I found the following technique quite useful for removing exhaust manifold studs on my 2G (after a bit of trial and error, of course ;))
- 2 of the 12mm nuts that you removed to get the manifold off.
- 2 of the 14mm nuts that you ...
- 12mm and 14mm closed end wrenches
- 12mm and 14mm sockets or a second pair of 12mm and 14mm closed end wrenches
- PB Blaster penetrating oil or similar
- Hammer (maybe)
Here's how it goes:
- Use the PB Blaster in advance. Spray it at the base of each stud.
- Hang the closed end of the wrench around the stud so that it angles away from the engine.
- Screw one of the nuts on backward and the second nut on forward (so that the flares mate to each other). Use the 14mm nuts on the two end studs and the 12mm nuts for the rest. Screw them on enough so that a few threads of the end of the stud are exposed beyond the second nut, but leave enough room for the head of the wrench between the inner nut and the head. The picture shows this.
- Now get the socket/ratchet on the outer nut and slip the closed end of the wrench onto the inner nut.
- Tighten the nuts into each other. Take a look a this picture.
If you position the tools this way, you can grab both the wrench and ratchet with both hands and squeeze them together to really torque them together without busting your knuckles. Don't torque them together too hard, though, or you might strip the threads. The lock nuts will "click" as the ridges on the mating surfaces of the nuts slip by each other. Using the closed end and socket was the trick. The open end will flex and can round off the outside of the nut, but the closed end and socket will not.
- Remove the socket and try to loosen the stud (couterclockwise) with the wrench. Since you left enough room between the inner nut and the head, you can slide the wrench off of the nut and reposition the wrench to get the best angle. If the nuts turn but the stud doesn't, repeat the previous step, but just torque the nuts together a bit more (maybe one more "click"). For the more stubborn studs, blast 'em with more PB Blaster and give it time to penetrate. Also, you can take a hammer and LIGHTLY tap the end of the stud. Repeat this until the stud turns.
- Once the stud has broken loose, slip the wrench off of the inner nut and use the socket on the outer nut to back out the stud. You'll get your wrench back when the stud is off ;).
I did this for each stud and got them out no problem (some were harder than others, but they all came out without rounding off a nut, stripping threads, or wracking my knuckes ;).
If you can't break the stud loose, you can separate the jamb nuts, screw them off, and get your wrench back. Then you can try something else.