OK, it's all over now. I decided that if the broken bolt was gonna cause me to have to replace the exhaust manifold so be it. I wanted that bolt out because I want an EGT port and I didn't see any way to get one that wouldn't require the heat shield to come off the manifold which would be about the same as replacing the manifold. So, I ordered a 7.5MM mangled bolt socket. It was 1/4 drive but that was all I could find in 7.5 MM. Put the socket on a step up to 3/8 dtive and than a 12 inch 3/8 drive extension, Slid the socket on to the bolt and gave it a couple whacks with a hammer. It went on nicely to what was left of the bolt head. I stepped up the 3/8 extension to a 1/2 inch rachet. The socket bit nicely and I felt I could start the bolt if I was a few years younger. Instead I went to a nice power bar, pulled hard and it turned just a bit. I worked slowly and carefully and got the bolt out enough that I could get a good spray of blaster in to it. I took my time and let it cool between efforts. I really felt like I needed something to use to turn the bolt clockwise just a bit but I just couldn't figure out how to do it. Plus, I teared that if I took the socket off I wouldn't be able to get a good grip again. I had pretty much decided that I was willing to die on this hill so I kept after it. And then it broke.Oh well. I removed the two pipes and found that the head had come off and I had about 3/8 of an inch of stud showing. Not enough to double nut, no way to get at it with vice grips. Check mate. I put the pipes back on and took it to the diesel shop. They tried to get the stud but in the end replaced the exhaust manifold, So that is that'

Couple points. If I was younger or poorer I might have put more effort in to getting thsat broken stud out. I have a clamp down adjustable socket that would almost grip the broken stud. I needed some way to get that to bite and maybe I could have gotten it out. I also think I might have been able to cut it off with my dremel and taken a whack with a left handed drill bit or an easy out. But to tell the truth I was tired of messing with it. Besides my tech said that had I done either of those I would have just broken it further down, My tubes and what I could see of the EGR had only very light coatings of soot. They looked very good. Truck is at 75,000 and has never had fuel without Diesel Kleen. I also avoid bio as much as I can. The sheet metal block off that I fashioned was just like it was when I put it on there. I couldn't tell that the sealant had done much but there were no sings of leaks. It was only in there for a couple thousand miles but I think it would have lasted indefinately. And so, that ends the saga of the two bolts. Hope this helps someone.

 

There is a special kit for drilling out broke bolts on that spot some techs use. It's pricey but if your in the business of dealing with 6.7 's it's worth it. Being this is typical one should invest in that kit if dealing with those bolts.https://www.freedomracing.com/csb-00...8aAgevEALw_wcB

 

glad it over but I said many posts back just take it to a diesel shop that does these all the time,they know all the tricks. I dropped my truck off in morning and had it early afternoon. They did the whole delete,muffler,egr etc. 400 labor. Well worth it to me. The bolts were the reason I had them do it. If I snapped mine I woukdve spent more on tools to get them out and a whole lot of agrivation.

 

Well yes and in hindsight I should have done that. But what about the joy that comes with doing a job by yourself. Like I said above, I really enjoy working on machinery. I have done it since my early teen years and just couldn't get my head around sending the truck to a shop to have two 8MM bolts removed, But there is some more I want to add in case some one comes upon this doing research.

When I had the truck in my home shop with the head of the bolt broken off I still had about 3/8ths of an inch of bolt showing. I removed the rest of the bolts and removed both tubes. That gave me a lot more room to work. I was however being very careful. As the truck sat I knew I could reinstall the tubes and drive to the diesel shop. There was enough stud left that putting in the other bolt plus the two on the other end would secure the pipe well enough for the trip. I felt that if I broke the rest of that headless bolt off I would have a giant exhaust leak if I tried driving the truck. I didn't know what that would cause but wasn;t interested in finding out, nor was I interested in calling a wrecker. So I kind of ***** footed around and ended up not getting the rest of the bolt out.

When the shop was done I asked for the old manifold so I could play with it and maybe learn something. It's been sitting on my work bench since while I did some work on my other toy. Today I put the manifold in the vise and locked it down. I did what I was afraid to do before I took it to the shop. I took a 5MM 1/4th drive socket and hammered it on to the broken stud as far as it would go which was flush to the manifold. I blasted it and slowly turned it out. It started turning. I worked on it slowly and was able to do what I couldn't with the mangled bolt socket before I broke the head off. I was able to reverse the rachet shoot some blaster in and then tighten a turn or so. I worked it out in maybe 30 minutes. So, the bad news is I wasted a thousand smackolas, the good news is I have a spare exhaust manifold. Clearly, had I been just a bit bolder in removing that stud I would have gotten it out, and not needed the shop. AARRRAAAGH

Another point of interest is sourcing the EGT, I am very confident that had I just left the two bolts alone and left the pipe blocked at the EGR end it would have worked fine. As it turns out the EGT sensor I have monitored since the truck was new was sensor one on the Edge CTS which was located just aft of the down pipe pre DOC. I could have easily had an exhaust shop weld me a bung on my down pipe and used that as an EGT source. It would not be as accurate as using the exhaust manifold but it is what I've been using for six years.

I hope this helps someone and thanks to all who added to the thread. EDIT Above I used a term often used as a substitute for a house cat. As in _____footing. Or walking lightly. The software censored it. Wow,