I have a set of leading plugs I want to clean up and possibly reuse as they only have about 5K on them and I pulled them when I decided to try RX7 plugs instead. These are the new leding plugs that came with the new starter kit.

Any suggestions as to how to clean off the carbon without damaging the plugs? Will carb cleaner work? can I use a metal toothbrush or will that hurt the electrodes?

 

Do NOT use metal brush, it can scratch the insulator and leave traces of metal. This can provide an alternative path for the spark to ground, and quickly lead to mis-fires and carbon-tracking.

If it's a reasonable amount of carbon (i.e. the plugs still fire ok), leave 'em alone. Plugs are self-cleaning in a properly tuned engine. If your engine is running properly and the plugs are the right heat range, they will reach their normal carbon level all by themselves. If the engine's running too rich or the plugs are too cold, they'll get fouled up regardless of how clean they are when you install them. If the plugs are carboned-up and you've since remedied the problem with the engine, the plugs will clean themselves (within reason).

If they're oil-fouled, the carb cleaner will get rid of any oily goo. You can use a wooden toothpick to scrape out any large dry carbon accumulation. There are "spark plug cleaner" gadgets but the ones I tried are more cosmetic than anything else.

If they were misfiring and already developed "carbon tracks", forget it. Carbon tracks are when the spark has found a path to ground over the insulator, and the spark burns a "track" where some of the carbon is fused with the ceramic. There's no way to "clean" carbon tracks; the plug is ruined. Which is what will likely happen if you use a metal brush.

 

you can only clean the metal portion. I use a small screw driver.

These are thin wires not the big metal tab on most cars. Kind of hard to clean the tip with out bending it. then you have to reset the gap.

Oh I use sand paper too. As long as you don't touch the ceramic you'll be fine.

Not much cleaning is needed on new cars nowadays. Not like the old 70's and earlier model cars.

 

buy a small ultrasonic cleaner kit like those used for jewelry etc.

 

I once cleaned out my plugs after i bought new ones just for fun... i used a sandblaster and it worked great, after that a buffing wheel on a jewelry apparatus like Team RX8 said followed by an ultrsound bath....i work in a dental lab..i was having fun. I didnt re use them but by the time i got done with them they looked brand new, I was impressed. A word for the wise though i dont know much about alternative paths of spark to ground but they did look great and i would have probably reused them not knowing any better. Some 1 enlighten me if i did something totaly stupid...

 

Carbon on the metal isn't important; it's the condition of the ceramic insulator that determines whether a plug is fouled or not. The spark will take the path of least resistance. Hopefully, that means jumping across the air gap between the center and side electrodes. If the ceramic is excessively fouled, the spark can find a path through the Carbon that offers less resistance than the air gap. I.e. the resistance of Carbon is less than the ceramic. But the resistance of carbon is never lower than the metal.

 

My mechanic use a sand blaster sort of thing

https://www.rx8club.com/showthread.p...ght=hesitation

With before and after photos

 

Never, ever, EVER use something metalic or abrasive to clean iridium or platinum spark plugs.
Use a solvent and a nylon brush.

Sandpaper? Are you kidding?