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Interesting markings on original spark plugs, thoughts?

xplorre

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Just changed my plugs out at 67000 mi. I do almost exclusively highway driving, was running 87 for most of that time, switched over to 91 in the last 3000 miles or so. Truck was acting fine, but decided I would change them for preventative. They seemed very tight when I took them out, I used a small amount of anti-seize on the replacements, and dielectric on the boot connection.

I'm familiar with Corona staining, but the tracks on these plugs seem different. I read elsewhere that over torqued plugs can cause this type of tracking, when the exhaust leaks passed the crimp inside the plug.

Anybody have experience with this?

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RedlandRanger

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I replaced mine about 40k and had similar (although not quite as bad). Others who've posted photos have shown similar marks. I don't know, but I'd assume it is "normal".
 

got3fords

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If that were escaping gasses, wouldn't the boot show some damage as well? It looks like the boot completely sealed it off from going any further.
 


Big Blue

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Looks kinda cool actually , like the juice is running on the outside too ...
Not far from the actual truth, really. It is called corona staining. Caused by the static charge generated by the plug firing attracting dirt particles to the exposed porcelain of the plug. Completely normal with today's high energy ignition systems.
 

FunInTheSun

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