Scorched spark plugs

[FrankM]

I replaced my spark plugs today, I understand how to read a plug, but I’m not sure why the insulators are scorched, is this normal? 61k on the odometer

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[Paul McWhiskey]

What are we looking at? A little bit on the car, please.

 

[FrankM]

2022 ecoboost premium with 61100 mi. I bought the car in January, it has been idling rough when hot.

 

[Pistol_91]

Are you talking about up top? That's probably from moisture. I assume this is your first plug change at 61k miles? I wouldn't worry about it.

 

[GregO]

Use NGK plugs
Dielectric grease the ceramic insulator area only, do not apply to the terminal end.

 

[sms2022]

Normal for a turbo car imo. Just did plugs on my brothers Cadillac 2.0T and they looked the same. New plugs had it running right again. Ditch the engine cover if you have one unless you just commute with the car.

 

[ice445]

Very normal imo. It's some kind of ionization reaction that occurs with the atmosphere over time and leaves that residue.

 

[Skye]

The condition is called "Corona Stain".

https://ngksparkplugs.com/en/resources/5-things-you-should-know-about-spark-plugs#:~:text=Corona stain is completely normal,seal inside the spark plug.&text=While most NGK spark plugs,off the fine-wire electrodes.

2. Corona stain

Corona stain is a light brown or tan discoloration on the outside of the ceramic insulator above the metal shell/hex. Corona stain is created by the high voltage traveling thru the plug that attracts the dirt or oil particles surrounding the exposed ceramic insulator between the wire/coil boot and spark plug metal shell. Corona stain is completely normal and should not be mistaken for exhaust gas blow-by or a broken seal inside the spark plug.

 

[Hoofer]

“do not apply to the terminal end.

Explanation for this statement?

I’d submit the video below as justification for the OP TO USE A DAB OF DIELECTRIC GREASE on the inside of the spark plug boot, on the plug end where it fits into the boot, and on the opposite end of the cop wire.

 

[ice445]

Explanation for this statement?

I’d submit the video below as justification for the OP TO USE A DAB OF DIELECTRIC GREASE on the inside of the spark plug boot, on the plug end where it fits into the boot, and on the opposite end of the cop wire.

I've always wiped some 3m silicone grease on the inside of the boot and it serves me well. You don't want to pack it solid with grease because it can introduce some resistance

 

[GregO]

Explanation for this statement?

https://mgchemicals.com/blog/dielectric-grease-on-spark-plugs/

 

[Hoofer]

https://mgchemicals.com/blog/dielectric-grease-on-spark-plugs/

LOL.

Besides successfully using dielectric grease on spark plugs and boots for over 30 years myself with zero issues, I just verified the use of dielectric grease on spark plug connections, not just boot ID, with a very seasoned and highly respected ASE Certified Professional I’ve known for years. He’s also the Service Manager at a successful Ford dealership.

 

[GregO]

LOL.

Besides successfully using dielectric grease on spark plugs and boots for over 30 years myself with zero issues, I just verified the use of dielectric grease on spark plug connections, not just boot ID, with a very seasoned and highly respected ASE Certified Professional I’ve known for years. He’s also the Service Manager at a successful Ford dealership.

So you’re stating that the yellow highlights below are incorrect ?

 

[sms2022]

original COPs on my 150,000 mile charger. Grab some di-electric grease and wipe some on the porcelain. Put the COP on. Move on. That is the process I have used on every car I’ve owned. If some gets on the electrode don’t sweat it.

 

[ice445]

LOL.

Besides successfully using dielectric grease on spark plugs and boots for over 30 years myself with zero issues, I just verified the use of dielectric grease on spark plug connections, not just boot ID, with a very seasoned and highly respected ASE Certified Professional I’ve known for years. He’s also the Service Manager at a successful Ford dealership.

Just because there's two schools of thought doesn't mean one is the correct one, lol. Dielectric grease applied in the manner you're saying won't really affect anything after the terminal makes contact and scrapes it off, but to me it's mostly pointless. Modern plug wires and cop setups have a pretty tight fit around the plug terminal and ceramic, so a light coat inside the boot is plenty to seal out air and moisture.

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