Super Chevy
Click here to find out more!

Sparkplug covered in oil in only one cylinder

Super Chevy
Item Posts    Sort Order

Sparkplug covered in oil in only one cylinder

mgrosevear2 mgrosevear2
I love my Chevy Chevette! | Posts: 1 | Joined: 02/13
Posted: 02/18/13
08:22 PM

I have a 1965 C-10 with a 350 in it from an early 70s el camino.  I am getting alot of oil on only one of my spark plugs and it is causing that cylinder to constantly misfire after driving a couple hours.  I have cleaned and replaced the spark plugs and its the same problem after only a couple days of driving.  I know its not the valve covers because I dont see excessive oil dripping down the side of the block.  Any ideas on where to start troubleshooting? all help is appreciated. Thank you.  

68scott385 68scott385
I have an SS396 tatoo | Posts: 325 | Joined: 07/09
Posted: 02/19/13
06:51 AM

Is the oil on the inside of the cylinder? Piston ring(s) lost tension, oil blowby causing oil fouling of the plug. Intake gasket leaking from the bottom, sucking oil mist out of the valley into the intake runner.

Is the oil on the outside of the cylinder? Breather in valve cover blowing oil out? Power steering pump or hose leaking? Front cover to oilpan seal leaking, blowing oil on spark plug?  
68scott385 68scott385 68scott385

Bobs427 Bobs427
I love my Chevy Chevette! | Posts: 2 | Joined: 02/13
Posted: 02/20/13
05:11 AM

Yeah do a dry compression test. Then do a wet compression test. Compare the both and if the dry is lower then the wet. Pull the head off that side. You either have broken or worn out piston rings. Time for a rebuild...

Bob Aka-pepsi1  

wally0143 wally0143
My first time was in a Chevy | Posts: 186 | Joined: 07/09
Posted: 03/13/13
03:58 PM

I would try replacing your PCV valve, especially if the plug in question is close to it. You could have a bad valve seal on that cylinder, but valve seals usually wear out uniformly.  
Nobody knows everything but everybody knows something