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Today, for want of something better to do I decided to pull the plugs from my 27 month old S2000 with 20k miles on the clock.
I was surprised to say the least when I removed the plugs to find oil on the threads, oil pooling at the top of the sparkplug holes, a burnt black plug base with very white lean looking electrodes and oil on the plug ceramic.
The pictures of these are below:
Top of plug showing black plug base and pale electrodes
Side of plug showing oil on threads and burnt oil at base of ceramic
Plughole showing oil pooling at base of plug hole
My first reaction is that I have an oil leak but I can't seem to work out from where. But if it is an oil leak then why all four cylinders and not just one?, or two?, or three??
My vehicle seems to perform as well as ever and I have no noticeable problems, however, I am worried about the leaks and what seems to be a very lean mixture (I assumed this is due to the LEV characteristics of the engine).
Has anyone else had similar experiences? Do I have anything to worry about or is this normal?
The photos are not enough to read the plugs.. there is normally carbon build-up around the base.. the electrode deposits do look light but it may be the pic.
The black on the threads is probably cooked anti-seize and should be considered normal on this car.
Assuming the plug tubes are intact the only source for oil around the plugs is from the top. Someone spilled oil or the fill cap was missing for awhile.
Originally posted by cdelena The photos are not enough to read the plugs.. there is normally carbon build-up around the base.. the electrode deposits do look light but it may be the pic.
The black on the threads is probably cooked anti-seize and should be considered normal on this car.
Assuming the plug tubes are intact the only source for oil around the plugs is from the top. Someone spilled oil or the fill cap was missing for awhile.
All reasonable assumptions. The oil may also be a valve cover leak. I'd check torque first, then sealing.
How do these plugs compare with what others have found?
The carbon on the base is normal, as is the white ashy electrode. All a sign of a normal, healthy Honda.
The oil pooling is unfortunately normal, too, though in varying degrees. Have you ever had the valve cover off? Honda recommends using Hondabond on the gaskets, something I find Honda doesn't always do at the factory. The oil leaking is miniscule (you won't see it on the dipstick) and isn't to be seriously worried about. The next time the valve cover is off (valve adjustment), be sure to replace the gasket and the 4 donuts around the plugs.
If you're really concerned, just make a quick compression check of #1 and #4 cylinders. Compression checks are very easy to do. Thread the gauge in the spark plug hole with all the plugs removed and roll the motor over for about 2 seconds. Check each cylinder and they should be within 15% of each other. If one cylinder is signifintly lower than the rest than you may have a problem.
Doesn't sound like it at all. Sounds like initial oil accumulation from the first 5k miles. Especially the baked on brown around the electrode.
Doing a plug check/chop is another way of checking. Run the car up to about 3/4 throttle in second, push in the clutch and turn off the key and coast to a stop. Pull the plugs and you will get a true reading of color. If it's running rich it will be dark brown around the base of the electrode. If it's almost white it's running to lean. If it a medium brown to dark your cool! It will also tell you if your firing on all four. They should all be dry and not wet. If they are wet you didn't chop the ignition at the same time you pushed in the clutch. If you get black soot or oil on the insulator you've got some blowby problems.
Thanks guys, very useful feedback. I didn't appreciate that Honda used anti-seize when inserting the plugs - that certainly explains the oil on the threads (Lucky I didn't wipe it off). I suspect the remainder of the oil could be anti-seize too as there ain't a lot of it. Certainly there is no evidence of oil having entered from above - this is the first time the plug cover has been cracked open and boy were those allen bolts tight!
I had the same suspicions that the valve cover may be leaking but there is no evidence elsewhere to indicate this is so and I would be surprised if it was leaking around ALL four plugholes. The cover has never been off but I will ensure the o-rings are replaced when it is removed.
Re the colour of the electrodes/insluator - yes it is lighter than I thought it should be but it is not totally "bleached skeleton white" so it is probably OK - it's hard to get good photos as I get so much flash bounceback in macro mode. I am generally used to seeing some brownish deposits on the insulator but in this case it was more greyish than brown - that's what threw me.
No guys, you have to look at the base of the insulator. Not the entire insulator. It requires a good flashlight and magnifying glass. Generally the extended part of the insulator is always bleached white. You have to turn it upside down and look all the way down at the base that in the metal body. I'm sorry I should have been more specific.
Oil on Sparkplugs
