Does a Buick Template exist that facilitates drilling out broken/sheared exhaust manifold bolts? Appreciate the guidance! Thanks!
Wouldn't be hard to make one from a head gasket, some plate steel, and a hardened bushing. Most guys would just do it freehand.
If you mean the broken bolts through the exhaust manifold into the head, I did make a jig to remove one of those with the engine in the car... I used the exhaust manifold itself and drilled through a plate to make the jig. The hole for the broken fastener I just drilled smaller, and used a bushing as Schurkey said to stay on center. Then I bolted the plate onto the head using the exhaust bolts with sockets to space them, and used a right angle drill adapter to get at the broken one (it was at the left rear). It was a pain, but was successful.
Man O man,you aren’t kidding it’s a pain,Max. It still gives me pain thinking about doing that job on my 67 430 Wildcat convertible while in the car with very limited tools in the school parking lot during my brief attempt at college. Couldn’t make the cut at school but fixed my Buick. Wish you luck though on yours.
I've done more than I care to remember. I'll give you my method. Worst part is gaining the necessary access for a drill. Worst case, you'll need to yank the engine. Im going to assume it's one of the through bolts that go into an ear. First center punch the broken bolt. Don't worry if it's not exactly in the center. Start with a small diameter bit. Maybe 1/8" to start. Drill it as close to center as possible. If your a little off, angle the drill slightly to get to back on center. Once to drill it through, your halfway home. Keep increasing the size of the bit. Again, if the hole gets off center, angle the bit to keep on center. Keep drilling till you get the outer diameter as thin as possible Once you drilled it out as large as possible, you can try two things- if you can, you can take a hammer and chisel and cave in the sides of the bolt. That will make the bolt loose in the hole and you can remove what's left with a needle nose or an easy out. If there is very little remaining, you can try running a tap very carefully in the hole. A little bit at a time, backing the tap out after to clean the tap and hole of debris. Patience is key here. If you rush it, your going to eff it up If you did it right, you can save the original threads.
When I broke exhaust manifold bolts on my Trailblazer six-popper (common problem--GM glues the bolts into place so they don't vibrate loose) I welded nuts to the broken bolts, then turned-out the nuts. One bolt broke above the surface, that one was easy. I hung a nut on the stub, welded it, and turned the bolt out. The other broke below the surface, I had to blob weld into the hole to build-up a post I could hang the nut on, and then weld the nut to the blob, welded to the bolt.
GAH!!! Proper drilling is the pilot hole and then the final size. Bumping through multiple sizes ruins the bits and greatly increases the chances of breaking the bit. This is coming from a guy who used to sell reallllly expensive bits, and watch people wear them out and not know why..
Works for me. And I agree, it's not the best for bits. I'd rather waste a few bits though than screw up a head. Unless the head is fixtured and your using a drill press or a Bridgeport, it's near impossible to center punch it exactly in the center of the bolt and just drill the final size.
That works for bolts in blind holes really well. The issue with a Buick head is there are 4 bolts that go into through holes. The excess threads on the opposite side rust. Even heating them up cherry red doesn't work sometimes. The pitted rust on the opposite side is the issue I had a friend that would blow them out with a torch. He had the technique down with no damage to the head. My luck I would blow the ear off the head.
