Now what do I do? Northstar block casting porosity
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Northstar Engines and System Technical Discussion Discussion, Now what do I do? Northstar block casting porosity in Cadillac Engine Technical Discussion; ...
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    83CADMAN's Avatar
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    Now what do I do? Northstar block casting porosity

    I finally got all the holes tapped for STUDS but the last hole developed quite a pit / void about halfway down. Damn it’s a good size pit!
    All the holes had looked real good after drilling through.
    Question:
    Is there anything I can do?
    Does this kill my project?

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    stoveguyy is offline Cadillac Owners Connoisseur
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    Hole "opened" up ? So how did it tap? It has full threads, top to bottom? Or partial threads?

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    83CADMAN's Avatar
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    Re: Eek! Now what do i do?

    The hole tapped sweet as you please all the way to bottom. Its when I looked down the hole did things go difficult. (see photo)1994 Caddy N-star removal 022.jpg

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    Re: Eek! Now what do i do?

    94 Northstar ??? Have you read the sticky thread in Northstar Performance on "Root cause if head gasket failure ................." ? I think AJ's pictures of this fault are still in there.

    You would be NOWHERE near the first to have uncovered yet another Northstar block casting porosity.

    I'll leave it to AJxtcman, Tim Carroll, or Jake Wiebe to call this shot.

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    83CADMAN's Avatar
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    Re: Eek! Now what do i do?

    Quote Originally Posted by Submariner409 View Post
    94 Northstar ??? Have you read the sticky thread in Northstar Performance on "Root cause if head gasket failure ................." ? I think AJ's pictures of this fault are still in there.

    You would be NOWHERE near the first to have uncovered yet another Northstar block casting porosity.

    I'll leave it to AJxtcman, Tim Carroll, or Jake Wiebe to call this shot.
    I'm not claiming that I'm the first one to discover the porosity ov the early N* engines.
    I just want to know if I can fill the hole with something.
    Any sugestions?

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    Ranger's Avatar
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    Re: Now what do I do? Northstar block casting porosity

    Hate to say it, but I think you got yourself a boat anchor.

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    Gonna be a crap shoot if that is going to hold when you torque it down. That much damage and it'll probably not hold, sorry to say it's probably junk.

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    Manic Mechanic is offline Cadillac Owners Fanatic
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    Re: Now what do I do? Northstar block casting porosity

    Is the hole still sealed and air-tight? If so I would fill the void with Devcon, re-drill and tap, then continue on like nothing happened. As in I'd probably have no qualms putting the pedal down when necessary. We don't live in a perfect world. If there's no unseen further voiding behind those visible threads I would have no problem thinking the stud won't pull out with what you've got. The Aluminum Epoxy would just be insurance.

    Vernon

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    Block swap time

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    stoveguyy is offline Cadillac Owners Connoisseur
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    U could torque studs and see if that stud holds? If so, than you may have no issues. The aluminum around the threaded is probably the thickest in block. That's where the load from headbolts is transferred into block. Now, how far is it from thread to water jacket void? Never sectioned a block before

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    Speedygman is offline Cadillac Owners Fanatic
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    Re: Now what do I do? Northstar block casting porosity

    If it was me I would use the modern epoxies, in my case I would use JB WELD. I would first make sure that I can screw the new stud in all the way with my fingers, flush out the hole with lots of brake clean or lacquer thinner then put a coating on the stud or use a small rod to put the epoxy down in the hole or void in the block then screw in the stud and let set for 24 hours and then unscrew the stud and if it doesn't screw back in with your fingers tap it again to clean up the threads. Just saying.

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    Manic Mechanic is offline Cadillac Owners Fanatic
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    Re: Now what do I do? Northstar block casting porosity

    Yep, must be something about Rotary Heads, I've had my share also. JB Weld is a great product but the Devcon is made specifically for Aluminum and filling voids in castings is one of the products specific applications. The expansion ratios have been matched etc.

    http://www.devcon.com/prodfiles/pdfs/fam_tds_107.pdf

    Vernon

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    83CADMAN's Avatar
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    Re: Now what do I do? Northstar block casting porosity

    This is the only open casting void found in any of the holes. The depth of the void in the area of damaged threads is Shallow, nowhere near the cooling jacket and near the top of the oversized threaded portion of the stud. I did do an air pressure test and it proved tight.
    1994 Caddy N-star removal 027.jpg1994 Caddy N-star removal 024.jpg

    Quote Originally Posted by Speedygman View Post
    If it was me I would use the modern epoxies, in my case I would use JB WELD. I would first make sure that I can screw the new stud in all the way with my fingers, flush out the hole with lots of brake clean or lacquer thinner then put a coating on the stud or use a small rod to put the epoxy down in the hole or void in the block then screw in the stud and let set for 24 hours and then unscrew the stud and if it doesn't screw back in with your fingers tap it again to clean up the threads. Just saying.
    I like your idea of aluminum epoxy fill, let set and re-tap.
    Thanks for the optimism.
    98eldo32v likes this.

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    Re: Now what do I do? Northstar block casting porosity

    The studs from CCC are installed, the heads are on and torque to 75ft#. It’s down hill from here now!
    The casting void that opened up in one of the thread bores and the sheared guide pin were the only problems I’ve encountered so far. “Knock on wood”
    The void in the block wasn’t all that big and I think there are enough good 5/8-11 threads to hold the stud. I checked out “Devcon” products and found it rather pricey so I used “JB Weld”, High temp / high strength epoxy. I used a popsicle stick as an applicator to fill the shallow pit then I re-tapped it and presto, no more corrosion promoting air filled void.
    Since I hand reamed/tapped all the holes, the alignment of the studs were dead on. The gasket and heads slipped on effortlessly.
    Thanks Tim for the studs! And to all to offered their optimistic words of advise I also thank.

    P.S. Only time will tell if the little patch fails and I loose the HG seal. Then I might call it a boat anchor. Until then….
    CadillacLuke24 likes this.

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    Re: Now what do I do? Northstar block casting porosity

    Sounds good! I'd think if you followed the directions and got it nice and packed in there, you should be good to go! Can't wait to see the finished product

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