Oh, boy! I was cruising right along last night, en route to removing the camshafts on my 968, when I stripped not one, but two XZN (Cheesehead) bolts on the camshaft bridge support. I am including two pictures so that you all can see exactly what I'm up against. What do you think would be the best method for extracting these bolts.

Your thoughts and suggestions are appreciated.

Note: I have already tried bolt-outs and screw-outs. Sadly, the screw-out broke off in one of the bolts!

 

Drill the head off and remove the stud with vice grips.

 

Thanks for your quick response.

I have already used vise grips on the head of the bolt, to no avail. Do you think if I were to drill the head off that the vise grips would then be able to do the trick? Since the vise grips did not work on the head, it doesn't seem that they would work with the head drilled off. Knowing that I have already tried using vise grips, do you still think that drilling the head off would help?

 

Does that bridge support pull up and off the bolts? In other words you don't have to slide it off 90 degrees to the bolts. If it pulls up then just drill the triple square heads off. Pick a drill bit a few thousandsth undersized so you don't drill too much into the bridge support holes. The head will snap off onto the drill bit once you get once you get a little past the shoulder of the head. Pull the support off and as long as they didn't use loctite on the threads you may be able to unscrew by hand but a vise grips on the remaining stud should do it if there is corrosion.

This is a very common problem on the triple squares that hold the pressure plate to flywheel on the 924/944 and the above works pretty slick. Although those are a steel bolt and steel flywheel, you have steel to aluminum on this problem so you may have some electrolitic action which will require the vise grips.

Edit: Yes drill the head off so you relieve the tension on the threads and then they should come out pretty easy. On my pressure plate I unscrewed the remaining bolts with just my fingers.

 

I see now! Gotcha! I think wrestling with this problem until 3:00 in the morning and then sleeping for only 4 hours before getting up for church service has caused a few neurons to cease from firing. I am going to take a nap now and tackle this problem tonight.

Will high speed steel be sufficient for drilling off the head or do you think I will need to go with carbide (or carbide-tipped)?

Thanks very much!

 

Yeah, and DON'T use easy-outs, especially when this little trick will work.

When I drilled out my pressure plate bolts, I just used a "normal" drill bit without any problems. I wouldn't think that bolt is made of anything very tough to drill through.

 

if its still tight and vice grips won teven do it (after the head is off) use a pipe wrench on the stud, better than vice grips in a lot of cases., IMO

 

Yeah, any 'ole drill bit will work just fine as those bolts aren't hardened or anthing exotic. Just make sure you have a good sharp tip, not something you have trashed drilling concrete, and come at what is left of the triple square hole straight and square so you don't wander off and drill into the bridge metal.

When you get close to drilling through the head, the drill will catch the head and snap it free. Then just work the head off the drill bit and start on the next one.

 

I would try a pipe wrench before drilling it out.

 

Wait, did you edit your first post to say that an "easy out" snapped off inside the triple square on one of the bolts? That is a problem. Easy Outs should be banned friom the face of the planet.

Easy outs are tool steel and about impossible to drill out cleanly. I don't care what type of drill bit you use, it will be a problem doing it by hand. One reason the fancy plasma burners were invented. How to get this clipped off at surface level on a cheap and reliable basis with motor in the car? I would get a small stone or diamond wheel to grind the head off. Dremmel should have some consumer wheel that would work and be cheap. Well at least relatively cheap. You can crack the tool steel with a punch but that can result in other damage so I wouldn't try that as a first option.

Stone will kick tool steel's butt, not many other reasonable options in your case.

 

I snapped one off in one of the PP bolts, before I realized I could just drill the head out. Took a good 4 hours, and probably 40 drill bits to get through. Easy outs are anything but.

Good luck with that. I'd try a pipe wrench before trying to drill it out.

 

ahh, the lovely cheeseheads. i drilled out no less than 7 of the 20 cheesehead bolts in there. replaced them with allen-head bolts of the same length and pitch that i got at ace hardware.

if you drill them out, be VERY careful about the metal shavings. in fact, i would go so far as to remove the head and clean it thoroughly so you don't get metal shavings in the engine.

 

I've had luck by drilling a slot in the head with a dremel tool, then chucking a screwdriver bit into one of those hand-held impact drivers that you whack with a hammer.

 

I want to thank all of you for your responses. A special thanks goes out to Iceshark for his thorough posts. I picked up some tools today that will help me with the job: 2 drill bits (one HSS, one carbide-tipped), and a nice pipe wrench. I am going to use the pipe wrench first, and if that doesn't work, I will take to drilling. Joseph, I certainly hope that I don't strip 7 of the 20, but at my current clip (2 for 4), I will strip 10... Hope not! Lizard, your idea is a good one; however, because this camshaft bridge piece is non-replaceable (not in PET), I better pass. In fact, the remaining 16 bolts also attach non-replaceable parts... Wish me luck!

 

snap-on parrot jaw pliars...they put more leverage in the jaw than locked vice grips. they never fail fo rme.