Cracked Block Lock-N-Stitch???
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Cracked Block Lock-N-Stitch???

  1. #1
    AKA OhOneWS6 Last Mohican's Avatar
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    Default Cracked Block Lock-N-Stitch???

    I discovered a crack in the water jacket of my Pontiac. Anyone ever fixed a cracked block with the lock and stitch method??? I think I am going to try it. You can order a kit from the manufacturer for a DIY Repair. http://www.locknstitch.com/

    (Clickable Thumb)


    Pretty good pictorial of a Lock-N-Stitch block repair toward the end of this page.
    Lock-N-Stitch Repair for engines, compressors and other cast iron equipment by Reynolds French
    Last edited by Last Mohican; 02-27-2011 at 07:19 AM.

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    tintingsandiego krusn56's Avatar
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    Dig it....
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    Senior Member DuaneHTP's Avatar
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    On a jet boat, a crack like that may never cause a problem as long as there is no crack to the oiling part of the engine. Put a water bypass kit on the inlet water supply to keep the pressure down to where it should be anyway and the crack will probably rust shut in a short time. But, yes the patch would work.
    Duane HTP

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    Senior Member sandeggo's Avatar
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    Quote Originally Posted by Last Mohican View Post
    I discovered a crack in the water jacket of my Pontiac. Anyone ever fixed a cracked block with the lock and stitch method??? I think I am going to try it. You can order a kit from the manufacturer for a DIY Repair. LOCK-N-STITCH Inc. homepage: Cast iron crack repair, cast iron welding, thread repair inserts

    (Clickable Thumb)


    Pretty good pictorial of a Lock-N-Stitch block repair toward the end of this page.
    Lock-N-Stitch Repair for engines, compressors and other cast iron equipment by Reynolds French
    I would pin it, and I'm a welder. pinning is a proven way to have a leak free repair in castings.

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    I have fixed many cracks with lock and stitch or iron tight plugs. both work good but I agree it might not be a problem.

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    Senior Member Fonz69's Avatar
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    Had a small crack sho up on my 427 in my vette, it would only drip a couple of drops when the motor was hot so we used the same epoxy used to hold valley screens in and the leak has stopped.

    Just a thought if you can not get at the crack to pin or fix any other way then having to pull the motor out.

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    Senior Member jetboatperformance's Avatar
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    Matt Xs 4 ,wouldn't hesitate to try to repair that , "stop" drill it, groove it slightly with a dye grinder, grind and clean the surrounding area back away some and give thought to a product like "Smooth-on metalset" (Milspec epoxy) simple quick and effective Tom

    www.skygeek.com search smoothon metalset

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    AKA OhOneWS6 Last Mohican's Avatar
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    All good suggestions. I think it cracked about 5 years ago. This past year is the first summer I have used the boat. It was a project on hold before last summer. I am pretty sure it was cracked all season last year without causing an issue.

    I have a pressure gauge on the intake and with the log exhaust it never moved. I am switching to headers this winter so I may follow Duane's suggestion and add a pressure relief valve.

    I am going to call about the stitch kit and see what it costs. If it is affordable I may try it just for the experience in the technique. If it is too expensive I'll probably just stop drill it and use an epoxy like JB Weld or Tom's metalset recommendation to repair it.

    Thanks to all for the reassurance that it can be fixed relatively easily. My heart just sank when I first found the crack.

    Tom, Is this the stuff?
    http://www.skygeek.com/a4-6oz.html

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    Por 15 epoxy has a 2 part epoxy thats even machinable very tough stuff, i have used to fix issues where lots of pressure wasnt a problem, and lock and stitch works good too..

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    Senior Member jetboatperformance's Avatar
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    AKA OhOneWS6 Last Mohican's Avatar
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    After lots of research and a few phone calls, I decide to go with the stitching pins. I talked to Gary (the owner) at length about his product and the repair I need to make. I am convinced this is the way I want to go. It is a little pricey. I spent $125 for all the materials needed for the repair. That got me 25 stitching pins, 2 drill bits, tap, tapping fluid and pin sealant. Gary says that will be more than enough pins to repair a crack of this length. If I ever need to make another one of these repairs all I will need is more pins. They are ~$35 per 25. I know this seems like overkill for this repair. I look at it as a chance to learn a new technique and considering what I have already spent on this boat $125 is a drop in the bucket.

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    www.highflowdynamics.com LakesOnly's Avatar
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    Cool

    A colleague of mine was at the Lock-n-Stitch booth at a trade show. As a demo, they did the following:
    • Presented a steel plate (about 2 feet square) with a couple of holes at each end
    • Sawed the plate in half (into two entirely seperate pieces)
    • Stitched the plate together using Lock-n-Stitch Castmasters
    • Then, using an engine hoist with a chain, they picked up an SBC block with the repaired steel plate chained between the hoist and the block.
    Pretty convincing stuff.

    And yes, like JBP stated, proper prep and a high quality two-part epoxy repair can often get the job done in cases such as yours.

    LO
    High Flow Dynamics
    Performance Components for the 429/460 Engine Family


    This post © Copyright 2007-2017 Paul Kane. No copying, linking, printing or otherwise without express written permission.

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    AKA OhOneWS6 Last Mohican's Avatar
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    The package showed up today even though FexEx tracking said next Monday. Everything looks to be very high quality. It was all packaged very well. The fluid bottles have foil seals. The tap says "Made in USA". These are all quality pieces. The product information and instructions are very complete and informative. The how to DVD preps you very well for the process.

    (Clickable thumbs)




    The bits and tap are very sharp and work very well. The process is pretty basic. I started by using a sharpie to mark the crack and the ends of the crack so I could see it easier. Drill a hole starting about the width of one lock past the end of the crack. Tap the hole. Coat the pin with sealant and screw it in until it snaps. Grind the pin down to a little above the surface of the block. Drill the next hole overlapping the previous pin anywhere between 10% and 80%. Tap the hole, apply sealant, screw the next pin in until it snaps, grind it down. Repeat, Repeat, Repeat....

    The only thing that is a little tricky is the pins are longer than the block is thick. This makes it it little harder to drill the holes after the first one. You need to keep the drill straight and cut into the previous pin past the thickness of the block so you can tap the next hole straight and get the next pin in straight. It's not that hard Just takes a little patience.

    I got 4 or 5 pins in tonight and stopped to eat dinner. I'll finish it up tomorrow.









    This is a no brainier. If you can drill and tap a hole you can perform this repair with this method. I am convinced I made the right choice. While other cheaper methods may have worked, I will have 100% confidence that this block when I am done. Not to mention I am supporting an American company with American made products.

    Two Big thumbs up to Lock-N-Stitch.

  16. #14
    AKA OhOneWS6 Last Mohican's Avatar
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    So here is the final on the Lock-N-Stitch repair. I have no doubt this is a permanent repair. I would have total confidence doing this type of repair again. You can bet if I ever need do it again, I will inspect the project completely first. Unfortunately, I discovered another unrelated issue with the block that was a game changer. Apparently the casting I have is know for weak main webs. Mine has a crack through the center main web.





    Basically I finish putting the pins in. Ground them down. Hit it with a zip disk to level it out. Hit it with a needle scaller to texture it. Painted it. If the light hits it just right like in the pics you can see where the repair was done. To the naked eye it is less noticeable. I am confident with a little more care with the grinder and scaller this repair could be completely undetectable once painted.










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