Broken bolts are a PIA. Which bolt broke and how did it break, flush with the head, some part still sticking out, as removal is different?
My first step on a broken bolt is to take a center punch and mark the center of the broken part.
If part of it is sticking out I like to clean around it, then use a torch (propane is fine, butane even works) to heat the bolt. Now take a candle and place it against the bolt, the wax will melt and wick into the threads. Clean and heat it again. Then use a pair of vice grips to grab the stub and gently try turning it in both directions. Once you get it moving it will usually screw out.
If it broken off flush, it's a bit more work. Get a set (or just the sizes needed for the bolt you have) of LEFT hand drill bits and a couple broken bolt extractors to match.
Proceed as above except you don't use the vice grips. Instead you will pick a drill about 1/2 the size of the broken bolt. Now drill in the center of the bolt and stop when you get to the point that an extractor will actually grab. Now place the extractor in the hole and tap it with a hammer STRAIGHT in, don't break the extractor. Now gently try unscrewing the bolt. If it doesn't come out with light force. Remove the extractor and heat it again. Repeat until it comes out.
IF you have a welder and the bolt is broken off with some sticking out, you can take a nut, place it over the broken bolt, weld it in place and they usually will come out.
Or you can just drill it out and install a heli-coil to get the threads back.
Sunday, December 25th, 2016 AT 6:49 AM