broken studs help?

[911-m5]

I was going to put on new heat exchangers this weekend. One of the studs broke off flush. Is there any other way to get it out besides drilling?

thanks
allan

[cstreit]

EDM is another way, certainly no easier though, but safer... If you're going to drill, be VERY careful. You don't want to slip and drill into the heads! There are shops (very few) that have an EDM machine that can get to this wih the car on a lift... I've only seen it in pictures though.

I would probably try drilling myself, but it's such a small stud that the screw extractor could break off as well, then you're in deep. If you're going to try this, soak it for days with a good penetrant like PB Blaster. Make sure you use a good sharp punch to seta dimple in the stud end for the drill bit. THe shock of the punch will have the added benefit of possibly loosening the stud a bit.

Just drill slowly and carefully. Drill bits are cheaper than heads. Time taken here is cheaper than having to remove a head...

[Superman]

Yeah, if you're gonn a drill, get some patience. Drill right in the CENTER. Use a reverse bit. Then a larger reverse bit. Drill really straight and in the center and deep. Take lots of breaks. Use penetrant. Take days.

[cstreit]

"The Man of Steel" makes a good point, a reverse drill bit might help coax it out as well... If you're going off center, stop.

Really take your time.

[HawgRyder]

Did I not see a post on this just recently....someone had made a jig to keep the drill on centre?
Seemed like a great idea at the time....a jig which fitted the other stud and perhaps the exhaust hole at the same time...with a hardened collet to hold the drill bit at the correct point and at a 90deg angle.
Bob

[ChrisBennet]

I know everyone likes to do thing themselves but sometimes it makes sense to let a pro do some things. I mechanic friend of mine has probably drilled out hundreds of these on 911's. If I had to remove some heat exchangers or drill out some studs I would pay him to do it. I've got a few engine rebuilds under my belt but "A man's got to know his limitations."
-Chris

[Superman]

This is indeed a job that might be best for a pro. JW has a jig that does bolt to the other stud and centers on the exhaust port. If you do try it at home, did I mention the importance of going slowly and making sure the bit is centered and perfectly parallel with the stud? Did I mention patience and taking your time? Penetrant? Reverse drill bit? Reverse bits work for me. Half the time, the fastener comes out without having to use the screw extractor. The best screw extractors I have used are the Snap-On ones. Reasonable. A set of five for around $30. I would not use an extractor besides these.

[john walker's workshop]

properly removing a broken off stud, that is frozen besides, is harder than it appears. the absolute key to success is first drilling a small pilot hole DEAD CENTER all the way thru. only with a drilling jig can the whole stud be drilled out with a large bit on the first pass. if you drill it out dead center, with the right bit, the threads will remain and can be pulled out like a helicoil. with timeserts, the stud is drilled out threads and all.