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post #1 of (permalink) Old 01-22-2004, 03:57 PM Thread Starter
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Broken Bolt in Exhaust Manifold

The shop that I had build me a dual exhaust managed to break a bolt off my manifold where the pipe bolts on. They welded it back to the cast iron and didn't bother to tell me they did it. Obviously, welding to cast iron doesn't work very well. I managed to drill about 1/2" deep into the manifold. I am wondering if JB weld would hold better than the weld or if anyone has another suggestion. I don't know that much about cast iron and what I can or can't do to it.

Any help would be greatly appreciated.
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post #2 of (permalink) Old 01-22-2004, 05:53 PM
 
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Re: Broken Bolt in Exhaust Manifold

Man, that sucks! My first reaction would be to say take it back to them tell them to fix it. But...

a) They were the boneheads that goobered it up in the first place. Odds are decent they could goober something else up in trying to fix it, or worse.
-and-
b) Sounds like you may have destroyed the evidence trying to fix it yourself already.

JB Weld is mighty handy stuff, but I sure wouldn't trust it to hold my exhaust on. And it's not going to do crap against a siezed bolt for trying to get it out (other than make a bigger mess and PITA than you've got already).

You said you drilled about 1/2" into the manifold. Not sure exactly what you mean by this... where precisely did you drill? Through the bolt head? Did the bolt head break off and you drilled in the hole? A pic would help tremendously.
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post #3 of (permalink) Old 01-22-2004, 07:32 PM Thread Starter
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Re: Broken Bolt in Exhaust Manifold

Here is a picture of the broken bolt. The reason I didn't go back to the shop is the fact that I am extremely afraid they would just screw something else up. I drilled about 1/2" deep where the stud was broken off. My original thought was to drill completely through the tab on the manifold, but then thought that may make it to weak. That is when I decided to come to the experts on the board.

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post #4 of (permalink) Old 01-22-2004, 07:53 PM
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Re: Broken Bolt in Exhaust Manifold

I don't think that drilling it thru will hurt. You can always retap it to the next larger size but you should go a little deeper.
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post #5 of (permalink) Old 01-22-2004, 08:27 PM
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Re: Broken Bolt in Exhaust Manifold

1. I had that happen to me..[*]Continue drilling,[*]Using a small drill to drill a pilot hole[*]Then use successively larger drills[*]It will come out fairly quickly[*]But use NEW, or newly sharpened drill bits.
2. Then re-tap as necessary,
3. But, if you don't want to do that,
4. Here's another solution
5. That's crude,
6. But effective.

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post #6 of (permalink) Old 01-22-2004, 08:59 PM
 
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Re: Broken Bolt in Exhaust Manifold

barfnick: I found myself in the exact same situation once upon a busted knuckle... only I was the bonehead that had done the damage in the first place. The heat cylcing those bolts (and the collar) go through is pretty ridiculous, making the bolts themselves very brittle. Having one break is really no suprise, but it still doesn't excuse them "welding" the bolt head on to it to cover it up.

You have a couple choices that I can think of off the bat, depending on how much patience you have...

a) Keep drilling with the same bit (or at least the same size bit) and re-tap the threads. The downside is the bolt material is significantly harder than the cast collar, so your drill bit will have a tendency to try and "slide off" the bolt. Hard to tell from the picture (thanks, by the way - that helps a BUNCH!), but it looks like that may have happened with what you have drilled already. Is what you have drilled so far centered on the bolt hole?

b) You can take a center punch, ding a starting spot in the center of the remaining stud, and start with a very small drill bit. This will go through much easier, then you have a pilot hole. Then use incrementally larger bits to gradually eat out the stud. Eventually, the remaining stud will be thin enough that you can actually just pick it out - probably in pieces.

c) Get some PB Blaster and spray the siezed stud top and bottom. Go have a beer. [img]images/graemlins/40BEER.gif[/img] Make that several. [img]images/graemlins/40BEER.gif[/img] Come back tomorrow morning and spray it again. Place a punch against the remainder of the stud and hit it with a hammer. Spray it once or twice a day and do the mechanical agitation thing (hammer/punch) for at least a couple days. The longer the better. After both you and the sheared stud have soaked for quite some time, drill a pilot hole in the center of the sheared stud. Re-drill it bigger. Get a stud back-out set and see if you can back the stud out. Do not put too much leverage on the back-out wrench (easy to do) or you will shear off the reverse threaded bit in the pilot hole you made (causes a LOT more cussing [img]images/graemlins/cussing.gif[/img] ).

Option "c" will leave you the most material to get a bite on with another stud. Depending on how much material is left from your drilling, you may not even have to drill and tap new threads.

How much material is there left in the collar below what you have drilled? 3/4? 1/2? Keep in mind that with option "b", you will be dependent upon the material that is left in the collar for the new stud threads to get a bit upon. If you have drilled much more than 1/4 of the thickness of the collar, I'd start to have second thoughts about depending on it.

If the hole you have started is not centered, you don't have enough faith in the material left to try option "b", and you don't have the patience/time to do option "c", the keep the drill as straight as you can (harder than it sounds when you're upside down and cussing) and go on through. You'll probably want a carbide bit (at least one). Use low speed and keep the hole oiled if you can. If you're upside down, you'll obviously have to either squirt oil or stop often and dip the bit in oil.

Good luck and keep us posted!
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post #7 of (permalink) Old 01-22-2004, 09:17 PM Thread Starter
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Re: Broken Bolt in Exhaust Manifold

The hole was centered the first pilot hole, but it walked on me. I think I went up in size too much. I will continue to drill with the same size bit and see if I can make it work. It will be slightly off center, but if I can get it tapped, I can round out the hole in the collar to make it fit. If that fails, I will try to drill all the way through and use a nut on the back side, but I would rather not have to try that.

I think the link LEVE sent may be my best option. I am thinking a small C-clamp. [img]images/graemlins/grin.gif[/img]
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post #8 of (permalink) Old 01-23-2004, 12:13 PM
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Re: Broken Bolt in Exhaust Manifold

1 Other way of getting it out is welding a bolt on the other end that sticks out. This way you screw the reamining end through the manifold so it leaves at the other end, if there's enough "flesh" on the other end. The heat of the welding often can loosen the remaining stud a bit so it comes loose. I unscrewed lots of broken bolts and studs that way. (though not all of them....)
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post #9 of (permalink) Old 01-23-2004, 03:19 PM
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Re: Broken Bolt in Exhaust Manifold

If you have not drilled into the manifold (through the side of the stud into the manifold) you can try taking it to a welding shop and see if anyone there can/will take a torch and blow the bolt out for you. Often this can be done without causing any serious damage to the threads (you will have to clean up the threads with a tap).
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post #10 of (permalink) Old 01-23-2004, 04:11 PM
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Re: Broken Bolt in Exhaust Manifold

Ditto on the torch. Takes 5 mintues and is well worth it.
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