What would cause spark plugs to become like this?

enargins
Fri, 21 Jun 2024 02:19:19 +0000
Maintenance/Repairs

I had my spark plugs changed today. The old ones were FILTHY, and one was even cracked, even though they only had 7500 miles on them (see photo)! Also, the gap in three of them were wider than in the other two (the mechanic who removed them couldn’t find the sixth one).

I’m curious what would have caused them to become like that. (The old ones were Champion Double Platinum.)

A couple of thoughts.

First, I had my catalytic converter replaced last year, as it was clogged. But I rode around with a P0420 code for a year or more before replacing it.

Also, valve cover gaskets were replaced at the same time, and they had been leaking for several years before that.

So I suppose one of those might have caused it? Just curious.

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