Engine Oil in Spark Plug Socket Area/Well

Hello Everyone,

 

I am writing about by 2002 Subaru Legacy GT/Limited which has 165,000 miles on it. I am the original owner and have used Mobil 1 oil for the past 80,000 miles. It is a non-turbo and has a 5-seed transmission w/ original clutch.

 

This past weekend I was changing out the spark plugs and discovered engine oil had somehow leaked into the spark plug well/socket area. I found oil in each of the 4 spark plug socket/well areas and the front plugs seemed to have more oil in them than the rears. The worst socket/well had I would estimate to be about 1 ounce of oil in it while the others were just wet. The car is not burning oil. I change the oil/filter at 6,000 mile intervals and add 1 quart at about 3,000 miles. I don't consider this excessive. I drive the turnpike everyday at normal highway speeds.

 

When I removed the spark plugs they showed normal/even wear and no signs of an oil burn or leak. The spark plug threads were dry although the wire set boots can off real easy as you can imagine.

 

I was putting on a new wire set at the time although it would have been eash enough for me to clean off the old ones and reuse them.

 

I would appreciate any thoughts/comments/advice on the seriousness of this leak and any suggestions you may have on how to fix the leak. The car has no other oil leaks and has been the most reliable car I have ever had.

 

Thanks in advance for your advice.

g

Well, you claim your engine doesn't burn oil but if oil is clearly on your spark plugs, that would be hard to imagine. Oil getting into your combustion chambers can be caused by numerous components.

 

You could have worn valve guides and/or valve seals, your cylinder walls could be "worn" or piston rings aren't sealing properly anymore causing excessive blow-by, or you could have crankcase vent hoses and/or PCV clogged causing excessive crankcase vapors.

 

If your engine is running okay, I wouldn't really worry about it; although your engine does have high mileage so doing a simple compression test could tell you if your piston rings are sealing.

Leaking into the spark plug well area but the plugs themselves are clean? Maybe a leaking gasket? Any sign of oil migrating from the valve covers?

I'd guess the spark plug gaskets are in need of replacing. You'd also want to replace the valve cover gaskets and rubber grommets. It's a fairly simple DIY job. I usually do one side a day or weekend. Obviously you'd want to take care of your leaky side first.

 

subarupartsforyou.com sells them as a set for a cheaper price than buying them separately.

http://subarupartsforyou.com/cp_partdetail.php?partid=7877

I too just pulled a boot on one of my plugs and noticed a fair bit of good looking oil in the plug well. Haven't owned it for too long so I'm going to pull a plug and see what kind of condition it's in. Is the only source for a repair manual online from Subaru (that 72 hours thing)?

As an update to my first post, the car burns 1 quart of oil every 3K miles and has done so for the past 100K miles. I view this as a normal oil burn. The car has no other oil leaks and the motor is very clean for its high milage.

 

I suspect the oil is coming from the top and not from the spark plug opening itself. Other than the anti-seize I used to put the last set of plug, the old spark plug threads were clean.

 

Thanks for the comments.

g

^^^ The gaskets I am speaking of sit on top of the tubes, you cannot see them unless you pull the valve cover off. This is where your oil is seeping in from the top, then getting trapped down in the bottom of the tube.

 

I doubt you are losing a great amount of oil due to this, but it will ruin the plugs over time.

 

I've replaced these on many cars, mostly Neons...I have no idea why. I've never owned one, just knew a lot of people with that problem

ive had this prob on my civic but havent experience it on my BH9 yet, but on the civic it was just the spark plug tube seals, that is the only way oil could get in there unless every spark plug tube was split.. and i highly doubt that would happen.

I would have to suspect the only place for that oil to come from is the valve cover gasket leaking. With that many miles, I would have to believe you are due for a new set. Good luck.

Valve cover gaskets are leaking similar to this guys issue.

http://legacygt.com/forums/showthread.php?t=84830

 

We see this plenty of times.

I misread the OP, sorry.