Is spark plug regapping substitute for new spark plugs?

[NICAT]

Hi.
Is center electrode the only thing that wears out by the time ?
Even though copper spark plugs are inexpensive. Just want to know what usually makes spark plug "bad"
Regards.

 

[StevieC]

This is a good resource for everything Spark Plug, It talks about some of the issues with them as they age toward the bottom.

https://www.ngksparkplugs.ca/tech-info-spark-plugs.cfm

 

[zzyzzx]

Is spark plug regapping substitute for new spark plugs?

Often it is, yes. If they aren't too worn.

 

[Chris142]

I have seen guys file and regap old plugs instead of replacing them. Happens a lot at the shops that are ran from guys south of our border.

Must be how they do things down there

 

[Snagglefoot]

I'm going to offer another viewpoint. If you go through the effort to get the sparkplugs out, don't bother to re-gap them. Use new ones.

One step further: those copper plugs are old, old,school. Buy Iridiums and you'll get 100,000 miles out of them.

If you really enjoy pulling out the plugs, then disregard my comments and carry on.

 

[PandaBear]

No, but it may save you some money if you don't care for your labor cost.

Sharp edges of plug electrode helps reduce firing voltage, they wear out first. Regap a worn side electrode may also increase stress to it and increase its likelihood of breaking apart. Also the deposit and wear on the ceramic / insulation remains, and increase the likelihood of carbon trace.

If I absolutely have to, I'd not run it for the same amount of distance like my first 120k on iridium. I might run another 30k afterward after every regap. For Copper I'd probably run another 15k after each regap.

 

[vw7674]

Re-gap copper core plugs at tune up time. 4-8k (or new)
Toss platinum & iridium at tune up time. 60-90k.
That was the intention of the manufacturers. Or so I thought/read?

 

[RDY4WAR]

I change my plugs and air filter every 30k miles. At just $3/ea for the plugs, that's cheap maintenance.

 

[Astro14]

When labor was cheap, and parts expensive, there were intervals to file (AKA dress, for a nice clean electrode in either case) points and plugs, then set the gap, timing and dwell.

That WAS a tune-up.

Now, parts are really cheap. They last far longer. Points don't even exist.

And labor is expensive.

So, we replace.

Dressing the electrode and setting the gap is a viable alternative to replacement, but only for conventional plugs (not exotic metal electrodes) and you must dress/file them correctly before setting the gap.

 

[y_p_w]

Depends on the type of plug. A dual platinum/iridium plug really only needs a clean set of tips where there's only a little bit of that iridium or platinum. As long as the rest of the electrode hasn't melted away, it's just a current carrier.

Now traditional plugs are another matter. They're great when they're new, but they eventually start fouling up. The spark is much better when they're new, with nice sharp edges that improve the ability to create a spark. These edges start wearing down and make it harder to create a spark. It's not really the gap that's the issue but the condition of the electrode. NGK has its V-Power plug where there's a notch in the center electrode. Denso has their U-Groove plug where they put a groove in their ground electrode. Either is supposed to increate the amount of edges and I believe also create a little bit of room for the spark.

It's also not quite correct to call them copper. Almost all newer spark plugs have a copper core to help with heat transfer. But the electrodes are typically made of nickel alloy to last in the heat generated. Then there might be platinum and/or iridium pucks/wires welded to the nickel alloy.

 

[y_p_w]

Originally Posted by RDY4WAR
I change my plugs and air filter every 30k miles. At just $3/ea for the plugs, that's cheap maintenance.

Depends on the vehicle. I think at this point most newer cars are spec'ed for expensive plugs meant to last 60-120k miles.

Platinum/irdium don't actually work better but they last longer. If you check NGK or Denso's application guide, they usually have a listing for a traditional plug even if the manufacturer specs an expensive OEM-style plug like an NGK Laser Platinum. Not sure if they say how often they need to be changed.

I kind of wonder what's the point for an I-4 where I can swap out the plugs in minutes. But for a V or boxer, it can be a huge pain to change out the plugs. I'm still kind of scared with my WRX.

 

[Snagglefoot]

Originally Posted by Chris142
I have seen guys file and regap old plugs instead of replacing them. Happens a lot at the shops that are ran from guys south of our border.

Must be how they do things down there


And why not. The mechanic can charge the customer for a new set of plugs for $18 for a V6 or he can earn an hour's wage to re-gap them. How much did he get paid per hour? The customer probably got a better deal with re-gapped plugs instead of new plugs. In fact he probably would have felt cheated if the shop put in new plugs!

 

[RDY4WAR]

Originally Posted by y_p_w
Originally Posted by RDY4WAR
I change my plugs and air filter every 30k miles. At just $3/ea for the plugs, that's cheap maintenance.

Depends on the vehicle. I think at this point most newer cars are spec'ed for expensive plugs meant to last 60-120k miles.

Platinum/irdium don't actually work better but they last longer. If you check NGK or Denso's application guide, they usually have a listing for a traditional plug even if the manufacturer specs an expensive OEM-style plug like an NGK Laser Platinum. Not sure if they say how often they need to be changed.

I kind of wonder what's the point for an I-4 where I can swap out the plugs in minutes. But for a V or boxer, it can be a huge pain to change out the plugs. I'm still kind of scared with my WRX.


I use cheap traditional plugs in everything and change them often. It's easy enough, even on the Camaro. Even with the longer lasting plugs, I'd find myself having to pull them to reset the gap at about 30k miles anyway so I just run the cheap stuff.

Our 632ci outlaw engine that turns 9,500 rpm with 15.5:1 compression uses cheap $2 NGK plugs. Never misses a lick.

 

[y_p_w]

Originally Posted by RDY4WAR
Originally Posted by y_p_w
Originally Posted by RDY4WAR
I change my plugs and air filter every 30k miles. At just $3/ea for the plugs, that's cheap maintenance.

Depends on the vehicle. I think at this point most newer cars are spec'ed for expensive plugs meant to last 60-120k miles.

Platinum/irdium don't actually work better but they last longer. If you check NGK or Denso's application guide, they usually have a listing for a traditional plug even if the manufacturer specs an expensive OEM-style plug like an NGK Laser Platinum. Not sure if they say how often they need to be changed.

I kind of wonder what's the point for an I-4 where I can swap out the plugs in minutes. But for a V or boxer, it can be a huge pain to change out the plugs. I'm still kind of scared with my WRX.


I use cheap traditional plugs in everything and change them often. It's easy enough, even on the Camaro. Even with the longer lasting plugs, I'd find myself having to pull them to reset the gap at about 30k miles anyway so I just run the cheap stuff.

Our 632ci outlaw engine that turns 9,500 rpm with 15.5:1 compression uses cheap $2 NGK plugs. Never misses a lick.

Depends on who is doing it. Most people don't do it themselves, and the labor can get really pricey. I wasn't confident enough to change the plugs on my WRX and was charged 2.5 hours at $100/hr. The plugs cost $60 at inflated prices.

Now I'm confident enough to swap the plugs on my wife's Civic. Even then - someone who doesn't feel confident doing it will probably pay more for the labor than the cost of OE-style platinum plugs. That may very well be a good application for cheap Denso plugs swapped every 15K miles.

 

[demarpaint]

Originally Posted by Snagglefoot
I'm going to offer another viewpoint. If you go through the effort to get the sparkplugs out, don't bother to re-gap them. Use new ones.

One step further: those copper plugs are old, old,school. Buy Iridiums and you'll get 100,000 miles out of them.

If you really enjoy pulling out the plugs, then disregard my comments and carry on.

That's my opinion as well regarding a car. OPE I might clean up the plug, gap it, and use it again, if I think it is in good enough shape.

 

[Kawiguy454]

Its not rocket science, its two pieces of metal a specific proximity to each other the wear they have is measured in thousandths. I used to sandblast them when i was a kid and there was even a small pouch looking thing specifically for blasting plugs. The foldout feeler gauges also had a fine file in them. If you don't mind spending the $$ then get iridium's and forget about it.

 

[Kestas]

Back in the days of leaded gas and 12K replacement intervals, I would clean the plugs by sandblasting them. I could get 60K from a set of plugs before the center electrode was too far eroded.

I believe the issue is deposits on the ceramic. I imagine with time they can become conductive from carbon deposits and cause misfiring.

 

[eljefino]

If I were to pull mine I might wear out the coating on the threads that works as anti-sieze if I reinstalled them.

I've done it, and I'll do it again, but it's something to consider.

Running copper Autolite 3924s in my Prius... they were $1.10 each and not much work to get out. Doesn't run any differently than with Denso Iridiums.

 

[pitzel]

In some cases, the answer is "no". The gap can be re-adjusted into spec, but the creation of a spark, particularly under conditions of high dielectric strength of air (ie: very cold dry air) is dependant on dielectric breakdown of air when exposed to an electric field gradient. It is well known that sharp edges create a higher electric field gradient than dull surfaces. So the natural dulling of the electrode of a spark plug during its operation decreases its performance particularly in the cold start scenario. Which, for a worn plug, even when the gap is re-adjusted, can actually mean the difference between starting at temperatures of -30, and not.

I've personally seen this in action in Canada.

 

[PandaBear]

Originally Posted by Kestas
Back in the days of leaded gas and 12K replacement intervals, I would clean the plugs by sandblasting them. I could get 60K from a set of plugs before the center electrode was too far eroded.

I believe the issue is deposits on the ceramic. I imagine with time they can become conductive from carbon deposits and cause misfiring.


One spec Lexus show on IS250 on plug inspection (instead of replacement) that I have seen online is to measure the conductivity between the center and side electrode. People always say it is never going to be conductive but they have no idea how much carbon direct injection can generate, that will gradually pave a track between them. So the spec is 10 MOhm, which means any measurable resistance is bad. And they spec 60k for iridium with the 3 prong design, so that means it is the fouling rather than the metal wear that retires a plug.

Originally Posted by pitzel
In some cases, the answer is "no". The gap can be re-adjusted into spec, but the creation of a spark, particularly under conditions of high dielectric strength of air (ie: very cold dry air) is dependant on dielectric breakdown of air when exposed to an electric field gradient. It is well known that sharp edges create a higher electric field gradient than dull surfaces. So the natural dulling of the electrode of a spark plug during its operation decreases its performance particularly in the cold start scenario. Which, for a worn plug, even when the gap is re-adjusted, can actually mean the difference between starting at temperatures of -30, and not.

I've personally seen this in action in Canada.


This is one of the main reason why precious metal plug and fine wire plug are better. They stay "sharper" than steel "copper" plug even if they dull.