drilling out exhaust manifold bolts on '83 280zx

[wickman10]

Help! I got the exhaust manifold off and was trying to get the two end bolts out, they were sheared off, which seems to be a common problem with them. I broke off an easy out in one of them and the other the drill hole got off center. I seem to be making a mess of things. Any advice as to what I can do now. The more I drill the more it wallows out all around the remaining bolts and tears up the aluminum and I can't keep the drill bit from walking. Can I get by with replacing the gasket and not worrying about these outside bolts? If not, any suggestions on what to do about fixing these outside bolts?

[bobc]

Brian,

If it makes you feel any better, I just went through pretty much the same process with a stud broken off in my cylinder head. Once, you get an easy out broken off in the nut, you're pretty much done trying to drill it out. The easy out is just too hard for the bit to catch and you'll just wallow all over the place (my experience and confirmed by others)

I had the stud removed using a metal disentegrator process. It basically melts the nut without damaging the threads. It worked, but it wasn't cheap. $200! See info below:

"Electro Arc's metal disintegrators are primarily used for removing broken taps, drill bits, screws, broken bolt removal, stud remover, dowel pins, and many other types of fasteners. There is no distortion to the part, hole or thread. Core sampling is accomplished quickly without distorting existing material properties. This process is also known as electrical discharge machining and spark erosion for tap removal, stud removers, broken off bolt extractor, and the removal of other tools. Electro Arc electrode metal disintegrators are also used for roll marking and branding metal for permanent identification."

You can also try to weld a rod onto the broken off piece (again, the easy off is going to complicate the weld) and use the welded on piece to try to back it out.

Good luck!

Bob

[dodgermike]

I also had a similar situation with one stud broken off in the head and another bolt broke off with about half an inch sticking out of the head. I'm in the process of restoring this car, and am installing a header, and in the process I went ahead and removed the carbs and intake in one piece so that I have easy access to the face of the head. After cleaning the bolt that was protruding from the head, I then proceeded to weld a half inch nut onto the end of the stud, and then used a battery powered impact gun to back the bolt out of the head. For the stud that was broken off in the head, using a mig welder, again I cleaned the face of the stud as best I could, and then built up a beed until I had enough beed outside the head that I could again weld a nut to. Using the impact gun, I again backed out the broken stud. The heat from welding aids in the loosening of rust and corrosion. I was surprised actually to find how easy these studs came out. Hopefully you have the use of, or a friend who has, a mig welder that you can use to do this. It doesn't cost nearly as much as desintegrating a broken stud. If you don't have access to a welder, you can remove the head and bring it to a welding shop that would be able to do this. I'm sure it still would not cost as much as desintegrating.

Good Luck,

Mike

[beandip]

wickman, Since it has been 18 days since your origional posting . I would be surprised if you haven't fixed this. I have tried easy outs in the past many times . For me they are about a 50 , 50 chance of success. Any more if I snap off a stud and cannot remove it with out using one, I take it to a pro . I don't have access to a welder . I will use a eZ out only when it is on something other than the engine. For me they are a last resort. I replaced all the manifold bolts with studs , this way I can use Krol or Blaster with better success.

Gary

Edited January 18, 2009 by beandip