go to bunnings, go to the tool section and ask them for one of those tools that remove snapped studs, forget what is called, but it costs like 12 bucks, and get a drill bit too, think its like 6mm u need, costs like 8 bucks, then drill a hole into the stud, stick in the tool and it will slowley bring it out, if that fails, get a 10.25mm drill bit, bore out the hole, tap in a new thread, put in a helicoil thread, then ya new bolt. i had to do it to mine couple weeks ago, easily done, but if its not at the front of the engine u will need to get a right angle converter for your drill, costs liek 15 bucks at bunnings. hope that helps, if not, pay someone 100 bucks to do it for u