Oil cover spark plug threads

Joined
Jun 10, 2002
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3,735
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Chattanooga, TN
I changed the plugs recently on my 2012 Lincoln Hybrid, 87,000 miles. Two of the 4 plugs had oil on the threads, one of them just loaded with oil on the threads. The electrode was fine, iridium and platinum tips seemed fine, just oil coating and yellow on part of insulator. So, after a couple of hundred miles I pulled the new plug on the cylinder that was really coated, the new one has a slight coating of oil as well.

So, this engine has never used oil, in fact some fuel dilution as the dipstick will actually rise over the course of a OCI. Now it could be fuel on the threads but feels like oil. No indications prior to plug swap, no misfires, or anything to indicate an issue.

Do I just let it go on a 9 year old car, or assume I have to pull the valve cover and see if a valve or plug seal is bad, or bad ring. To have a tech look at it, well, probably $200-$800 depending.

What would you do? I am assuming that being a hybrid; that the constant starting and stopping of the engine during city driving is not an issue with hybrids?
 
Joined
Mar 20, 2008
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12,489
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You probably need a valve cover gasket and spark plug tube seals. The job is easy since it's a 4-cylinder. If you can change the spark plugs, you can replace the valve cover gasket and tube seals :)

Mahle and Fel-Pro are good. Their valve cover gaskets include the tube seals.

Don't let it go because the oil will ruin the new plugs quickly, depending on how bad it's leaking. It's only $30 and 15 minutes.
 
Last edited:

Spector

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Joined
Jun 10, 2002
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15 min, you must be thinking of a 1960s engine. Multiple hoses etc covering valve cover, fuel rails etc. I will get it checked out.
 
Joined
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Messages
12,489
Location
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15 min, you must be thinking of a 1960s engine. Multiple hoses etc covering valve cover, fuel rails etc. I will get it checked out.

The only Ford I replaced the valve cover gaskets on was a 2002 Focus with the Zetec. The job was very easy. All I had to remove were the spark plug wires. Since yours is COP, it's even easier.

I tried to look up pictures of your 2.5L hybrid engine, but all of them have the engine cover on! I couldn't find a pic of the 2.5 hybrid with the plastic cover off! Does they hybrid have anything on top of the valve cover that the non-hybrid doesn't? :unsure:

Just be glad you don't have the V6 :D
 
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