In the 50s when I worked at a gas station, plugs lasted for 5000 miles and you cleaned and re-gapped them and charged the customers 25 cents a plug. I think tpday cleaning and re-gapping them today would still get you the extra 5000 miles. I used to go the extra step and file the end of the side electrode nice and square for sharp edges. New plugs were $1.25. and were replaced every 10000 miles.
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As difficult as it is to remove and replace plugs on some modern vehicles trying to clean them does not make sense.
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Why doesnt it make sense?
The steel bristles of the brush are softer than ceramic. Steel will pollute the ceramic insulator. Spark plug cleaners are small media blasters. Doesn’t make economic sense for anyone anymore to clean plugs. The labor involved is high and they may only last short time after cleaning. Yours look used up to me.
The plug in the pic doesn’t look that good to me. Considering that most plugs are comparatively cheap I don’t understand why anyone would bother cleaning them; especially one that looked like the plug in the pic.
Those are plain copper core so 2 bucks each. With plugs out I always run a compression as mentioned by db4690. That gives you an idea of where you’re at mechanically with the engine top end. If it shows a problem then you have a heads-up on planning your next move; whether it be engine repair or dumping the car.
Cleaning dirty plugs in a pinch probably works ok if you do it correctly, but I’ve never done it. I just changed the plugs in my Corolla today in fact. $2.25 each. I get 2 years of operation out of a set, so there’s not much economic motivation for me to clean the old ones. Not enough bang for the buck to take the risk. And there’s the practicality, when you re-install a used spark plug you are supposed to install a new crush washer to insure an air-tight seal, and it is nearly impossible to buy those crush washers separate from the plugs. I label the cylinder number on the plugs I remove and keep them for future reference, in case a problem in one specific cylinder develops, I can check if that plug is a little bit different than the others.
fyi, I mentioned above that I hadn’t seen that gold color on the electrode before on used plugs. I have to take that comment back, b/c all four of the plugs that came out of my Corolla today had a similar gold color on the J–shaped electrode. Not sure what that is, probably some additive in the gasoline.
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