removing broken bolts
removing broken bolts
Seems like everyone has chimmed in here, so I'll add my two cents. Some of the stuff above isn't exactly good sound advice, some is.
First, definitely finish removing the head. A few taps with a soft faced dead blow hammer should do the trick. When tapping the head, alternate from one side to the other. Using wooden shims as previously mentioned is a pretty good idea.
Once you've got the head removed and you have access to the broken bolts, you have a couple options. If you've got a welder, I would suggest welding a nut to the end of the bolt shank as prevoiusly mentioned. The trick here is that once you weld the nut on, DON'T quench it with water or penetrating fluid. This will make your weld and the bolt hard and brittle, therefore more likely to break off again. You want to let the weld cool on it's own.
If you don't have a welder, try grinding a couple flats on opposing sides of the bolt to aid in the grip of a set of vice grips.
Now that you've got a way to grip the bolt to remove it, try giving the bolt a few good sharp taps with a ball peen hammer. You want to strike it right on the top dead center of the bolt. What you're aiming to do is break the bond formed between the bolt threads and the threaded hole. This helps form a "capillary" for the penetrating fluid to creep down, which is the next step. Spray the bolt down with a good penetrating fluid and let it sit over night. Give it time to do it's job!
Finally, you're ready to try and remove the bolt. Use a propane torch and heat the block around the bolt hole. The idea here is, heat makes things EXPAND. By heating up the block around the bolt, you're enlargening the bolt hole ever so slightly. NEVER heat the bolt! This will actually work against you and make the bolt even tighter in the hole. In fact, do just the opposite. Try to avoid any heat from touching the bolt.
A word of caution must be said when heating aluminum with a torch. If you heat it up too much, you'll actually flow the aluminum and melt it. NOT GOOD.
As you're warming the block up, gently work the bolt loose. When you loosen it a little bit, work it back in the other direction. TAKE YOUR TIME. Keep working the bolt back and forth until you've got the bolt entirely out.
I've personally never had any luck a set of easy-outs. In fact, I think they're a waste of time. On the other hand, a set of left handed drill bits can work to your advantage. Sometimes you'll get lucky and have the drill bit catch the bolt and walk it out for you. Not often, but it happens.
In the worst case scenario, you can always drill the bolt out, retap the hole a size larger as previously mentioned in this thread and heli-coil it. It will hold every bit as good as if the repair had never been done.
Sorry if this all seems a bit long winded. Just trying to help.
