PLEASE HELP! Broke a bolt off in the end of my crank!
I was putting an underdrive pulley on my crank today, and I was using a long bolt to pull it on. The pulley started going on, and I was putting some serious pressure on this thing, trying to get it to seat. Then all of a sudden the long bolt snapped down by the threated area... and I'm ****ed. Can anyone tell me how to get this bolt out?
If the broken part is flush, or in the crank threads, you will probably need to drill a small hole in the center of the broken bolt and hammer in a screw extractor (EZ-out) to remove it. Get the kind that looks like a tapered square, they work better and are less prone to breakage than the corkscrew looking ones.
With no pressure on the threads, if it broke off flush, it should back out fairly easily. You can also try using a very narrow chisel and trying to aim it counter clockwise off-center on the broken bolt to get it to spin out...sometimes works, usually doesn't.
Hate to say this, but the bigger issue "may" be the threads are also probably messed up. Try getting the old one out first. Then make a tool to re-install the new pulley. Not sure on the one are installing, but the ATI requires a precision fit to 2/10,000 of an inch. Here is the way to make the tool, it will engage all the threads. If it was only part way in, you "may" still be OK by using a different bolt length so you can catch the threads farther in the crank. First get the old one out and then assess the situation.
Hate to say this, but the bigger issue "may" be the threads are also probably messed up. Try getting the old one out first. Then make a tool to re-install the new pulley. Not sure on the one are installing, but the ATI requires a precision fit to 2/10,000 of an inch. Here is the way to make the tool, it will engage all the threads. If it was only part way in, you "may" still be OK by using a different bolt length so you can catch the threads farther in the crank. First get the old one out and then assess the situation.
Likely, the threads stripped, causing you to use more and more force, and bang. So, don't think you'll be getting that out with any extractor. It's in there. Plan on drilling. Start with a small pilot hole (making a sleeve/guide to center the bit on the crank is a good idea).
Keep working it out till you are using larger and larger bits. Dewalt pilot point bits work well, and use lots of cutting fluid, and take your time. I agree with vettenuts, asses the situation once you get your bolt out. Run a chase once it's out (clean your chips out good) and check the condition of your threads. Even if some of them are bunged, you may have enough at the back of snout to still get the torque you need. Especially if you are keying/pinning the crank (won't require as much torque).
Total worse case scenario, you can 1). drill the ID of the snout one size bigger and use a helicoil, or 2. use the std ID of the snout to cut 3/4-16 threads (it's just every so slightly larger than spec for said thread cut, BUT, it's enough to make it work) and you can use a 3/4-16 thread pitch bolt.
So you've got some options, so don't think hope is lost, it may just take you awhile to salvage/inspect, and take your best course of action depending. Keep us posted
2/10,000 that's ridiculous. LOL for the stock pulley GM says between 2.48-4.xx mm is the acceptable distance from the snout to the inner ring of the pulley. Definitely use a threaded rod. I ended up buying the Kent Moore seal installer and used that threaded rod along with the balancer installer. It was a little short, but it got it done right. I ended using a thrust bearing as well to help with the friction.
I hope your luck turns around Mike, at least this isn't nearly as bad the rocker pedestal incident.
I hope your luck turns around Mike, at least this isn't nearly as bad the rocker pedestal incident.
Haha, no I suppose its not, but this is pretty far up there I got some tools to remove bolts, I'm gonna give the ez outs a shot in the morning. I'm starting to wish I kept my Camaro instead of this stupid car, its been nothing but problems.
Last edited by Mike94ZLT1; 06-10-2007 at 12:04 AM.
You've already got a lot of good advice and some options on how to remove it.
I am surprised you havent seen one of the other hundred threads like this with similar outcomes. Most guys seem to be able to get the bolt out one way or another....Im sure your situation will be the same.
There is only one way to pull a dampner on a crank and thats with the use of a proper installer or the use of a threaded rod which is essentially what the proper tool is. When you finally get the broken bolt out and the threads reasonably clean (you may need to purchase a tap) thats what you will need to use. I will post a pic of the simple set-up you need in the morning
2/10,000 that's ridiculous. LOL for the stock pulley GM says between 2.48-4.xx mm is the acceptable distance from the snout to the inner ring of the pulley. Definitely use a threaded rod. I ended up buying the Kent Moore seal installer and used that threaded rod along with the balancer installer. It was a little short, but it got it done right. I ended using a thrust bearing as well to help with the friction.
I hope your luck turns around Mike, at least this isn't nearly as bad the rocker pedestal incident.
That is the interference fit between the inner diameter of the hub and the crank snout. The actual numbers are 0.0007-0.0009" interference fit.
By far the best way to remove any broken bolt if you have to drill it is to use a left twisted bit. You must also have a reverseing drill. Since the bit is digging into bolt counter clock wise more often than not the drill will dig bolt out. If it dosen't you still have a hole for the easy out. What ever drill method you choose start out small and take your time. Getting in a hurry to fix one problem often creats another problem. You will be OK. Good luck. Frank
Haha, no I suppose its not, but this is pretty far up there I got some tools to remove bolts, I'm gonna give the ez outs a shot in the morning. I'm starting to wish I kept my Camaro instead of this stupid car, its been nothing but problems.
Ha, off topic, but same here!! My Corvette has been nothing but a PITA since I got it. My 99 Camaro SS ran like a champ! Even though just changing the spark plugs was an ordeal... It was still a more mechanically sound car. It shifted way smoother too. In fact the guy who bought it just sent me an email and told me how awesome it is still running. In fact it did 353 RWHP with just long tubes and a better cat-back (it did 311 when I had it).
Now I'm ****ed... EZ out broke off in the hole. I'm gonna go dig a pit, shoot myself and fall in.
I'd probably do the same thing... I broke an EZ out yesterday trying remove a broken bolt that holds down the dipstick tube on the header... I put the header on anyways. I was just thinking of you too buddy. I thought, "I hope to hell that EZ doesn't break on him" It probably would have happened to me too... I'm hard on tools.
Drilling out an EZ out is almost impossible
Well, I'd buy you a beer... hell a 6 or 12 pack after that man.
I just pray my car runs right (it's getting close to being done), or I'm going to go Camaro shopping with you. Again, sorry man...
Do you know the length of the bolt you broke and then how much was left? This would be an indication of how much in still in the crank. If you can get the easy out removed, you may need to just keep drilling it bigger.
What happened is that the longer bolt bottomed out in the hole and, as a result it had big bunches of residual torque on it even after it was broken off. That's why the ez-out couldn't get it out. Also, the last few threads of the hole are always not very good, so you end up with a distorted thread locking feature at the end of a highly torqued bolt....
My experience with these things (and there have been a couple), is that it is better to get a few drill bits of increasing sizes, grind the end of the bolt flat to get a good center punch on it, and then start with a relatively small drill and work your way up until you are just about to the threads. Generally then it will come out, about the time you start breaking the edges of the inside of the threads.
Now you are pretty much screwed. Time to take the crank to a machine shop, or maybe an EDM house where they can burn it out...
I usualy use wire feed welder and weld on a bolt to the end of the broken bolt and do it that way to remove it.. since now you got the EZ out broken in there there is no way of drilling it now.
The other option that a few have used is to thread the larger unthreaded section of the crank before the original threads started. Hope this makes sense, but it may be your only alternative at this point.
PLEASE HELP! Broke a bolt off in the end of my crank!
I got some tools to remove bolts, I'm gonna give the ez outs a shot in the morning. 
