How do I remove a broken spark plug?

[David T]

Well you lucked out. Was it the correct adapter in the first place? Why did it break off and get stuck? Make sure it did not damage the threads in the head. Run a thread chaser or a tap to make sure.

[Farrar]

I fault the design of the tube that came with the compression tester - it was screwed together rather than being one solid piece. (Since the tube is now broken, I will use the hose instead.) It didn't take much to remove the thing, which means it wasn't badly stuck in the first place, and in my opinion the tool was poorly designed to have a weak point so close to the end.

The threads are fine - I gently put the spark plug in and took it back out by hand and it was as smooth as silk. Cleaned the threads and then reinstalled with fresh anti-seize. Moving on to the next project now.

[opethmike]

Please let me know what the compression numbers are once you've done the test.

[Farrar]

Please let me know what the compression numbers are once you've done the test.

Will do. Might be another week or so.

[Ron]

So don’t run the motor then. But find a way to heat the head up. Heat makes things much easier to remove.

FWIW, spark plug manufacturers and shop manuals all have warnings to let aluminum heads cool before removing the plugs...

[dn010]

FWIW, spark plug manufacturers and shop manuals all have warnings to let aluminum heads cool before removing the plugs...

Understood, but the situation here is trying to remove a stuck object. Running the engine with the cylinder dead won’t make the steel object expand like a spark plug that is firing.

Regardless, congratulations on getting it out. Now, onto the next problem.