Stationary Engine List

| January/February 2000

Stationary Engine

When a member of this list sends an e-mail to, it is then relayed to over 300 other participants in the group. Each month a lady from England and a barefooted Texan pick a few of the more pertinent and interesting stories to pass on to the readership of GEM. This month, the original question came from Australia, the advice came from around the world, then we also had the verdict on several of the methods suggested.

First, the original question:

I have a bit of a problem with steel studs. The thread is frozen with rust in a cast iron exhaust manifold, and despite the application of the oxy torch and penetrating oil they still refuse to come out. The studs are rusted down to about half their original diameter, so I cannot give them a good twist. They are in blind holes so I don't want to chew them up, as it will require the removal of the complete block (approximately 1 ton) to drill them out. Any ideas will be most appreciated.

The suggestions:

Swap the oxy-torch tip for a cutting torch and burn them out. An oxyacetylene cutting torch doesn't cut cast iron. This technique demands that the cut be made fast because if the cast gets too hot the top edge of the threads will melt. I find that it helps to drill out as much as possible, then use the cutting torch to make fast work of what remains. A quick run through with a tap will remove any leftover slag and bits of uncut thread. Practice on a junked engine in order to build up your confidence and courage.

Drill as best you can in center of broken stud. Ease hole out to where you're just short of cutting into thread. Pick a sliver of the old stud from the threads and try to peel it out. This might give a start thread for a tap (bottoming type), but it's gotta be straight. Gradually take the tap in, just a few degrees at a time, then reverse to clear swarf. Use lots of fluid, go real easy, try to dig swarf out from bottom of hole. This worked for me, but the important thing would be to not go too far without clearing the thread, otherwise you might bust the hole out due to excess pressure.