My wife's 86 745T had several broken exhaust studs. I was able to drill and remove all broken studs but one. In order to remove it, I pulled the head and put it in the kitchen oven, at 225 degrees F., for about 45 minutes. When I pulled the head out, it was at about normal operating temperature. The broken stud came out with torque that would not remove it at room temperature. The thermal coefficient of expansion for aluminum is very close to twice that for steel. Now the kitchen smells like an automotive machine shop. It is a good thing that Thanksgiving was three days ago, or I would be out on the street. My wife would never let me fix my car this way, only hers. If you choose to use this method, I don't recommend locally heating the head, as you might warp it.

Last spring I removed the head off my '87 745T due to a broken stud. In my case, the stud broke flush with the head, so there was no way to get a wrench on it. Took the head to a head shop and had the machinist replace all the studs, figuring that if one stud is bad, more were ready to let go.

The machinist trick to removing the remaining studs was amazingly simple and effective. He hooked up the hot side of his welder to the stud, the ground to the block. Set the welder for about 150 amps., then turned the welder on for 2 seconds. The studs after this treatment are hot to the touch, and the head is a bit warm. But the crud in the threads that makes the stud stick is all burned out. It is the crud that is causing the high electrical resistance. Hence, it is the crud that really heats up and burns off. With the curd burned off, he is able to easily unscrew the stud. He finds better than 90% of stuck studs can be removed this way. And there is not warping of the head since the heat is pretty much contained to the cruddy threads and is only applied briefly.

Just one of those welder tricks I have filed away for the day when I get a welder.

A few years back, a thermostat housing stud broke off FLUSH with the aluminum cylinder head on my Datsun. No problem, I thought, here's a chance to use my new Easy-Outs. I drilled a nice hole through the center of the broken stud, inserted the easy out, proceeded to turn the easy-out and... snap, I broke the *%#@!# easy-out off. Having exceeded my mechanical capabilities, I consulted a friend was a mechanic for many years working on all sorts of machinery and equipment. He said "No problem, take off the head and bring it to the shop", which I did. My friend then filled a wash basin with water and put the head in the water with the area of the head containing the broken stud above the water line. He layed a nut on top of, and centered on, the broken stud and then quickly arc welded the nut to the stud from the INSIDE of the nut. Then, a wrench was put to nut and the stud came out easily. I was amazed.

Attaching the ground clamp to the exhaust port casting area would be the best.

That is a great method. Anyone doing this needs to keep in mind where the ground electrode is connected. If the 150 amps of current travels through a valve and seat, or through the valve stem and guide, your troubles have just started. Be sure to place the ground electrode adjacent to the stud being removed (preferably install the ground on another adjacent intact stud), or disassemble the head.

Gary, that trick's gotta be the best this year!

Just one more reason to buy another welder. ("But Honey, the studs, the studs! And it's aluminum, so I need a TIG!")

Don Foster (near Cape Cod, MA)

John, you're right. The coefficient of thermal expansion of aluminum is about twice that of steel, not six as I said. Thanks for pointing that out.

"...kitchen smells like an automotive machine shop..."

And what's wrong with that? Much better than broccoli.....

Don Foster (near Cape Cod, MA)

Or worse yet Cabbage! We have a twin house that is a rental. Our neighbors like to cook cabbage and Ham hocks on the weekend. That is the worst smell I have EVER encountered. I thought the sewer backed up! No Kidding.

And she agrees that it smells much better than it did three years ago when she boiled the turkey soup dry on top of the stove. It smelled just like burnt feathers. It cost the insurance company a couple thousand to fix the smoke damage.

"...thermal coefficient of expansion for aluminum is very close to twice that for steel..."

Six times that of steel, I think. So your approach is very sound.

Don Foster (near Cape Cod, MA)