How to Remove a Broken Bolt

Contributed Article

Talk of the Town:
How to Remove a Broken Bolt

Another great discussion from the Tractor Talk Discussion Forum.

The discussion started out with the following post:

"I have an aluminum steering gear housing with a bolt broken off in it. The bolt is about a 3/8" x 1 1/2" bolt. I've already drilled the center of the bolt out with about 7/64" drill bit the entire length of the bolt. Only one end of the bolt is visible. I tried to use an easy out but it wasn't budging and I didn't want to break the easy out off in the bolt. Can I heat aluminum? Can I try to weld a new bolt head to the bolt? Should I just drill it out completely and use a heli-coil? "

What followed are some interesting replies:

" I have taken many stuck bolts out when I farmed by welding a stud bolt with the threaded end tapered on a grinder, then weld the sucker to the itty bitty stud sticking out, maybe- even if it was slightly below the surface I welded it, if you are unsure with your welding use a stainless steel rod to make a stronger weld, make sure of no flux impurities in the weld, the action of heating that thing up with the weld also helps to loosen the rust, works 9.5 out of 10 times for me. "

" One thing you might consider- beg or borrow a stick welder, if you do not have one yourself. Find a nut that is approximately the size of the broken bolt head, place said nut over broken bolt, fill nut with weld, thereby welding the broken bolt to the nut from the inside. Let cool. This essentially creates a new bolt head, huh? I have done this a couple of times. "

" Two more things to consider -- The most common "Easy-Out" are the ones that screw in as they are turned. A nice idea I suppose, but I've thrown them out or have given them to someone I don't like very well. As they screw in they also exert pressure on the side wall of the broken bolt, most of the time causing as much damage than just drilling the bolt. I've been using the square shank easy-outs with much better success for leaving the hole threads intact. The other tool I've used with pretty good results are a set of left-handed drill bits. Since the bit is turning in the direction you want the bolt move it will often times come out without any additional work.The bits are hard to find sometimes, but well worth it. "

" Excellent advice. I need to find some people I don't like to give my screw type "easyouts" to. I have found them to be less than useless. Withe the bolt seized so tight that it broke off, what chance does an easyout of less diameter have? When the break is in steel I resort to my welder with good results. I'm tempted to try the arc welder on the aluminum next time. Actually, the anodizing (mentioned in another post) sounds like an excellent idea for those extra tough ones. Drill out till you are near the threads and the eat the steel away with the anodizing process! I can't say I'm looking foward to the next time this happens to try it, but it does have my curiosity stirred. "

" Please keep in mind....."Easy-outs aren't" Be careful with them! If you break one off, you have just created a bigger problem than you started with. I trashed an engine block with a broken easy-out. The bolt will drill out nicely and allow you the option of inserting a threaded sleeve. Once an easy-out is busted in place you can no longer drill it out. The easy-out is made of some pretty hard steel. I never put anything larger than a tap handle on one anymore. The advise in these replies is good stuff, just go easy. "

" The easy out for a 7/64 drill is pretty small and I'd worry about breaking it. If the current hole is in the center, drill it out for a larger size easy out. This will let you work it harder without worrying so much about the easy out breaking. If this doesn't work just drill it progressively larger. It may loosen when you get closer to the edge, or if it doesn't, you can just drill it out. I suggest that you don't use a heli-coil though, they are junk, especially in aluminum where they can partially pull out. Use a key-insert, it's a solid steel insert, threaded on the inside and out, it has little keys that you hammer in which keeps it from unscrewing. They are available from most industrial suppliers. "

" I don't know where to get it, but nitric acid will eat the steel bolt and not touch the aluminum. It will also eat flesh, lungs, clothes and the like. Otherwise penetrations of penetrating oils such as kerosene, wd-40, liquid wrench, and pierce (the best of the lot that I've had succes with, kerosene and WD-40 seem equally ineffective) are more effective if the stuck parts are violently jarred to open up a crack in the corrosion for their entry. But don't peen over the ends of the bolt to make a rivet! Have you considered retapping the hole in the steel, say for a 5/16" bolt and then put a sleeve around the bolt in the other piece? The heat of drilling and tapping may loosen the stuck bolt or just prove its really stuck. You can heat aluminum but not violently, it melts before it glows. Aluminum does expand faster than steel so heat is one way to loosen up a stuck bolt. Better with a hot air gun than acetylene or even propane. "

" Have you actuallt tried the nitric acid? It sounds like it might work. I hate to see steel bolts in aluminum, I've spent hours with similar problems, I guess stainless bolts or anti-seize compond cost too much for the people building this stuff. "

" If it's broke off down in the hole a ways, get a short piece of copper tube that fits the hole, turn up the welder, run the stick down into the tube and weld into the end of the bolt (the weld won't stick to the copper, and you won't melt the aluminum threads, then get on the copper tube and try to take it out with a small pipe wrench: : : I have an aluminum steering gear housing with a bolt broken off in it. The bolt is about a 3/8" x 1 1/2" bolt. I've already drilled the center of the bolt out with about 7/64" drill bit the entire length of the bolt. Only one end of the bolt is visible. I tried to use an easy out but it wasn't budging and I didn't want to break the easy out off in the bolt. "

" The nitric acid should work. The anodizing process uses acid, often chromic, phosphoric, boric or sulfuric acid. I once had some aluminum parts made for a project at work (I'm an engineer in the aerospace industry) and the mechanic who built them thought he could save some time by installing helicoils before he sent them to the anodize shop. When they came back, the helicoils were gone. The acid in the anodize tank ate them clean away. It might be interesting to try this with with muriatic acid, which is not as corrosive as nitric acid, and cheap and easy to find. Better protect any close tolerance areas, though, as the acid may have an effect on bare aluminum surfaces. Maybe you could just send your gear housing out to be anodized? "

" Merck Chemical index says aluminum "Reacts with diluted muriatic acid, sulfuric acid, pottasium hydroxide, and sodium hydroxide with evolution of hydrogen. So Muriatic would be a BAD idea. But Muriatic acid would eat steel. "

" The anodizing process uses the acid + an electric current. If done right will put a protective coating on the aluminum. "

" I've not tried nitric acid, but I've read about it many times for just this application. Its far less violent than breaking easy-outs. The left handed drill bits are a good idea though right handed will work too if its a through hole. More than once, I've carefully worked my way up in size to the tap drill for a bolt and had the remains spin out a few sizes before I got there. That was probably taking a 32nd of an inch diameter per drill bit, if I was lucky. And the bolt was in steel. I break taps in aluminum and there the nitric acid would be handiest. Far neater than neglecting that hole in the assembly. I broke a large easy-out in a 5/8" bolt last year. Turned out it had been locktited in place before it broke off flush. The solution (in a steel casting) was that I used up several small grinding bits in my air die grinder and slotted the threads but with the bolt in two or three pieces it came out peacefully and I passed a tap through the threads to straighten them up. "

" All of the above are options but the best one is the easy out and lots of patience. Can you soak the bolt with liquid wrench so it is just sitting immersed for a time? Put the easy out in and use a breaker bar on it with a eight point craftsman socket of sufficient size to fit the square easy out. If anything breaks it will be the socket and Sears will give you a new one. I had a similar problem last month and this is what worked for me. "

" Thanks for all of the advice. I never did get it out. I ended up just drilling it out and tapping to the next larger size bolt. It looks good and is functional. I ran into an interesting phenomenom though. While tapping the aluminum for the new bolt, I sprayed the tap and the hole with silicon for lubrication and cutting ease. The silicon reacted with the heating aluminum. A bubbly black ooze came off the the aluminum. It smelled like an acid. I don't know what happened but I don't think it was good. "

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