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Oil Leaking into Spark Plug Cavity?


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I checked my plugs due to my 00'Forester (100k km's) hesitating. I found oil, fresh oil covering the boot that connects to the spark plugs tip. Not just on one of them, but all four!

 

I am not burning oil. Exhaust is very clean. I have always used synthetic oil. I replace the plugs today and went for a 30 min drive, 20 of which were spirited. It drives like new again.

 

I excluded the possibility of a cracked engine block since no burning of oil or coolant coming out exhaust.

 

One of the plugs had a dark sludge on it. This one seemed looser that the others as well. ALL tips were nice and brown which means no oil in combustion chamber.

 

Question: What is going on? Anyone else had this problem?

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Originally posted by daja

I checked my plugs due to my 00'Forester (100k km's) hesitating. I found oil, fresh oil covering the boot that connects to the spark plugs tip. Not just on one of them, but all four!

 

I am not burning oil. Exhaust is very clean. I have always used synthetic oil. I replace the plugs today and went for a 30 min drive, 20 of which were spirited. It drives like new again.

 

I excluded the possibility of a cracked engine block since no burning of oil or coolant coming out exhaust.

 

One of the plugs had a dark sludge on it. This one seemed looser that the others as well. ALL tips were nice and brown which means no oil in combustion chamber.

 

Question: What is going on? Anyone else had this problem?

 

Your spark plug tube gaskets are leaking. There are two "tunnels" in each valve cover through which the spark plugs are threaded into the heads. If you're gping to replace these, you might as well replace the valve cover gaskets as well.

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Originally posted by 99obw

AFAIK the '00 Forester has a SOHC Phase II engine, so it doesn't have spark plug holes, the spark plugs are on "top" of the heads like a SOHC 2.2. If I am right it means that your leak is coming from the valve cover gasket.

 

Nope. There are "tunnels" through the valve cover on the EJ253's. Check out http://www.cobbtuning.com/images/sohc-engine03.jpg

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