I noticed today that the area around a single plug was dripping oil so I pulled the and was greeted by this mess




So where should I start? I have a head gasket kit and new plugs on hand so turn around time shouldn't be long. Take the valve cover off? Would this explain why I had an upstream o2 sensor die?

 

Yeah, the odds-on bet is a blown head gasket. Of course, there are other ways to get oil there.

If it is only oil on 1 spark plug then you can rule out the easy to fix "overfilled oil" option.

Valve seal failure, cracked head, and cracked block could also, in theory, sometimes cover a plug with oil.

Failed piston rings?


If the oil was only in the spark plug well until you pulled the plug out, then the valve cover gasket is probably leaking. That's easy/quick/cheap to fix. Try tightening the bolts in case they are loose (do not over-tighten) after you replace the valve cover gasket.



If the oil is on the spark plug tip (inside the engine), the piston rings are probably worn IF the DISCO is emitting blue-gray smoke from the exhaust pipe.

 

Those Bosch 2X are CRAP.... LR's DO NOT like any Bosch plug with a flush mounted center electrode. Hopefully your replacements aren't Bosch. Looks to me like a leaky valve cover gasket as the plug looks fine.

If it was something internal on that cylinder the spark plug would look much much much worse.

 

Previous owner. I have NGKs going in.

Should the leaky gasket be visually obvious? Just trying to gauge how far down I need to tear into this motor

Hard to tell if it was inside the engine or only on the plug. Tip wasnt covered in oil so maybe just the plug. Plug also didnt take much effort if any to remove. Almost felt loose. Have to check the others too and see how tight they are

 

Cool. You might be real lucky here.

Seems prudent to replace just that 1 plug while testing, plus replace the valve cover gasket on that side.

 

My first question would be...was the plug tight? If not, probably more fuel residue than actually oil. Fuel gets blown past the seating ring on the sparkplug and leaves a wet residue around plug.

Granted, since you have that plug out...pull the rest and do a compression test. Might as well know the condition of the cylinders, for sure.

​​​​​​​ Brian.

 

You may be right. I had someone else take a sniff and they it smells like gas. Make since because it was the most loose plug on that bank. I'll put new once in and just watch it.

 

Lots of reasons for spark plugs oiling. The plug may have failed, plug lead failed, coil pack failed, piston oil control ring failed, blown HG, IMHO start with the easy issues first and then if no success dig deeper. IMO always use genuine NGK spark plugs, they rarely fail, as there are many fakes around (I sound like Trump). Good luck.

 

X1 ......... a comp test tells everything about the state of the pistons and upper engine.