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Broken Manifold Stud

Discussion in 'Early CJ5 and CJ6 Tech' started by ronnie victor, Jan 19, 2020.

  1. Jan 19, 2020
    ronnie victor

    ronnie victor Member

    raleigh, nc
    Joined:
    Jun 29, 2015
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    125
    Aw, nuts, Folks. I just broke the nut off an engine block manifold stud on my 66 cj5 F4. Top center; stud now flush with manifold surface. This mess after preparing plenty with PB blaster and warmed engine. I was hoping to remove manifold to gain access to exhaust valves. What to do now?

    I read the many threads on this dilemma and don't have possibility for many of the suggested remedies. I am not a welder, and I don't see how I can find room to center punch the broken stud and then drill. Maybe if I remove heater there will room. Should I just let it go and live with only four manifold bolts?

    Or can I feasibly drill into broken stud and tap in a smaller bolt if i can make engine compartment room? If so, what kind of hardened drill bit?

    I'm reluctant to try removing remaining bolts.

    Your suggestions for getting out of this mess, please. Thanks
     
  2. Jan 19, 2020
    Paulr26

    Paulr26 New Member

    Shelton, CT
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    Dec 27, 2017
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    26
    Best bet is probably to pull the head where you have room to repair the damage and then reinstall. Trying to do it in place would be ugly at best.
     
  3. Jan 19, 2020
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

    Hills of NH
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    Exhaust manifold bolts to the block, not the head. Why it's called an F-head.
     
  4. Jan 19, 2020
    ronnie victor

    ronnie victor Member

    raleigh, nc
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    Yes, studs in block, not head.
     
  5. Jan 19, 2020
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

    Hills of NH
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    I feel your pain. You could just hope for the best, if it is not actually leaking.

    I have the rearmost stud broken, and the firewall blocks access. When the gasket eventually burnt through, I fabricated a clamp that allowed me to plug the exhaust leak without pulling the engine. So far so good.

    Or, possibly could you use a 90ยบ drill adaptor to get in and drlll out the old stud?

    You don't need a hardened drill for the stud. But you will after you break the tap off in the block. Don't ask...
     
    Last edited: Jan 19, 2020
    ITLKSEZ likes this.
  6. Jan 19, 2020
    fyrmn

    fyrmn Member 2020 Sponsor 2019 Sponsor

    High Desert AZ
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    Apr 29, 2006
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    I had a similar issue. Easy outs did not work. I followed the instructions previously discussed in another thread using a torch set up to blow the red hot material out. I have moderate welding skills, so I am no expert. I picked the remainder of material out with dental picks, then chased it with the correct size bottom tap. For clearance purposes you will probably have to remove the fenders and pull the body back.
    I am happy I tried it, I learned quite a bit!
    Thanks to the folks on this forum!
     
  7. Jan 19, 2020
    tcfeet

    tcfeet Member

    east of west,...
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    May 30, 2009
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    I got lucky when trying to remove some exhaust bolts. The last one was seized and was afraid it would twist off.
    A friend who works for GM gave me some "GM heat valve lube." I soaked it twice a day for 3 days. The third day
    I tried a wrench, and it was almost handy. That stuff works.
     
  8. Jan 20, 2020
    Rick Whitson

    Rick Whitson Detroit Area 2020 Sponsor 2019 Sponsor

    I live South of...
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    If you remove the manifold there might be enough stud to weld a nut on the stud and back the broken stud out. It might help if you heated the nuts on the manifold red before you remove them, that expands them and they may not break. I had the same problem, my block had three broken studs, broken flush with the block. I used left hand drills, start small and make sure you drill exact center of the broken stud, and sometimes it will catch the stud and back the broken stud out. Some times you have to re-tap the last of the threads out. Good Luck
     
  9. Jan 20, 2020
    garage gnome

    garage gnome Rust polisher

    Western MA
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    Weld a 5/16" washer to the stud, then weld a nut to the washer. The block threads are course thread, so it should come right out. I've done this many times and it works great.
     
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  10. Jan 21, 2020
    cj3b

    cj3b New Member

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    Be careful drilling. The top center hole is blind and very shallow. If you drill too deep you will drill through a head bolt hole that's directly behind it.
     
  11. Jan 22, 2020
    wasillashack

    wasillashack Member

    Wasilla, Alaska
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    fyrmn tried a method I have used for almost 50 years, works great, if you have an OA torch, try it. Many are concerned about burning or melting the casting. If you doubt yourself, try it on some scrap parts with broken bolts, cast iron is almost impossible to melt with an OA torch. Good luck!
     
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  12. Jan 22, 2020
    ronnie victor

    ronnie victor Member

    raleigh, nc
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    Jun 29, 2015
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    Thanks for suggestions, Everyone. My plan at the moment is to buy a right angle drill that will accommodate the available working space. Good to know about short center stud requiring careful drilling.

    I'm assuming that I'll be able to find a tap for the coarse threads on block side of the new stud.

    There's no remains of broken stud to weld onto or to torch. Stud flush with manifold surface. (No can weld, anyway)
     
  13. Jan 22, 2020
    tomasinator

    tomasinator Member

    Redmond, WA
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    Aug 26, 2015
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    I assume the broken-off-flush stud is on a vertical surface. Could you use a drop of superglue on the perimeter of nut and glue the nut directly over the stud? Then using a wire-feed welder, weld through the hole in the nut to the stud and fill the nut hole with a weld. Then try and very carefully work the nut back and forth with a wrench. If the weld breaks, you can resume drilling and easy-outing.
     
  14. Jan 22, 2020
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

    Hills of NH
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    Hence Nate's suggestion of a washer... You weld into the center hole of the washer, attaching it to the stud. Then weld a hex nut onto the washer for grabbing with a wrench.

    I had to do about 20 of these on a '34 flathead V8 and sometimes the stud broke more than once. :cry: But in the end I got them all.
     
  15. Jan 23, 2020
    NCRenII

    NCRenII yellow fever

    Far Nor Cal
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    I'd recommend taking jeep to muffler shop and they will do the deed. Option is contact a local heavy equipment mobile mechanic to come to your location. Better do it right than really foul things up
     
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