Mention the job of removing exhaust manifold bolts to an amateur mechanic and you'll get an involuntary shudder. Heck, many professional mechanics can't utter the phrase "exhaust manifold bolt" without adding a colorful profanity in front of it. While there is no guaranteed, never-fail method or tool to remove every exhaust manifold bolt, there are ways to reduce the ordeal.
In our shop a tool from Blue Point is rapidly gaining popularity. It's part number is PH1050, and for around $55 it allows the user to vibrate a stubborn bolt with an air hammer while applying torque to the head of the bolt with a wrench.
Imagine a shank that fits into an air hammer, with a 3/4" hex section in the center of its shaft, with the opposite end fitted to hold a 1/2" drive impact socket. With an air hammer on one end, an appropriate impact socket on the other end, and a hex section in the middle to allow the user to apply torque with a wrench, many bolts surrender after a few quick "buzzes" with the air hammer. Mechanics in our shop report an 80 percent success rate using this tool to remove exhaust bolts that defied "polite" initial attempts at removal.
What about bolts that defy even the special tool? Well, that's when we break out profanity, a torch, and other vicious, violent tools to win the battle.