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  1. #1
    My Boats:
    71 Donzi '21 Classic
    Join Date
    Apr 2002
    St. Petersburg, FL

    Question Welding external block cracks ?

    Fellas, what are the pro's and con's of brazing or welding this external water jacket crack? Don't be shy!

    As you can tell from the pic. my buddies '87 OMC 5.0L block didn't fare too well in it's last Wyoming winter. The engine's pulled, we're contemplating brazing the crack and pressure testing. If she passes the pressure test, then well put her back in, that if it's a feasible option. Otherwise, it's a new bare or short block, alot more work and a few more $$$$....

    Lemme know what ya think...
    Attached Images Attached Images

  2. #2
    Registered ragtop409's Avatar
    My Boats:
    1995 Nova Spyder
    Join Date
    Jul 2002
    Maximo FLA

    Unhappy block crack

    never seen it done sucsesfully a 5.0 bare block is relitivly cheep good luck. Charlie

  3. #3
    Bo Knows
    I,ve never admitted to this before but 4 years ago a friend brought his boat over with a crack in the block that looked just like yours and it was also from not winterizing properly. It was an older boat and he said he was going to junk it if I couldn't fix it real cheap. I used a small dremel to grind the rough burrs off the exposed section of metal that popped out and then banged it back into place with a hammer. I then lathered on a generous portion of J-B weld. He's still driving this boat around, happy as a clam !!

    Bo knows , and now everyone else does too !

  4. #4
    Charter Member #232 Charter Member Audiofn's Avatar
    My Boats:
    1979 Formula 302, 99 Formula 353, 81 Donzi 18 2+3 with 454
    Join Date
    Oct 2000
    Carlisle, MA USA
    I am with Bo. Go with the JB weld if he is looking to go cheap. It is worth a try. I would think that getting the block hot enough to weld properly you are likely to either crack it more or cause the block to be redecked and what not.

    Put your best foot forward!

  5. #5
    Registered H2Xmark's Avatar
    My Boats:
    1997 Fountain 35 Lightning
    Join Date
    Apr 2001
    beaumont tx
    welding cast iron is a little tricky, but for a real welder, its not to bad, if the boat is a keeper, replace the block, if not check out your options

  6. #6
    My Boats:
    88 IMP Eleganza
    Join Date
    May 2002
    Warrington, PA
    i recently had this same problem
    the previous owner of my boat didn't winterize it properly and i got stuck with the repercussions
    he had the crack welded and needless to say it cracked again. i pulled the motor and took it to my engine builder and he said don't even bother trying to save this block, its junk. BTW my crack wasn't nearly as bad as your buds.
    good luck


  7. #7
    My Boats:
    95 baja
    Join Date
    Mar 2001
    Rochester, MN
    I am with Bo. It is worth a try, I have a buddy that did this and the boat is still running strong. what are you out for trying besides alittle time.

  8. #8
    Registered Biggus's Avatar
    My Boats:
    02 Cigarette Mystique T/S
    Join Date
    Apr 2001
    Naples, Maine
    I`ve used JB Weld on cracked blocks before and it always worked for me too!

  9. #9
    Charter Member #1171 Charter Member obnoxus's Avatar
    My Boats:
    Join Date
    Feb 2001
    New Lenox , Il
    I have seen the JB weld thing done myself,,,, just be sure to stop drill holes at the ends of the crakes to relieve them.

  10. #10
    My Boats:
    Baja Force 235
    Join Date
    Nov 2000
    Westport, Kentucky
    Better pull the intake and look inside. Drill the ends of the cracks, wire wheel and clean with alcohol (or drink it), weld up what you can and cover with JB Weld. Don't run it hard until the temps come up and stabilize. Seen several JB boats run for years. Probably get by with it if no cracks on the inside. If you go this route verify bilge pump is in working order and carry a topsider oil change and some oil and filter on board. You may want to change the T-stat as well.

    Tim T.

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