broken bolt extractor

[dragoonmc]

So I changed my sparkplugs a while back and almost broke 2 bolts tightening down the coils.
well yesterday I double checked they were all tight and broke one off in the head. So I grabbed a screw extractor and drill bit and got the screw extractor in and then it broke.
I spent probably 2 hours trying to drill a hole for the bigger (correct) size screw extractor but that just wasn't working with how much harder the broken extractor was. I eventually ended up getting out the dremel and grinding the hole back centered and then grabbed a carbide tipped drill bit intended for glass. This ate right through the extractor and got me a nice hole for the correct screw extractor to bite into and the bolt came right out.

So lesson is use a carbide tipped bit if you break a screw extractor in a bolt.

[WeeYari]

So I changed my sparkplugs a while back and almost broke 2 bolts tightening down the coils.

WTH? How tight did you think they had to be? Those should be barely past snug.

Lesson learned is use proper torque amounts for bolt/application.

[CoryM]

I'm surprised that you were able to cut the broken extractor with a drill bit. Usually it's game over at that point. Did it actually drill a hole into the extractor or just kind of break it?