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I have Denso Iridium IK 24's. Put about 6000 miles on them. My car is SC. When cleaning them last night, I found that all but one has this dark tan ring around were it go's into the bolt part that holds it in the head of my motor. Starting from the front to the back 1st. wasn't bad but the 2nd. and 3rd. were real dark and the 4th. was fine? Do I need new plugs? Why do they have these rings and why doesn't the 4th. have a ring? Thanks for any help.
From your description, and without pictures, it is hard to tell where this ring is. Is it around the plug on the INSIDE of the combustion chamber, or the OUTSIDE.
gernby, It is on the outside. NOT in the combustion chamber. I don't know how to post pics. It's on the white porcelain by the bottom were it screws in. Does that help?
Originally Posted by S2000RAT,Aug 25 2004, 11:33 AM
It's on the white porcelain by the bottom were it screws in.
My spark plugs have the same discoloration on them. I don't know if it's a cause for concern, all I do know is that my car runs fine and the electrodes look fine with good color around the tip.
I have seen the same thing on a lot of direct drive coiled plugs - I think the very high voltages may cause a slight plasma/ozone effect of the rubber and porcelain. It is purely cosmetic IMO and should cause no concern. It is the condition of the anode/cathode that counts. The variance might represent air flow patterns that either reinforce or attenuate the aformentioned comments.
My Cobra has IK-20's, and they look the same as the S2000's plugs in terms of the "brown ring",* so while that is not scientific proof and you know I hate anecdotes, it sure is a big coincidence for two so different engines and cars.
*Of course, it could just mean that I am an a-hole and the car is reminding me of my sad fate.
They probably look like this? ......................................
It might be a bad angle but it shows the brown on the white ceramic part where it goes into the steel part. The left one was in the car for about 25K miles, the middle one was in the car for about 3K miles. The right one is brand new.
(Disregard the rust buildup on the tip. These plugs have been sitting on my work bench for many, many months. They didn't come out of the car looking like that.)
08-25-2004, 06:32 AM
Dark ring around spark plugs?
