How To: Broken bolts - guide to removal using a welder

[Kenny_Z]

These aren't Delorean heads but they are aluminum. They're from my 99 Monte Carlo and I found three of the twelve studs snapped off when I removed the head shields. I broke the fourth while trying to back out the stud.

As you can see I tried to slot the bolt and back it out with a screw driver. That plan failed pretty quickly.
http://uploads.m-cgi.com/kennyz/monte/bolt01.jpg

I got a washer and a nut. The washer is just a little larger than the bolt. This gives me a gap to pour a little more heat into for better weld penetration without worrying about too much heat on the aluminum.
http://uploads.m-cgi.com/kennyz/monte/bolt02.jpg

Obviously the welds don't have to be pretty. At this point my welding gas is running a little low.
http://uploads.m-cgi.com/kennyz/monte/bolt03.jpg

I set the nut on the top of the weld and made a tack on the inside just to hold it in place. I found that starting your weld on the nut and then pulling it down to the edge of the washer works best. Also make sure your washer is larger than your nut. The one below ended up ripping apart the washer and I had to get a smaller nut.
http://uploads.m-cgi.com/kennyz/monte/bolt04.jpg

I was able to successfully remove all four broken studs without drilling or grinding.
http://uploads.m-cgi.com/kennyz/monte/bolt06.jpg

Couple of notes: Give the welds about half a minute to cool. Then take a hammer and lightly tap on your wrench as you apply pressure to remove the stud. When you feel it give stop and take a look to make sure the bolt is actually turning. Like I said before, I tore a washer and the nut gave way before the stud. If you see the weld breaking stop and reweld. Be careful you don't get too much heat into the heads or studs. The two metals have different expansion rates. BE MINDFUL OF WHERE YOU ARE. These heads were out of the car. If I had to do this in the car I'd watch for things like oil, fuel lines, and rubber components.

I think this will work with studs sheared off level with the rest of the surface. You can use a high heat and slow wire feed to put a bubble on top of the bolt without getting into the surrounding metal. Let the bubble cool and then weld it to the washer. I hope I never have to test that theory.

[Nicholas R]

This is pretty awesome!!! I will definitely keep this in mind from now on.

What kind of welder did you use? Just curious because I know some hardware is very difficult to weld because of how hard it is, how it's coated, etc. I'm not sure my MIG welder would get enough penetration. The TIG/STICK welder on the other hand would likely have no problem. Anyway, just curious what you did. Well done!!!

[Mark D]

Pretty awesome method for extracting broken bolts/studs!

Sure beats the hell out of drilling.

[Bitsyncmaster]

I like your idea of using a washer first. Never thought of that. I have welded nuts on stuck bolts a few times with great success.

[Spittybug]

Nice tip. I would ask the same question as Nic above.....

[Kenny_Z]

I'm glad you guys like this. I hope it helps. I tried to weld the nuts onto the studs but I found that I filled the nut with weld before I could get enough heat to penetrate the bolt. That's where the idea of the washer came from. I could build heat on the bolt with a weld puddle and then pull it to the washer when it was secure.

I've only got a MIG welder. It's a 110v Lincoln from Lowes. I used the second hottest setting with a medium-low wire speed to get the penetration. A TIG would have been much better but I do not own one yet.

[Bitsyncmaster]

The MIG makes the heat in a smaller area than a TIG so I think the MIG is better for this type of work.

[Nicholas R]

The MIG makes the heat in a smaller area than a TIG so I think the MIG is better for this type of work.

I disagree with that. Nothing is more precise than a ground tungsten electrode. My TIG welder has a remote pedal that allows adjustment of the current from zero to the maximum you set while welding. While I love the convenience of my MIG, it doesn't come anywhere close in terms of quality and precision. One of the biggest challenges with MIG is that you HAVE to keep moving. Also, like Kenny_Z, my MIG is only 110 volts (the TIG is 220v) which really restricts how deep you can penetrate and how thick the metal is you can weld. If you really want to weld thick stuff, you have to both bevel the weld area and/or preheat the workpiece.

[Bitsyncmaster]

I agree TIG gives you the best control and prettiest welds but the fact that MIG is done so fast means there is less heating of the surrounding area. MIG can use less power becuase of that fact.

[Kenny_Z]

I haven't found anything my little 110 MIG won't weld. I repaired the frame on my Nova project with it. It was one of the easiest welds ever. I think a 110 Mig is fine for normal car restoration. If I was building a roll cage I'd step up to the 220. I'd love to have and learn how to use a TIG but mainly for aluminum and stainless welding. I'd like to do more of my own exhaust work.