Spark Plug Color- Burning Oil

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Greetings-
what color would the spark plug center electrode be for a cylinder that is maybe burning a little oil? Plugs for five cylinders appear light brownish or white, while the number two cylinder has some coarse med gray deposits on the center electrode. Otherwise, the engine runs superbly wo any indication of oil burning. Color charts say this is a normal color, but since it is quite different from the other five, my suspicions are aroused. Or is this just normal BITOG paranoia?
 
Originally Posted By: willbur
Greetings-
what color would the spark plug center electrode be for a cylinder that is maybe burning a little oil? Plugs for five cylinders appear light brownish or white, while the number two cylinder has some coarse med gray deposits on the center electrode. Otherwise, the engine runs superbly wo any indication of oil burning. Color charts say this is a normal color, but since it is quite different from the other five, my suspicions are aroused. Or is this just normal BITOG paranoia?


To properly compare cylinders to one another based upon spark plug appearance you need to make sure that whoever installed the spark plugs last timed them correctly. If they are all rotated exactly the same with respect to the valves and piston then you can make an accurate comparison between cylinders. Otherwise it's a wild goose chase.

If your spark plugs do not align properly when tight then you may need to take them to a machine shop and have them build it back up and then cut new threads that are aligned properly.

Only truly paranoid machine shop owners will take you seriously when you request this procedure;)
 
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I doubt their has ever been an indexed spark plug in an everyday vehicle.
 
Originally Posted By: CT8
I doubt their has ever been an indexed spark plug in an everyday vehicle.


The Honda Insight had indexed plugs from the factory. Was a pain to replace plugs because you had to order them by index number for each cylinder.
 
Originally Posted By: mightymousetech
Originally Posted By: CT8
I doubt their has ever been an indexed spark plug in an everyday vehicle.


The Honda Insight had indexed plugs from the factory. Was a pain to replace plugs because you had to order them by index number for each cylinder.
That is amazing. Squeezing every mpg and ounce of power possible it seems.
 
Originally Posted By: mightymousetech
Originally Posted By: CT8
I doubt their has ever been an indexed spark plug in an everyday vehicle.


The Honda Insight had indexed plugs from the factory. Was a pain to replace plugs because you had to order them by index number for each cylinder.


Lol, I was just making a joke since he was joking about BITOG paranoia. Had no idea such a thing existed.
 
Thanks All for this valuable insight into spark plug indexing. However, will this explain the observed color? Indexing is a very inexpensive means to improve power but is it actually relevant to spark plug color?

So, do med grey center electrode deposits indicate oil burning?
 
Indexing plugs does not require machining since the start of the thread on the plug relative to the ground
electrode position would be random.

Back a few years ago I did consider indexing washers/spacers for plugs in a V8 engine. I originally
was looked at indexing to fix a bad smog test, it made no difference.

With small cylinders in V6s, etc, and fast lean cylinder fuel burn, a plug facing the "wrong way" likely
makes a .01% difference unless your building a race car!
 
Prolly represents the proximity to the PCV system inlet location, or to the most pronounced drafts that waft by the PCV port ... Or you have a minor valve stem seal weep, or you have a very slow intake gasket weep on that port, or something. The color is telling you something, but we don't know what ...

Usually a cylinder burning oil will have a blackish plug ...
 
But to answer OP's question, yes, it may be burning a bit of oil on that cylinder. Don't worry about it, I don't think it is time to start building a new engine yet.
 
I think Broc nailed it with his answer--closed cylinder to PCV 'wind'--Even though EGR also distributes to all cylinders,that particular plug maybe the closest to EGR flow?
Steve
 
Indexing is not needed in 99.9% of vehicles today. With old Pushrod engines in relation to a intake and exhaust valve it helped. Head designs have improved alot and pretty much made this mod obsolete. With like 4 valve cars you have a 50% chance of indexing the plugs randomly anyway in an install. Regardless with technology available to use it's been found indexing doesn't help anymore. Fuel trims from obd and datalogging have shown this.

OP, I changed my plugs a few weeks ago and saw a plug that looked different than what I've seen in my 19 years of car mechanics. If you were the one that installed the plugs you could use the used plugs as a reference. With how PO's treat cars, you have no idea what was a used plug, what was in the car for 5 years vs 6 months. I saw a good chart referencing used plugs. It posted over 25 different pictures of plugs as a good reference. If you pull up a chart with 5-10 used plugs from detonation, fouling, etc it's to generic. Reason being is you don't know if a car was running lean for 4K miles than fixed, than perfect for 1k miles but starting fouling because of excessive pcv pressure from oil through intake or whatever. I know now since my plugs were installed that the car is running perfect on all cylinders from datalogging, maintenance, etc so when I pull my plugs for inspection I can than evaluate how the engine was running. The plugs tell some of the story but only part of it. You could pull a plug that looks like the car was running rich as [censored]. In a OBD2 car that meant the car was running lean a [censored] as the ecu was compensating by dumping fuel. If you want to really see how your engine is download torque and get a $10 OBD2 Bluetooth, easy peasy and you can check all important generic sensor readings for free. 5-10 min will tell you more than you could ever know
 
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