Ok... we all get to chasing a rabbit hole and often the info/ tool/ part isn’t needed. So:
NEVER TRY CLEANING A GLOW OR SPARK PLUG HOLE YOU DO NOT HAVE TO. the odds are WAY against you. Statistically you are going to do more damage than good. This is a repair only done when needed.
This is probably the case here. If after you break the glow plug free and use the socket to go 2 full revolutions you can remove the plug by hand- you don’t need to do anything else.
If the threads are rusty enough you have to use the ratchet the whole way out- then you do need to clean up the threads.
Always start with the bottle brush technique first. Don’t spray anything down the hole. Spray wd40 or whatever you are using as a penetrating oil onto the brush which hopefully you have a little cordless drill that can hold it, otherwise your forearms will be tired when done. You want the outside diameter of the brush same size as the glow plug ir slightly smaller if possible. Push the brush in and try running it in reverse the whole time if possible. That will have the brush pushing the garbage out the threads instead of into the block. Don’t think the drill needs 2,000 rpm That just flings wd40 everywhere, slow speed is fine. 20 seconds and pull it out, spray more wd40 on the brush and do it again.
With a non-rusty glowplug, try hand threading it in. When it goes in all the way by hand, you are done. A trick to hand threading in or starting a glowplug or spark plug and not cross threading or just simply getting it to start in hard to reach angles: slip a 6” to 12” piece of vacuum hose on the end where the socket goes. I can’t believe how many of these Mac Tools spark plug starters I sold when I was the tool guy. Ift guilty and told everyone “you know you can just use a piece of vacuum hose, right?” 90% still bought the thing for $14.99 instead of $2 worth of hose. (See pic)
Back to the rabbit hole- lets go deeper and this time take a left at Albuquerque in honor of buggs bunny..
What if yours are so rusty you had to use a propane torch to heat the glow plug enoung to remove it? The bottle brush (brass is best) didn’t get the job done after 5 minutes of drill spinning. Then you still should not use a regular thread chaser and NEVER A NORMAL TAP!!! This is where this tool comes into play. It’s pricey and you use it once, then it sits forever in the bottom of the tool box, Then 20 years later you sell it later for $5 at a yard sale. Look close at the threads. They collapse and expand. You spray wd40 on it, collapse them, slip in the hole, expand them and unscrew it from the hole. Rinse with wd40 and do it again. Then go back to the brush 1 time only for a couple seconds. Then try the glow plug by hand, preferably with you $18,000 mac tools chunk of rubber hose. Haha
How often this tool is actually needed? Almost never. If it is zombie day and I could not get this tool, but really needed to- can you use a normal thread chaser- yup. But I would supply shop air into the intake manifold so it is blowing out the glow plug hole non stop while i used it.
Remember you are removing metal/ rust and whatever you don’t get out that hole- is going straight down the cylinder walls scratching it up and throwing your compression out the window. Think how picky you would be if a new engine had a single scratch going vertically in the cylinder wall. And you are about to add maybe 40 scratches before that part gets ejected. Remember how ai started.
NEVER TRY CLEANING A GLOW OR SPARK PLUG HOLE YOU DO NOT HAVE TO.

