HELP! broke off a Grade-8 bolt inside my block, What drill bit do I buy to remove it?

I think you can Chris, but I don't know enough about Dodge Hemi blocks to know if you can or can't. Hindsight being 20/20 I should have gone about mounting the motor & tranny in a completely different way.

The dilemma I have is do I tear everything apart and take the motor & frame down to bare metal and start over again. Or do I slap the car together and drive it under it's own power for the first time in 40 years this summer, since I have 90% of what I need to make it run and drive. Then blow everything apart this winter, and fix all my mistakes.

 

It's not too late, not gonna hurt much to drill the 4 out and tap em.

 

Sounds weird but I've had a lot success getting snapped off bolts out by using an air driven engraving tool. You know the ones that you write your name on your tools with at work. As long as the busted bolt isn't bottomed out it should walk it right out.
Worth a shot, before getting the welder out.

 

Engineman, what would you think of tig welding a nut on it? A Allen screw is same spec as grade 8. I've gotten a lot of broken bolts out for friends with a Dremel. I use, don't tell OSHA, an 1/8 endmill in my Dremel and CAREFULLY borrow into the bolt, then mill sideways until I see threads forming a T slot. Then use a screwdriver to remove the broken bolt. Sounds dangerous, and probably is if the endmill grabs it brakes. I have warned everyone I know NEVER to bring me anything with a broken drill or easyout in it. Patience is the key!!

 

I used a Craftsman version on a broken bolt on my 327............... Worked will.

 

Sorry guy's, you can beat me like a rented mule, it really doesn't matter. I would never ever weld and put current through a completely assembled engine. Not one that I built. Again, that's just me, I'm sure a thousand story's are out there that people have done it and it was fine, its just my take on the welding deal. Its kind of like an unspoken rule in our race engine shops, you just dont do it. TR

 

I've heard that a guy that is good with an acetylene torch can use a cutting torch and
heat the broken bolt remnant to bright cherry red and then with a oxygen shot from the cutting torch, blast the remnant out of the hole without damaging the threads.
Allegedly the blocks mass dissipates the heat from the torch much faster than the stud can and the block is not damaged by this procedure.
Kind of sounds like it might work. A really skilled torch man/shop might know.
With the engine out you have the option to take it to a really good machine shop.
You can redo the paint job this winter after solving this problem. It can be done!

 

At the least, you should up the 5/16" by drilling/tapping larger. Like Chris said, it's not that big a deal (as long as the Hemi has the meat there to accomodate the larger bores). Possibly, this can be done w/o pulling the engine? Upping the size takes care of trying to remove the broken bolt-it gets bored out on the upsizing, though I wouldn't feel confident with 3/8" and I'm not sure that area could take 7/16".

I'd still favor side mounting the engine and never have to worry about snapping the front timing cover bolts again. If you go this route, you still need to get the broken stud out in order to seal your timing cover.

I wouldn't worry too much about applying heat to the block or welding in some side motor mounts to the frame (with the engine in place). Gloss black touches up real fine and folks will be gawking at your Hemi not looking for gloss black touch ups on the under portions of the engine area! Spray bomb it if you have to and shake it down and enjoy it during the Summer. You'll probably have some other crap on the hit list by then when you blow it apart next Winter.

 

Chrysler industrial hemi engines used a front mount attached on top of the bottom four timing cover screws (same 5/16" dia and pattern as your Dodge engine). The only difference there is that they support only the engine weight (not engine torque) as the mount has a single bolt centered below the vibration damper. Just food for thought...

 

This is true ^^^, but how do you know if the guy with the torch is any good or not??? I wouldn't want to find out by letting any yayhoo experiment on my stuff...

 

Keep in mind many early dodge engine blocks did not have any provision for side engine mounts...

 

The reason the torch will work is you can't cut cast iron with a torch, only steel. But the OP said he didn't want to use heat.

 

I realize you don't want to use heat, and some have said no welding. Others have suggested welding a nut onto the exposed part of the bolt.... By looking at the pic, the bolt is almost 1/2" below the surface. My suggestion, I was taught this by an old farm mechanic, is to use an arc welder, with a 1/8" rod and hook the ground very near the bolt area, so as not to run electric across the bearings, and just purposely stick the rod to the bolt. If you can stick it to the bolt, a set vice grips should back it right out. You already have drilled a small hole in the middle, so aim for it. As soon as you stick it, unhook the stick holder from the rod to minimize energy flow and good luck, no matter how you end up trying to get it out.

 

I still recommend a extractor personally, but you can always try JB Weld and a smaller diameter bolt (so jbweld doesn't get in the threads) and fuse them together since it's a cold process and you want to avoid heat. Then you can try to back it off like normal and then chase the threads with a tap with the hopes you have additional threads above the mating area as a guide to clean the whole thread up, regardless of it being a blind hole or not...

Also spray PB Blaster prior to doing ^^^

Edit: if you do use heat, use a sure-fire style torch with propane or mapp gas and do it carefully, you can apply heat and not hurt the finish since the flame is easy to control....

 

If your plan is in fact to step the bolt size up, determine what you will be taking it to. Drill that size hole with a LEFT HAND BIT. I'll take odds on it coming out easy peasy. You may have to dremel the partial bolt flat or concave so the bit won't walk.

Another option is to dremel a slot in the bolt and modify a hand/hammer driven impact screw driver tip to fit down in the hole and into the slot.

Be careful and plan your moves because in a situation like this, with your parameters, the more you do sometimes the less options you have.

 

I vote for the mig but use a piece of 1/8x 1 inch strap iron long enough to use as a handle drill a 5/16 hole in it to weld through. don't worry to much about the weld sticking to the block it's cast and the mild steel wire wont stick to it very well.

 

http://www.practicalmachinist.com/v...-removing-broken-hss-tap-w-tig-welder-225391/
http://www.fordgarage.com/pages/studremoval.htm
http://www.markthewelder.co.uk/id69.html

Its not very difficult I've done hundreds haven't been stumped yet. 6/32" to 3/4"

Can be done with some good welding smarts. Down the hole flush doesn't matter much. Tig should be your first choice on this one. Others will tell you different. Bin there done that 25 years tiggin has some knowledge behind it. Drilling, l/h bits carbide are almost a recipe for trouble you are at a point where none of these have worked for you.Take it to an accomplished tig welder and he will put a smile on your face.
My 2¢

Tig.

 

From the photo it looks like you are only down about one or two threads from the surface, is that correct?
Did the bolt bottom out in the hole and did you continuue to apply enough force to break it?
The reason I ask is if this is the case the remaining stud will be very tight so here goes-another writer suggested fragmenting the broken bit, very important to do that as to not include the particles in what I am about to say.
By not removing the broken bit you will find that the weld will become very brittle and fail.
Once the drill bit particles are outa the way use a TIG torch and build a pedastal from the remaining stud until you are high enough above the casting to get vice grips comfortably on, usually about 3/8".
I use 70-s-2 for rod, 3/32" tunsten out about 3/8" and very sharp, and obviously you don't want to hit any exposed threads that are remaining.
Make sure you ground the BLOCK very well as to not do any bearing damage.
Let the whole deal cool down to where ya can almost touch it and then start to work the bolt back and forth until it moves reasonably easy.
Once it starts coming out, keep it coming and you should be good to go.
I hope this helps, I have removed broken studs, rusted water plugs, etc using this method for years. Good luck. Ardeem.

 

I would try the welding route first. Lay a heavy 3/8 flat washer over the hole and then hit it with a stick...3/32 maybe, and lots of heat. Pile on the weld to fully grab the washer. Next, set a big nut on the washer and weld it on. Now, try to back it out while everything is still hot. This works 'most' of the time, but as noted, if the bolt was bottomed and then broken with a heavy hand, you might need to move on to this: strip it down to bare block so you can get it in a mill and cut a new hole for a larger bolt. This will require a damn good end mill.
If you have a fairly large horizontal mill available then you might be able to put the assembled engine on the table.

.

 

Payne,
I read through the post and every one will give you their opinion. Take your motor to a good machine shop and find some one there who can weld. You will need what is called a stud plus rod, they are stainless. then type around the hole, then build the broken bolt up a little at a time, the stainless will not stick to the cast block as long as you don't wild but a little at a time, by that I mean bump it and stop the keep doing this until their is enough to wild a washer to then weld a nut to the washer and slowly work the bolt out and in to help clean the treads. Also put a bolt in a hole close to the broken bolt to ground to DON'T WANT TO ARC ANY BEARINGS.
Any way good luck and if you have any questions you can P M me.

 

Have you seen these? Saw it demonstrated at the SEMA show. http://theoriginalrescuebit.com/

 

All of the sugestions can work depending on your skill set . the first thing you should do is get the broken drill out either by shocking or heating it up ,after that use the housing that bolts up to it make a sleve with a tap drill size then drill it out carefully if you if you drill into the threads i would go to mcmaster car and buy a keensert witch is a threaded adaptor that is 5/16 -18 id and 3/8-16 od ,this will give you a high quality repair now all you have to do is decide the fix that you want goodluck

 

There are companies that specialize in broken bolt removal if all else fails. I think they are called Metal Disintegration. Trying to get the broken drill bit out first seems to be the way to start.

 

Talk about 100 ways to skin a cat! I've never had any damn luck getting broken drill bits out, I would be calling your machinist or a local tool and die maker, find out if they want it tore down or assembled. I'm guessing it will be tore down so probably going to cost you 1 hour of shop rate at your machine shop and a new set of gaskets.

Cheaper than f**king up a perfectly good motor trying to half ass it out yourself.


Scot

***Edit, just realized I swore like 3 times and used the F-bomb, must be a bad day, oh and I really hate broken drill bits!***

 

Go to snap on tools web site they sell both left hand drill bits with ez outs part # EXDL10 and small burr bits part # VWB700A . I use them all the time at work to get broken bolts out. if you able to drill all the way through spray with pb blaster or aero kroil let set then try.

 

Amen hope he listens.

T

 

Patience is certainly the key. Very few people have the patience required. You need to take your time to keep from breaking bits.

A Dremel tool will work fine in many cases

The reason I use stick is that I have 40 years experience with it and I like having the flux to protect the threads both from the arc and the molten metal. Only the tip of the rod will arc and I can control the heat by varying the arc gap. While the tig weld won't stick to the cast iron, if you make any kind of a hole in the threads and that hole fills with weld, it will lock into the hole. Also with tig, you have to put 2 things in the hole.

 

Nice to see a post from a fellow welder and not some poster with a whole lot of useless info.You are correct about a steady hand and two things in the hole with the tig.
Your process will definitely work hands down.Tig is fun too because you can hang around a long time by backing off foot pedal and getting a good heat sink going. Stick when you hit the arc the game is on.You have to be a pro as there is no time to guess what is going on,you have to know.Not a job for a hobby welder at all.Take it to a welding shop and get an estimate.Did we cover patience (LOL)

Tig

 

I know that it has been suggested, the left-hand drill bit works very well, and it makes perfect sense.

 

This for sure is one of those cases where if you don't know what your doing take it to someone who does. Being a machinist by trade I would make a drill guide based off the other hole, something that can be bolted to the block so the drill can't walk. Then it's a matter of a carbide or left-hand drill. Slow and steady and out it comes.