Spark plugs flashing blue at night

[joshwilson3]

On my 89, a while back I had put in some AC Delco spark plugs. Then noticed the nuts were rusted out a month later. So, I then put in NGK V-Power 5155.

I had recently popped the hood at night with the engine running. And noticed blue flashes coming from both sides of the engine at the spark plugs. From staring at the blue flickering lights, then shinning my flashlight is how I was able to tell where they were coming from. I know at least 4-5 were doing it. But there are lots of things in the way, so it is hard to see all of them. My guess is all of them were doing it.

It looks like it is coming from where the porcelain meets the metal nut on the spark plug. I'm not sure if it is coming out from where they meet, just coming off the end of the nut, or maybe shinning through the porcelain.

But it does look like to me the blue flickering on/off blue lights goes all the way around the spark plug. Its kinda hard to see, but I could see a ring of light which tells me it went all the way around the spark plug.

Is this normal, bad spark plugs, or maybe the spark plugs are fine and it is something else?

 

[boomdriver]

its what you will tell the insurance adjuster when he ask "do you have any idea of how the fire started"?

 

[joshwilson3]

its what you will tell the insurance adjuster when he ask "do you have any idea of how the fire started"?

Yeah, but what's the problem. Bad spark plugs or the spark plugs are good and it is something else?

I just installed these plugs at the end of last year. They probably only have 500 or so miles on them.

I had also thought maybe anti-seize causing a bad ground through the threads or something?

 

[C5sarge]

No that's not normal. Don't your plug wire boots cover the whole plug end? Are the plugs loose? You should not see the plugs sparking.

 

[TedC]

Can you confirm if the spark that you see is really external, and not internal? Also, are you running the stock ignition system? They say not to use anti-seize on the newer coated plugs, but I did on my AC Delco Rapidfires. I actually changed the stock plug to the rapidfires for the same reason you did (surface rust). Take a screwdriver or pointed probe and attach it via wire to ground. As you bring the tip near the plugs you can better determine if this is external or not. I think you are seeing internal spark.

 

[LLC5]

On my 89, a while back I had put in some AC Delco spark plugs. Then noticed the nuts were rusted out a month later. So, I then put in NGK V-Power 5155.

I had recently popped the hood at night with the engine running. And noticed blue flashes coming from both sides of the engine at the spark plugs. From staring at the blue flickering lights, then shinning my flashlight is how I was able to tell where they were coming from. I know at least 4-5 were doing it. But there are lots of things in the way, so it is hard to see all of them. My guess is all of them were doing it.

It looks like it is coming from where the porcelain meets the metal nut on the spark plug. I'm not sure if it is coming out from where they meet, just coming off the end of the nut, or maybe shinning through the porcelain.

But it does look like to me the blue flickering on/off blue lights goes all the way around the spark plug. Its kinda hard to see, but I could see a ring of light which tells me it went all the way around the spark plug.

Is this normal, bad spark plugs, or maybe the spark plugs are fine and it is something else?

How does the vehicle run? OEM plug wires or aftermarket? It sounds like your spark plug boots may not be seated properly on to the spark plug, they need to "click" when pushed on to the spark plug.

 

[catbert]

How does the vehicle run? OEM plug wires or aftermarket? It sounds like your spark plug boots may not be seated properly on to the spark plug, they need to "click" when pushed on to the spark plug.

Yep. Blue sparks are my way of figuring out if I need new wiring.:eyerole...or the need to re-seat them at the plugs.

 

[joshwilson3]

No that's not normal. Don't your plug wire boots cover the whole plug end? Are the plugs loose? You should not see the plugs sparking.

Well someone told me its normal. They said it is called electroluminescence. And that spark plugs that exhibit that will flash a light when fired. I think I'll give NGK a call.

 

[joshwilson3]

No that's not normal. Don't your plug wire boots cover the whole plug end? Are the plugs loose? You should not see the plugs sparking.

Yes, the plugs cover the end of the spark plug. I would actually call it blue flashing lights instead of sparking. Where I'm seeing the blue flashing lights is at the nut of the spark plug, which is a good inch away from the plug wires.

The plugs should be torqued to spec as I torqued them myself.

 

[joshwilson3]

Can you confirm if the spark that you see is really external, and not internal? Also, are you running the stock ignition system? They say not to use anti-seize on the newer coated plugs, but I did on my AC Delco Rapidfires. I actually changed the stock plug to the rapidfires for the same reason you did (surface rust). Take a screwdriver or pointed probe and attach it via wire to ground. As you bring the tip near the plugs you can better determine if this is external or not. I think you are seeing internal spark.

I'm not sure if it is external or internal. But I guess one night I could get a long screwdriver, and some alligator clips/wire and connect it to the block. Then touch the spark plug with the screwdriver and see what happens.

 

[joshwilson3]

How does the vehicle run? OEM plug wires or aftermarket? It sounds like your spark plug boots may not be seated properly on to the spark plug, they need to "click" when pushed on to the spark plug.

It seems to run fine. Though I think it runs a little rich as the OEM plugs the PO gave me were carbon fouled. And the plugs I pulled that he had put in were carbon fouled. But I figured that might have to be because he had a miss problem from a bad FPR and also put in 24# injectors.

The plug wires are clicked into place. I don't see any blue flashing lights at the spark plug wire boot. They are only at the metal nut part of the spark plug which is a inch or so away from the plug boot.

I would be thinking the plug wires if the flashing lights was at the boot instead of an inch away. And it actually looks like the lights flash like they are coming from the direction of the engine.

 

[joshwilson3]

Yep. Blue sparks are my way of figuring out if I need new wiring.:eyerole...or the need to re-seat them at the plugs.

The plug wires are clicked into place. I don't think it is the plug wires as I see no flashing lights at the plug wires or boots at all. I only see flashing lights at the base of the metal nut on the spark plug. Which is an inch or so away from the spark plug boot.

 

[Mike McKown]

Put your rusty nuts back in the engine and see what happens. Or send them to me. I'll take all the rusty nut spark plugs you have if that's all that's wrong with them.

 

[joshwilson3]

Put your rusty nuts back in the engine and see what happens. Or send them to me. I'll take all the rusty nut spark plugs you have if that's all that's wrong with them.

Can't, I returned the spark plugs as a product defect and got NGK. I called AC Delco and they said the plugs base shouldn't rust. So I returned them.

They must have cheapened out, as I've got the OEM spark plugs. And they look nickle plated like the NGK. Though, I have read you aren't supposed to put anti seize on nickle plated spark plugs, but I'd put it on anyways since I've got aluminum heads.

 

[joshwilson3]

I called NGK. It's normal. I'm gonna leave them alone. Haha. Though they said I could smear some die electric grease on the insulator if I wanted to get rid of it. They said there is a small air gap where the porcelain and base meet. Which is right where I'm seeing the blue flashing lights.

 

[c4c5specialist]

Its NOT NORMAL!

You put an ACDelco 41-808 platinum plug in your engine and you will NEVER see that.

Allthebest, c4c5

 

[joshwilson3]

Its NOT NORMAL!

You put an ACDelco 41-808 platinum plug in your engine and you will NEVER see that.

Allthebest, c4c5

Is NGK wrong then?

I called their tech line and their tech said what I was seeing was normal. At least with their plugs. I guess all plugs may not do it. The tech said they get calls like that all the time. And told me you see it at the air gap where the insulator meets the metal case where that nut is. That is exactly where I'm seeing it at. The tech called it a corona discharge.

 

[TedC]

If these are "working as designed" spark plugs, then I would go back to ACDelcos. I use dielectric grease to seal out moisture and prevent corrosion, not control spark distribution. This sure is interesting.

 

[gmjunkie]

The tech called it a corona discharge.

I bet it is,he drank 1 more Corona and said "P*ss on It"!!

 

[Hib Halverson]

A faint blue glow--as opposed to big blue sparks arching from the plug to the surrounding cylinder head material--around spark pugs is called corona discharge and is normal.

Also, the Junkster's comments about having one more Corona then piss on it, is unnecessary work. Corona is such lousy beer, you might as well just pour it on your spark plugs then go buy something good to drink.