writes:

plug will loosen slightly. More effective than the loosening will be
the relaxing of the grip of the teflon dope. I used to rebuild air
compressors that often had steel plugs in aluminum, and we used to
torch just the plug, let it sit, then back it out. The biggest risk
with this was the tearing out of the aluminum threads, especially with
the softer casting aluminums.

Here's another approach:

Get a sacrificial Allen key.

Put it in place. Have plier handy & H2O.

Heat the key with a torch. Done right, that will heat the plug
without torch spray hitting the case.

Monitor the case temp but you should see the dope smoking.

Pull the ruined Allen wrench; quench in H2O to avoid starting
a fire. Then, ASAP, use dry ice on the plug. And/Or use the
hand impact tool CAREFULLY.


That said, there have been times I haven't been able to get
plugs or other fittings out of the engine core when installing a new
one, and rather than risk damaging the core ($$$) we put in a new
fitting and let Lycoming fuss with getting the old one out.

I hate steel plugs in Al bodies. I don't know what should be
used there, but that's not it.

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433