oil on spark plug threads


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By oldcarmark - 16 Years Ago
I am finding oil on the plug threads.The rocker gaskets are not leaking and the area around the spark plugs is dry.The plug area in the cylinder is not oily.I have cleaned all the thread area in the head but I am still finding oil on the threads when checked after a few miles of driving.Any ideas? 
By Nick Brann - 16 Years Ago
Hi Mark,  On my Y-block I also find oil on the threads when I pull a plug, but I put a couple of drops on each plug before installation.  Did you install these plugs, or was it someone previous to you?  I don't think it is something to be concerned about.  When I worked in the spark plug business, we were told that if you oil the threads before putting them in, you should reduce the installation torque by about 1/3.  So if you can get a torque wrench in there, use 10 ft. pounds instead of the normal 15 ft. pounds.  Good luck, Nick Brann - K.C., MO
By rgrove - 16 Years Ago
Mine wind up the same way, BUT I dont oil the threads prior to install; just a touch of anti-seize.
By MoonShadow - 16 Years Ago
Ditto! I always have oil on the plug base's when I pull them. Not sure where it comes from but no harm no foulWink Chuck in NH
By oldcarmark - 16 Years Ago
Thanks for your input everyone.I don't put anything on the threads prior to install.I cleaned them all off last week and cleaned the threads in the  head.Pulled them out again yesterday to check and their all oiled again.Doesnt seem to hurt anything just not surewhat was going on.
By oldcarmark - 16 Years Ago
Thats what I am wondering.There is no external source of oil especially since this is in all cylinders.The plugs themselves are NOT oil fouled.Thanks
By MikeLongIsland - 16 Years Ago
Thanks, was wondering that myself, but on the bright side, it makes them easier to remove.

Mike

By pegleg - 16 Years Ago
Most of the time I find this is caused by some oil weepage (slow leak) from the rocker cover gaskets. Look close.
By simplyconnected - 16 Years Ago
pegleg (6/20/2009)
Most of the time I find this is caused by some oil weepage (slow leak) from the rocker cover gaskets. Look close.

I agree.  But the seal at the plug shoulder holds back over 100 psi of compression and the threads are below that.  Piston rings hydroplane over smooth cylinder bores, causing oil to pass.  Since piston rings rotate, there comes a time when all those end gaps align (then they don't).  So, at what point did we pull the plug?  It could be long after the oil stopped.

How many miles are on your engine?  Seems to me this only happens on 'older' engines.