Don't-Strip-or-Break-It
 

Don’t you hate the sinking feeling you get when you realize you have stripped a bolt or broken the head off a fastener. The car project, whatever it was, suddenly got harder and less fun.

Near the top of the Don't-strip-or-break-it list are spark plugs. Nobody wants damaged threads in a cylinder head or half a spark plug frozen in place. Unfortunately, the potential for problems increases when high mileage spark plugs are left untouched in relatively soft aluminum cylinder heads.

Watch Pat Goss's hands-on tips for removing spark plugs without breaking them. Hopefully you will learn a few things that will keep the next spark plug change fun, not nerve wracking.

Removing Spark Plugs from Aluminum Cylinder Heads - YouTube

Listed under Extras and some specific car models, RockAuto has spark plug non-foulers and spark plug hole chaser tools that can clean up damaged threads. There are even tools specifically designed to remove broken spark plugs and bits of spark plug porcelain from the Ford Triton engines.