Homemade sparkplug thread chaser

It was a real bear to remove the plugs this time & the threads were a little messed up. The car was apart & the wife was out with the other one, the weather was too nasty to ride my bicycle to the parts store, so I broached a groove into an old sparkplug to give it a cutting edge & a relief pocket to collect any chips & debris, Ref. Photo. I used "Tapmatic" for aluminum, threading fluid & screwed the plug all the way in. After removing, there were a few small flakes of aluminum in the pocket but I doubt if much if any got pushed into the cylinder, but just in case, I made a rubber hose extension on my air nozzle & gave each cylinder a quick blast from the inside. What few small chips might remain, will get blown out of the exhaust quickly so I'm not too concerned about it. This time I put a little anti-seize on the new plugs. I've heard lead-base anti-seize can foul the O2 sensor, so I left the first 2 or 3 threads dry.

I put a sparkplug tap on my list of things to get next time I go for parts, a little grease in the flutes works nicely to catch chips. If going to the next extreme & installing Helicoils, one could position the crank on that cylinder at bottom-dead-center as the exhaust valve is opening, & duct tape an air hose at about 20 psi to the tailpipe to blow any chips back out the sparkplug hole.

gale, 92 735i

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