How to remove a broken bolt in a deep hole | remove broken bolt in recessed hole

How to remove a broken bolt in a deep hole | remove broken bolt in recessed hole

In this video I’m going to take a look at a few techniques for removing broken bolts or broken studs which are deep within a hole. So I’ve got a stud in that hole that needs removing we’ve also got a sheared bolt just there that needs removing. If you see that all of these are below the surface. Then on this sump we have actually got a sheared bolt just there. The danger with trying to remove a stud like that or a broken bolt is the fact that the surrounding material is much softer than the bolt itself so obviously this is made from aluminium and the bolt is made from steel so the aluminium is much softer. Before you attempt to remove any broken bolt there are a couple of things that you can do that can make it easier. One of the first things you should do is try to shock it now I’m actually going to use a spring-loaded punch to do this so I’m just going to give that a few gentle taps. If you don’t have a spring-loaded punch like that you can use a traditional punch just give that a few gentle taps with a club hammer and that can help to free the broken bolt. can also apply some heat obviously you have to be careful if you’re using burning gear because you can quite easily melt the aluminium. You can also use some spray penetrant there is a good chance that will help. One thing that you could use is a hinge sighting drill they have a spring loaded part there which exposes the drill bit that will actually prevent the drill bits from catching the side of the material which you are trying to remove the broken bolt from. In sighting drills are normally used like that, you’ll position your hinge where you want it then you can simply use that to drill your pilot holes that will ensure they are dead central. However I’m not going to use it for that I’m going to use that to ensure that I can drill dead in the center of a sheared bolt. Take a look at that one for example you can see that that is in very bad condition if you try to use a normal chance at all of getting it started without drill bit on there you would have no slipping off and damaging the aluminium thread. For the first bolt I’m going to swap the drill bit over and I’m going to use a left-handed drill bit so I’m just going to push that in there I’ll then tighten the grub screw and then I’ll screw that back together. The actual drill bit that I’m using is a bit shorter than the one that I’ve taken out so I’m actually just going to remove the spring from that and that will still centre the drill bit. So if we try that in the end of the shaft you can see that it’s a very good fit and we’re not going to actually damage the internal threads on that. You can of course use a regular right handed drill in a hinge sighting drill but that will then mean that you will need to use a screw extractor afterwards. So I’m now going to flick the drill in to reverse and then we’re going So you can see that the left handed drill bit actually started to bite into that and it actually extracted it from the hole. If we take a look in there you can see that the threads are not damaged at all. A big problem with removing a broken bolt that is deep in a hole is that you don’t want to damage the threads in the surrounding material. I’ve actually made these which are socket head bolts and I’ve actually drilled a hole down the center of those using a lathe and I’ve actually made an M12, M10 and an M8. So we can now take this we can actually screw that into the hole where the damaged or broken bolt is until that is tight and then we can tighten up the nut that will prevent that from coming loose just gently nip that up and again I’m actually going to use a left-handed drill bit. The beauty of a left handed drill bit is that when it bites into the material there’s a chance that it will remove the broken bolt. So I’m just going to put some cutting paste on the end of that and ensure the drill is in reverse You can see that that has now started so I’m going to remove the bolt and we should have an indentation in the bolt so that should ensure that we don’t actually damage the threads on the aluminium and we should now be able to proceed and there is a chance that we will be able to remove this. Let’s give that a spray with some spray penetrant and I’ll just try again. It’s not actually been moving the bolt that time but we have got it far enough forwards now and in a deep enough hole to try a screw extractor. So I’m now going to take a screw extractor I’ll just tap that in there I’m just going to take a small adjustable, I would normally use a a tap wrench but it is at work. This time we’ve actually got that moving. It moves a little bit more, it has actually slipped out again. These are not the best quality screw extractors that you can get these were a very cheap set. I’m just going to go to the next size up. I’m just going to tap that in, and as you can see that has successfully removed the damaged bolt. I’ll just prove to you that none of these threads have been damaged. We can now take an M10 bolt and we can easily screw that back in there. With this one you’ve got absolutely no chance at all of starting the drill bit on it because it’s not at all flat. So the chances are that you’d skid off there and you’d actually end up damaging the threads. So I’m just going to give that a spray. I’m now going to take the socket head bolt that I’ve drilled a hole through the center, I’m going to screw that in there until it touches the broken bolt, I’m going to run the nut down and I’ll just nip that up. I’m going to use a cobalt drill bit for drilling the bolt because these are very tough. What we don’t want to do is go too deep into it because you don’t want to drill into the aluminium. So I’m just going to apply some cutting paste then I’m going to proceed to drill the hole. I’m now going to remove that and we’ll see how deep in we have gone. So you can now see that we’ve got that hole started and it is dead in the center of the bolt. Now that we’ve got the hole started in the dead center we can now continue to drill that without the guide in or if you aren’t confident about doing that you can always put the guide in. So I’m now going to take some more cutting paste and I’m going to proceed to drill the hole. So we’ve drilled approximately seven to eight millimeters in that bolt. What we don’t want to do is go too far in there and go through the actual aluminium casting. So I’m actually just going to try the screw extractor on that now. I’m just going to tap that in using the hammer and then I’m just going to undo that using the adjustable spanner. It does actually look like that has bit. Normally I would use a tap wrench for doing this but unfortunately it is at work. As you can see that has been removed successfully. We will now just try a regular M12 bolt back in there just to prove that the threads have not been damaged. You can see that that goes in there perfectly. Obviously before you go putting any bolts back into components like this it’s a good idea to give them a good coating using some copper grease or anti-seize compound. If you do that you can virtually guarantee that the next time you come to remove the bolts they’re not going to seize up and they’re not going to snap and you will be able to remove them very easily. So that’s a couple of techniques that you can use to remove bolts that have been broken deep in holes. I hope you found this video useful if you have and you haven’t done so already please subscribe to the channel.

About the Author: Michael Flood


  1. Great ideas. Usually on broken bolts they come to you after they destroy it with a punch and expect you to get it out.

  2. I have removed a lot of broken exhaust manifold studs and have found that by drilling right through the offending stud/bolt it kind of shrinks the stud a little and makes the extraction much easier, also I used a parallel shaft extractor which worked every time, I believe that the tapered ones expand the part you are trying to extract thereby making it more difficult. Nice video though.

  3. Excellent thanks for time you took to demo this ,and now i have to remove the remains of a star bolt from an alloy casting on top a mercedes strut where they use some kind of coating to seal the bolts !

  4. I haven't had much luck with these methods. Mostly because i am not the best at controlling the drill. If you happen to be like me and its a easily removed and transported part. Take it to the local machine shop and get it removed without first trying it. If you mess up the hole or broken bolt then they may not be able to help

  5. That is brilliant. I think I’m going to make myself a set of centering bolts on my pillar drill tomorrow.

  6. I'm 56 born July 4th, 1963. I've been working on all kinds of things bicycles cars you name it and all my life, never seen these techniques before extremely smart thank you.
    God Bless 🙏😇 Y'all Jimmy in NC….

  7. When using the screw extractor (or "ezi-out" as sometimes called) it is best to do so vertically so you can apply pressure downward whilst using the wrench to turn it. The pressure helps to press the extractor into your drilled hole. Yes, I have used this technique several times. Can also be used to remove a spark-plug (centre electrode broken out) from a cylinder head. Use plenty of grease to catch metal shards that may otherwise enter the cylinder.

  8. Thanks mate!! I’m going to be using a combination of these techniques to get a cylinder head bolt out that has sheared off in the engine block of my Subaru WRX. Never thought about combining my left handed drill bits with my hinge guides! May end up making some of those bolts with through holes and locking nuts for this project!

  9. Excellent video.
    I don't know why I'm watching this, I seem to have become an expert at removing broken bolts over the years.
    Friendly advice: When tapping the extractor into the bolt, I grab the extractor with Vise Grips and apply a bit of counter clockwise torque to nudge it in tight. Works like a charm!

  10. Like all your other videos …… simply brilliant!! You’ve got me out of jail countless times with your knowledge & skills. Thank you 👍🏼⭐️

  11. Fab. A great watch. Thanks.
    Was the last bolt high tensile? I’ve taken the head off a high tensile bolt that fastens the front (chain) sprocket to the drive shaft on a motorcycle. It is now recessed and the shaft turns, of course which adds complication.. Any tips would be gratefully received.
    A very satisfying watch.

  12. I got some broken bolt with something similar, the bolt broke inside the hole, and I also like you to apply the drill hole and extractor on the broken bolt.

    I had spray penetration oil and made it soak in oil for about 30 minutes then I tried but the bolt really stuck that I even break the extractor into the broken bolt too!

    I almost lost hope to it, or any suggestion?

    Thank you for reading!

  13. Thanks! Did this years ago on a valve cover bolt. My hole was way off center but the easy out still worked; however this time I need more help as the hole is deeper and a higher torque bolt. I will be at the parts store in a minute. Hope I can find something that works like your hinge starter tool. 🙂

  14. I need to remove aluminum bolts from the bottom of my block on my bmw. Are aluminum much easier because of how light the metal is? Im thinking of using this method.. definitely do not want to pay BMW if i can do the job for hardly any $$$

  15. As a mechanic I have worked on Army tanks and other tracked vehicles along with semi trucks. Worked for a dealership working on cars and trucks. The last 35 years I have worked on aircraft from the auto pilot to the toilets, currently working in the engine shop building Rolls Royce RB211, GEnx-1B, and CFM 56-7 turbo fan jet engines. So I have seen a lot of tricks to get things done that only a quality result acceptable. I can measure down to millions of an inch using a lens and lights. So my experience is quite broad. You have taught me a few new tricks which is rare. I knew about left hand drill bits as I have had many call B.S. on that lol. The hinge guide was a slick trick . The center drilled bolts as guides was a nice professional touch. Excellent video.

  16. Will using copper never seize on a steel bolt put into aluminum cause a chemical reaction, or breakdown that will deteriorate the bolt or aluminum part and cause problems down the road?

  17. I'm trying to split a scooter engine (GY6 50cc) made from aluminium to replace the timing chain. I've removed the only bolt that holds the parts together but they're still stuck and I can't separate them. Any advice?

  18. The worst are exhaust manifold studs that break off flush. I know. I drilled out many Porsche 911 studs and what was the real challenge was when Audi came out with the 5 cylinder. They all broke off the studs on #5. Thus, to do it in the car took a 90 degree air powered drill and a mirror taped to the frame rail. You had to learn how to drill while looking at a mirror.

  19. can someone please tell me what part of the engine that is my Honda pilot is cracked where the alternator bolt is supposed to go into so no matter how many times I changed it it keeps breaking the bolt n belt comes off

  20. The most difficult bolt removal I experienced was removing a dead axle from a Cat D-4 dozer. The dead axle broke off even with the bulldozer frame. Not even tweezers could grab it.
    We welded a 2" steel rod to the exposed part of the dead axle (which is a giant bolt). On top of the steel rod we welded an X with enough over-reach to allow is to put 4 10 ton jacks under the X. After jacking each jack until it groaned, we put a 55 gallon barrel full of water in front of the bolt and a week later, it turned loose. The dead axle traveled thru the 55 gallon barrel full of water, thru the shop wall, thru two empty 55 gallon barrels and came to rest about 150' away. Bazinga!

  21. I've had some luck tapping torx bits into the drilled holes, particularly in softer materials such as brass pipe fittings and broken zerk fittings. The issue I have with round extractors is they expand the broken piece inside the hole and make it more difficult to extract. Mac Tools makes square extractors that don't expand the broken piece. I've had good luck with them also.

  22. There may well be a kit for it already, although I've never seen one, but I think money could be made offering an assortment of those bolts with center holes drilled through them, a few tubes for the same centering purpose, a few good quality reverse drill bits, and a few screw extractors. In my days of working on vehicles I've struggled with this issue and some of these methods might have helped

  23. Hello my brother in-law try to remove the broken bolt be just made it worse by braking the extractor in there too. Can you tell me what I can do?

  24. bee's wax works better at freeing seized, rusted, stuck, broken and otherwise difficult to remove fasteners than almost any available commercial product. Once you heat the area, float some bee's wax into the stuck fastener area. Do it more than once. The capillary action draws the bee's wax into the area between the fastener and threaded material. When it cools, the fastener will come out with very little torque. We use this kind of technique in marine maintenance and machining, and older automobile restoration. Bees wax, unlike candle wax, and 90 % of the commercial penetrants has a much higher burn temp and does not carbonize like most of the petroleum based penetrants.

  25. Those left handed bits, we have whats called "easy outs" that are like that but made to extract broken bolts… Except you don't use a drill you use a wrench on them, doesn't take much turning to latch on, especially if u drill it a little with a normal drill bit before hand.
    Never mind you showed one that you call a screw extractor.
    Whats the reason for safety glasses? hehe.

  26. Hello, where in gods name would you purchase a left hand drill bit? I have never seen these in local hardware stores. I would be hard pressed just to find left hand threaded bolts. Thanks

  27. The AEG 18V cordless drill in the UK is the same as the Home depot Ridgid 18V system in the USA. Both are made at the same factory in China, both batteries interchange. The chargers in the UK are for 220 volts

  28. The tap handle method allows one to keep pressure on the extractor and also places pressure on either side for better control.
    I sometimes use small endmills to "flatten" the broken surface. A tube or pipe will usually suffice to keep the threads intact.

  29. When the screw extractor breaks its such a chore to finish the job. Im impatient…gets me into trouble with machines a lot. They dont enjoy lack of patience too much.

  30. My broken studs are usually rusted in and inaccessible. 🙁 I had a broken exhaust stud that resisted removal for a week of evenings. I was left with a nub protruding, I couldn't weld a nut on, socket head screw extractors just slipped. In the end, I bought a set of left handed chuck jaws. Did the job in seconds. Never used them since, but it don't matter, they're so beautiful that they sit on my mantlepiece as ornaments! 🙂

  31. Just bunch a bit center drill hole re reverse thread put a threaded bolt in and the broken one threads out faster then this work

  32. Newbie question: What is cutting paste? Is that used to prevent seizing of the drill bit so that the tip doesn't break off?

  33. Have to be very careful with those screw extractors, and know when to stop. Normal drill bits won't drill through them if it gets broken off in the bolt

  34. Great idea making the drilling guide, I will start on those tomorrow. I have found that when I am having trouble getting the extractor to bite into the metal, I put a bit of torque on it as I hit it with the hammer, tends to get a better grip that way. Thanks for the ideas!

  35. Ahhhhh but when the bolts snap off at the edge of the hole so you have NO threads to screw your little guide into….. and the bolts are grade 8…. Not mild steel…… 🤦‍♂️🤦‍♂️🤦‍♂️🤦‍♂️
    Nissan RB motors…… Damn you Nissan!!! Every time..😡

  36. the point been how to remove any broken bolt ! having those new fancy tool removals doesn't help! how in the old days they use to do it? with not modern tools we don't have in our tool box!

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