The Truth About Spark Plugs....

I know it's an older thread, but if anyone is wondering this is what the RFI at plugs sounds like. It may not be caused by the plugs, but newer quality plugs can suppress some of this noise.

https://youtu.be/rO0GZ-WXP-8

 

Fact is, electricity takes ALL paths. The current flow is inversely proportional to the resistance - George Simon Ohm.

Each path to ground will carry current in proportion to the resistance of that path. The total sum of the paths equals the total resistance of the circuit.

If you think electric potential will find only one path to ground, look at cloud to cloud lightning sometime.

 

I pulled this Autolite spark plug out of my wife's F150. I think the side electrode is still in the cylinder?
I think I"ll stay away from this brand just based on this personal experience.

 

In the Foul Year of Our Lord 2022 - we have the Irridium Spark Plugs.

Now on a standard engine - by this, I mean a modestly energetic spark of modest voltage and amperage and RPM - they typically get 100,000 - 120,000 Km between changes.

On very high energy spark generating systems, with high compression, high firing rates, very high voltage and amperage, people report them as lasting about as long as ordinary plugs.

It has everything to do with the central plug core being a tiny wire of an electrode and the erosion rate of this with high power levels.

But with a modest engine, instead of changing the plugs every 10,000 Km as per the manual, I figure that at $20 Au per plug, instead of about $8 Au per plug, well in lasting say 10 to 12 x as long, the cost per plug per change drops to ~$1.20 per plug, along with all the time and effort in making only ONE plug set change, instead of 10 or 12 plug set changes.

So the next plug change, will be with the Irridium plugs.

I guess there are many benefits to be had for the LONG lasting gear.

For instance you can now buy coolant that is good for 1,000,000 Km or 10 years (whatever) - this to me makes a LOT more sense than doing a change and a flush every 50,000 / 100,000 Km.

You can buy oil filters that are very good and are rated for 15,000 Km - instead of the usual 10,000 Km - and since all my driving is straight non stop long distance driving instead of short distance, stop start driving, with a decent oil I can push it it out to 12 - 14,000 between oil changes.

By adding a teflon based gear oil additive to the universal gear oil, I can extend the oil changes in the gear box and differential out to around the same distances.

 

Me thinks if the cylinder is not burning oil, as indicated by the plug colour, which indicates there is little to no bore damage, then all the bits have been spat out the exhaust port.

 

I'm wondering how that happened?

my first guess would be the plug was seated too deep? maybe it was the wrong plug?

i change plugs on cars at least twice a week, usually the plug have gone so long that one or two of them don't fire anymore, leading the customer to my driveway... I've never seen a plug in an automobile do what happened to yours (i see it in two strokes on occasion).

 

OK there can be a multitude of reasons.....

I'd say the welder / welding process, of bonding the side electrode onto the spark plug body was a one off dud or there was excessive wear and tear in that part of the production line, or some stage of the production that preceded it.

I have NEVER seen the entire side electrode, come off a plug - ever.

Without very close up images from the front and side and top, it looks like the fusion was incomplete and the electrode has separated from the plug body - there is no tearing, or residual electrode on the body or tearing within the side of the plug body - it's a fairly clean separation.

I mean you can try this at home - get a good OLD plug, and using vice grip locking pliers, or a vice, and grip the side electrode and then pull it off - the weld will look torn up - because it is.

This type of weld though, looks like a brazed / silver soldered or some high temperature alloy welding, rather than a fusion type of spot or resistance welding.


And with the side electrode coming loose inside the running engine, it looks like the electrode has hit and chipped the alumina surrounding the centre electrode - before they got spat out the exhaust - this is if they were.... Not confirmed by a bore inspection.... It's an assumption.

BUT this plug is the start of the damage, it's not a picture of the plug that was put in to replace it.... If the car runs just fine and the replacement plug is not oiled up... then the bore / piston / rings are fine... or the damage is negligable.... I mean why pull out and rebore an engine because one cylinder is using a teaspoon of motor oil every month or similar...

But if the cylinder is scratched up, the exhaust valve is not seating properly, the compression is down by 10 or 15%, it's blowing a fine amount of smoke, and that plug in the cylinder is oiling up...

"From little eggs do great monsters hatch".

 

Just wanted to add, about spark plugs, when we drag race, some manufactures make High Ignitability plugs, and what they do, is conduct spark quicker, to allow more complete burn, and quicker spark wall, which will allow a more complete burn, and increased gas milage, and easier starting. NGK has one I have used, and impressed with NGK 91657.

 

Mpg is most likely better because the air is denser and therefore has more oxygen.
Also water sprayed in the intake will also increase power.
Just reading through the thread so not sure if it's old or still going....

 

For the record in case it hasn't been mentioned a human hair is around .003" to .005" so its safe to say it will make no difference whatsoever.

 

Dielectric grease on plugs is the last thing you want. It prevents the flow of electricity. And never put anti seize as it changes the torque, it facilitates tightening so it can lead to over torquing.