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Need Help - Broken Bolt

One of the 4-5 bolts that hold the front engine mounting bracket on broke off. See the pictures below. The threads stick out a tiny bt, but probably not far enough to grab onto. What should I do? I don't want to try some half a_$ method and dig myself deeper. The other bolts just cracked and then turned loosly. this one was stiff and didn't feel right. I tried to tighten it and it felt the same way. I knew it was going to break, but based on the significance of it I also knew I needed to fix the situation.

John


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Old 12-31-2003, 12:58 PM
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If it was my car I'd get a good center punch and punch a dimple in the center of the bolt. Then using GOOD titanium drill bits start with a 1/8" bit and drill in to a depth of 1", deeper if you know how far the bolt is in the case. Keep moving up bit sizes until you have the bolt drilled out. My guess is that you will probably be able to remove the remainder of the bolt before you even use a 3/8" drill bit.
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Old 12-31-2003, 01:05 PM
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Two things just off the top of my head--

1. Use a slightly smaller diameter drill to drill it out.

2. It looks like there's enough sticking up that you could cut a slot in with a Dremel, pb blast it, and try to back it out with a screwdriver.
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Old 12-31-2003, 01:07 PM
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Hmmm. Must be Dilavar. :-)

You can also try a series of left-hand drills right smack through the middle. The "lefty-loosey" rotation might back out the broken bolt.

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Old 12-31-2003, 01:20 PM
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Sherwood I was going to mention the left-hand drill bits, but I have never found a set worth a crap! Might be worth trying once you got a pilot hole drilled with a regular bit.
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Old 12-31-2003, 01:22 PM
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I would drill it out. The worst that could happen is you end up putting in a helicoil. That is not too bad.
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Old 12-31-2003, 01:37 PM
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if it broke off, you won't get it out with a reverse bit, or easyouts. you will have to drill it dead center, and remove the majority of the shank, in hopes it collapses a tiny bit and releases it's grip. then have a try with a thick easy out, and a bit of heat. if that doesn't get it, use the drill bit from a 10mm timesert kit, which will remove it completely, considering that you were good at centering the pilot drill hole. then do the timesert procedure. get it right the first time, or you're in trouble.
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Old 12-31-2003, 01:58 PM
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ok seince no one mentioned this -propane torch works real G_O_O_D
heat it up spray your favorit collor wrench on it ,do this several times -do the drill thing while cooling dwn (left hand) start small and on center.
after you come up several sizes the so called ez out will take it out- if that dont work weld a stud in the drilled hole and weld a nut on that! it will come out
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Old 12-31-2003, 02:47 PM
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I'm done ignoring JW's advice, frankly, so I can tell you I'd be very careful and aggressive at the same time, based on his remarks above. That being said, I'd still probably use a reverse drill bits and a penetrant that eats corrosion, over several days perhaps. I'd give the fat screw extractors a chance, using ones that work as opposed to those crappy arrowhead-shaped things. I'd be tempted to work hard and slow enough that I'd dig threads out with a pic if necessary, to avoid the timecert option.
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Old 12-31-2003, 04:31 PM
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I just bought a MAP torche since it burnes hotter than propane and will be better to get studs out. I would try the heat method first and then go to drill it out.

Ingo
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Old 12-31-2003, 04:38 PM
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Quote:
Originally posted by Kurt V
I was going to mention the left-hand drill bits, but I have never found a set worth a crap!
I know that everyone here knows that Snap-On drill bits are crap but, their cobalt left-handed drill bits are really, really good. Alot better than anyone elses. They are obviously not made by the same company who makes their standard and cobalt bits. Where I work, we have been trying for years to find out who actually makes them so we don't have to deal with Snap-On, but they are on to us. The cobalt lefties have no problems with NAS or MS spec bolts in just about any material.

Just a thought.

Weaver
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Old 12-31-2003, 09:13 PM
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Still Stuck

Ran the heat treatment with Map gas several times.

Dilled 1/8" pilot hole, BP Blasted and then followed with small easy out and Snap-on screw extractor. Nothing.

Drilled 3/16" hole and followed same procedure. Nothing.

Drilled 1/4" hole and followed same procedure. Nothing.

The hole appears to be slightly off center now and I'm concerned about the threads. I ran a 5/16" drill bit in about 3/16" of an inch. Threads are ok, but I still can't turn bolt with any of the tools.

I decided to quit for a while and think things through. I guess the only option is to either drill on with the 5/16" bit and hope the threads are ok and that the bolt colapses. I don't think it will work as the bolt is frozen in and that's why it broke. It wasn't like external weight or pressure caused it to snap.

So assuming I'm correct I guess there is a procedure for drilling out and inserting a timcert. Can I do that? Also, the portion of the block where this is is not too meaty, so the replacement bolt would most likely be smaller, maybe 8M.

Advice?

John
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Old 01-01-2004, 09:01 AM
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Will a small triangular or knife edged file fit in there? If you can cut through one part of the remaining wall the bolt might collapse. if you file carefully you won't damage threads to any great extent, and even if you did you would be able to center your insert drill once the broken bolt is out.
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Old 01-01-2004, 09:38 AM
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Got a dremel? A dremel tool with a small burr cutting bit, like 1/8th inch can grind out the bolt, little by little. This work well especially when the pilot hole is off-center, which is pretty common with these type of repairs..

Grind it out slowly, flush the hole with air or someting to keep it clean and to track your progress. I am sure once the bulk of the bolt is removed, you should be able to heat it up again and pick out the remaining bits. If you get a few good threads showing, carefully run a tap to clear out the remnants of the broken bolt..

Good Luck!!

Chris
Old 01-01-2004, 09:42 AM
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are you spraying it with wd40 or something after you get hot???you should have it hot enough to stink up your working aera pretty good(in fact if it pops into a small flame once in awhile thats ok) just be ready!!
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Old 01-01-2004, 11:35 AM
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I recently had this problem in a small aluminum engine head. After drilling it out and breaking an easy out off in the bolt, I found that those spherical diamond dremel bits allow you to grind out what's left with great precision. And if your original hole is off center, you can correct that with the dremel also. The diamond bits are smoother than the carbide bits and are more controllable.

If you are rebuilding the engine, another option is wait until the case is split and take that half to a real machinist.
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Old 01-01-2004, 12:36 PM
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After you use a large enough bit to get to the threads, use some 1/16 to 1/8 bits to weaken the thick part of the bolt. Drill a series of holes next to each other all the way through the bolt, then use a vice grip to colapse the bolt enough to break the tension and you should be able to unscrew it. Lightly grind the end of the bolt flat so you can center punch your starting point.
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Old 01-01-2004, 12:47 PM
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If you put side force on the drill you can make it wonder over to center...then you can go in with your next o.s. USE HEAT AND YOUR FAVORIT spray stuff....every time you heat it and spray it as it cools dwn it sucks into it and this will loosen it up too.
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Old 01-01-2004, 01:10 PM
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Fixed

So I tried the Dremel route but just didn't seem to be getting anywhere. I figured I'd be drilling and tapping and using a thread repair insert. I went to my local Ace Hardware to peruse their drill bit and tap section. Surprisingly they have twice as much as Sears Hardware. I picked up a 13/32" bit, a M10-1.75 tap and appropriate bolts. Drilled and tapped very carefully and it worked like a charm. Then I enlarged slightly the bracket hole to accomodate the larger bolt. Mission complete. I though this would be much better than using an insert and a smaler bolt.

Thanks to all who provided suggestions.

John
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Old 01-02-2004, 09:03 AM
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O.k. , Try an E.Z.out.
drill appropriate size hole place e.z.out in hole turn counterclockwise. Then you are done.

I think sears sells them, they look like a tap but grab the hole. Works great

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Old 01-02-2004, 09:55 AM
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