after being repaired.

    Unless they had removed more of the bad core material prior, the epoxy fix was not a good choice.

    Quote Originally Posted by Fishmaster23 View Post
    I will but if this method they used to fix it doesn't work, then they need do something that does and imo the only fix is to take the engine out again and replace the mount pads themselves.
    What ever they do, and who ever does this for you, make sure that they only cut open the tops of the engine mount stringer shells (the fiberglass shells), and that they leave as much as possible of the shell walls.
    In other words, they will need to remove only the tops of the stringer shells as to remove the bad wood core from within the stringer shells.


    The tops of the shells will be fiberglass encased with new material afterwards.



    If this is an AQ series drive, they must go through the triangulation alignment process to ensure the proper engine mount height adjustment.
    If this is a gimbal suspension drive system, they must check the engine drive coupler alignment by adjusting the height of the engine mounts.




    .
    Last edited by RicardoMarine; 11-20-2019 at 06:34 AM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  7. #7

    Default Re: Engine mount lag bolts not holding after being repaired.

    Why do you want to only remove the top portion? On my boat the engine mount beds aren't connected to the stringers, more so to the bottom of the hull. Is it just easier to rebuild when you leave the sides in place?

  8. #8
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    12,129

    Default Re: Engine mount lag bolts not holding after being repaired.

    Quote Originally Posted by Fishmaster23 View Post
    Why do you want to only remove the top portion? On my boat the engine mount beds aren't connected to the stringers, more so to the bottom of the hull. Is it just easier to rebuild when you leave the sides in place?

    Stringers and/or engine mount towers are always fiber-glass bonded to the boat's hull.
    We will see individual stringers with a separate engine mount tower (such as what you may have), and will see stringers with engine mount towers incorporated.

    Unless severe water intrusion has occurred, followed by freezing that would have separated the glass, the original stringer shell (that was bonded to the hull) can remain.
    In other words, remove the tops only for access to the bad core material.

    Cut out the top portion ONLY (shown in yellow below)
    Dig out the rotten core material.
    Replace the core material while "chinking" around it with resin wet glass strands.
    Replace the several top layers of glass that will now encase the new core material.

    This will show you a typical smaller single engine boat scenario, but may not show your exact scenario.
    None-the-less, the procedure will be the same or very similar.


    Click image for larger version. 

Name:	Stringer  engine mount support.jpg 
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    .
    Last edited by RicardoMarine; 11-21-2019 at 05:55 AM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  9. #9

    Default Re: Engine mount lag bolts not holding after being repaired.

    Lag bolts are fine for initial install. Time and deterioration of wooden core material makes for a difficult repair. Through bolting may be the best option.

  10. #10

    Default Re: Engine mount lag bolts not holding after being repaired.

    You can't through bolt it unless you drill it all the way through the bottom of the boat.

  11. #11
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    12,129

    Default Re: Engine mount lag bolts not holding after being repaired.

    Quote Originally Posted by Fishmaster23 View Post
    You can't through bolt it unless you drill it all the way through the bottom of the boat.
    I believe that he is suggesting thru-bolting a metal angle piece or a U shaped bracket to the stringers.
    These bolts would run through the stringers horizontally, clamping the brackets to the stringers.

    The engine side mounts would then bolt to the bracket via machine threads.

    It is used in cases where stringer repair is being deferred.
    It will work for a while.... maybe longer.



    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

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