Oil in Cylinder #8 spark plug tube

[5.0Vonn]

Hey everyone, I'm new here and just looking for some information that I have not been able to find. I changed the spark plugs on my 2019 Mustang GT Performance pack 1. When I pulled Cylinder #8's plug it was covered in oil. There wasn't any oil on the actual electrode, just on the threads and sitting where the plug sits. From what I've read online it's most likely a spark plug tube seal. So I was thinking to just go ahead and replace the valve cover gaskets, and the Spark plug tube seals all around, and see if that resolves the problem. I can smell a faint oil burning oder now occasionally, but i'm guessing that's just the oil that fell into the cylinder from the plug change?? There's very small amounts of white smoke now upon start up but goes away when warm, again this didn't start until I changed the plugs. The plugs were cracked and chipped off as well. Does anyone have any other recommendations or thoughts? Thanks a lot!

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[Cobra Jet]

Hey everyone, I'm new here and just looking for some information that I have not been able to find. I changed the spark plugs on my 2019 Mustang GT Performance pack 1. When I pulled Cylinder #8's plug it was covered in oil. There wasn't any oil on the actual electrode, just on the threads and sitting where the plug sits. From what I've read online it's most likely a spark plug tube seal. So I was thinking to just go ahead and replace the valve cover gaskets, and the Spark plug tube seals all around, and see if that resolves the problem. I can smell a faint oil burning oder now occasionally, but i'm guessing that's just the oil that fell into the cylinder from the plug change?? There's very small amounts of white smoke now upon start up but goes away when warm, again this didn't start until I changed the plugs. The plugs were cracked and chipped off as well. Does anyone have any other recommendations or thoughts? Thanks a lot!

The plugs you pulled were chipped and cracked? Any images to post and what cylinders was the damage found?

 

[5.0Vonn]

The plugs you pulled were chipped and cracked? Any images to post and what cylinders was the damage found?

I’m attaching pictures of all of the plugs. The only cylinder that had oil in it was #8 and the plug with a little oil around the upper part of the plug is the one that came out of cyl #8.

 

[sms2022]

Unless this is normal for the coyotes, Looks like your engine got hot based on the burns on the porcelain

 

[Crew4991]

I’m attaching pictures of all of the plugs. The only cylinder that had oil in it was #8 and the plug with a little oil around the upper part of the plug is the one that came out of cyl #8.

Dinner is served.

 

[ORRadtech]

The way you described it I thought #8 was swimming in oil. The plugs you show didn't appear that bad. I'd be far more concerned about chipping and cracking. That will cause misfires.

 

[19gtaz]

Probably right about spark plug tube seals. How many miles?

 

[5.0Vonn]

Probably right about spark plug tube seals. How many miles?

It's got 67k miles on it.

 

[Coosawjack]

Oil won't cause a misfire unless it's on the electrodes in the cylinder since oil isn't a conductor of electricity.......I always had some oil in the tubes of my 04 Marauder and it never caused a problem in 257K miles!!

BTW.......those plugs look good for the mileage on 'em!!

 

[Garfy]

Unless this is normal for the coyotes, Looks like your engine got hot based on the burns on the porcelain

Actually, the brownish color at the bottom of the insulator where the plug shell is actually is quite common on many spark plugs on many vehicles. I was told by a spark plug manufacturer rep that it is caused actually by very slight seepage through the seal that's between the ceramic insulator and the metal plug shell. It's not a problem but when it fails badly, there is compression leakage and you could physically spin the insulator as it would be loose in the metal shell. It won't blow off but there would be sufficient pressure that if it was a regular spark plug wire (unlike the coil that is bolted in place) the wire would probably be blown out of the spark plug well. I've seen this brownish stain on lots of regular cars, not just high performance high compression cars.

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