Hi to all of you. I'm new to the forum but a long time Pontiac fan.
There is a simple solution to this. Some of you are close but not quite there. I have a cylinder head repair shop and this is how I remove broken exhaust bolts.
Weld a nut to the broken bolt with a wire feed welder. Insert the electrode wire into the hole of the nut and completely fill the hole with weld. The nut will be glowing bright orange at this point and so will the bolt inside the cast iron. The cast iron acts like a heat sink and does not get as hot. The rust also acts somewhat as an insulator. As both the bolt and the manifold cool the bolt shrinks more than the manifold.
Once it has cooled the bolt will screw right out with a wrench 95% of the time. I have had to weld on nuts 2-3 times on especially stuburn bolts.
Center the nut as best you can but the weld does not stick to the cast iron so it is unlikely you can weld the nut to the manifold even if it is broken off below the surface.
Bill
|