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What goes wrong with Spark Plugs? #4655885
02/04/18 01:38 PM
02/04/18 01:38 PM
Joined: May 2016
Posts: 293
New England
NibbanaBanana Offline OP
NibbanaBanana  Offline OP
Joined: May 2016
Posts: 293
New England
I have changed many, many spark plugs in my life but don't ever recall having a bad spark plug. I changed the spark plugs on the wife's Kia yesterday. The old Champion copper plugs were essentially perfect. The gap had opened about .005 in 30K miles but if I had regapped them I don't see why they wouldn't have gone another 30K no problem.

Have I just been tossing perfectly fine spark plugs all these years? What goes wrong with these things? It would be interesting to see how many miles could be gotten out of a set of spark plugs. Remove, inspect, regap, reinstall.


1993 Ford E350 5.8L, 68K
2002 Ford E150 4.2L, 85K
2006 Chevy Aveo 1.6L 215K
2013 Kia Reo 1.4L, 101K
7500 OCI, M1 5-30 winter, M1 10-30 summer
Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4655888
02/04/18 01:44 PM
02/04/18 01:44 PM
Joined: Jan 2015
Posts: 374
Chicago Burbs
KzMitch Offline
KzMitch  Offline
Joined: Jan 2015
Posts: 374
Chicago Burbs
Rooting for the asteroid!

Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4655893
02/04/18 01:46 PM
02/04/18 01:46 PM
Joined: Oct 2014
Posts: 11,856
Idaho
CT8 Online content
CT8  Online Content
Joined: Oct 2014
Posts: 11,856
Idaho
They wear out or leak current or have defects from the factory and then some.


2015 Ford F150 2.7
2018 Ford F350 6.2
Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4655904
02/04/18 01:55 PM
02/04/18 01:55 PM
Joined: Mar 2004
Posts: 1,375
Flaherty, KY
92saturnsl2 Offline
92saturnsl2  Offline
Joined: Mar 2004
Posts: 1,375
Flaherty, KY
I see two "normal" failure modes:

1) the gap opens up too large, which requires too high ignition voltage to fire
2) wear on the electrodes (center or outside) creates a rounded surface, which with increasing gap, this can requirer very high voltage to fire that the ignition system can't handle

I've only observed two outright spark plug failures:

One was on a vehicle I owned (2001 Frontier supercharged), the ceramic insulator surrounding the center tip broke apart. The truck would have an intermittent misfire and when I pulled the plugs, that is what I found on one plug. I have no idea what happened to the ceramic, it probably got crushed by the pistons and spit out the exhaust. Changed plugs and engine worked fine with no more misfire.

The other was a good friend of mine that does absolutely zero maintenance to his vehicles other than random oil changes. He fixes things when they break, which hasn't been too terribly a bad approach for him, as his vehicles routinely go 200k+ miles. Sure increases your chance of a breakdown on the side of the road though. He brought his 2008 Jeep Commander (hemi with 16 plugs IIRC) to me w/ 100k miles on it, said the engine was misfiring. We pulled the plugs and the originals were copper plugs with a lifespan of typically 36k miles. The center electrode was basically non-existant-- it was sunken down so far into the ceramic insulator, you could hardly see it. You could see arc trace marks across the ceramic insulator where it had been firing. The side conductor looked like the tip of a nail-- it has worn mostly away.

Spark plugs will never be something that will give you horsepower-- but they can hobble an engine if you let them go WAY too long, or there's some mechanical failure with them like a broken insulator.



1985 F-250HD 7.5L 4x4 135k- Maxlife 15w-40 HDEO
04 Odyssey EX 182k PUP 0w-40
96 Maxima GLE 250k QS Defy 5w-30
07 Chrysler Pacifica Limited 129k PUP 5w-40
Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4655905
02/04/18 01:56 PM
02/04/18 01:56 PM
Joined: Jul 2005
Posts: 30,446
NY
demarpaint Offline
demarpaint  Offline
Joined: Jul 2005
Posts: 30,446
NY
Google "spark plug wear chart", you'll see a ton of pics of normal wear, and everything in between.


God Bless Our Troops

Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4655915
02/04/18 02:02 PM
02/04/18 02:02 PM
Joined: Nov 2008
Posts: 12,558
NH
supton Online content
supton  Online Content
Joined: Nov 2008
Posts: 12,558
NH
I have to wonder if they are using a plating of some sort. Which, once worn through, would rapidly wear away.

Not sure how many misfires it takes to damage a cat. For the time and effort it takes to inspect... you can just replace. I guess you could keep spark plugs on the shelf in case you find a bad one--but then you've spent the money, and then you've spent the time, so why not just stuff in new ones & motor on for another 100-120k? [Assuming that is the replacement interval.]


2011 Toyota Camry, base, 2.5L/6MT, 163k, hers
2010 Toyota Tundra DC, 4.6L/6AT, 144k, ours
1999 Toyota Camry LE, 2.2L/4AT, 190k, his
Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4655928
02/04/18 02:11 PM
02/04/18 02:11 PM
Joined: Nov 2006
Posts: 19,937
MA, Mittelfranken.de
Trav Offline
Trav  Offline
Joined: Nov 2006
Posts: 19,937
MA, Mittelfranken.de
Other than electrode erosion, mechanical damage and fouling the only plug I have had a hard internal fail on was a new AC Delco back in the mid 70's. Probably shorted to ground inside for some reason, it failed within a few miles, otherwise there was always an obvious reason for the failure.


ASE L1, Master. Deutsch Meisterbrief.
Re: What goes wrong with Spark Plugs? [Re: supton] #4655929
02/04/18 02:14 PM
02/04/18 02:14 PM
Joined: Apr 2012
Posts: 5,163
MA
Wolf359 Online content
Wolf359  Online Content
Joined: Apr 2012
Posts: 5,163
MA
Originally Posted By: supton
I have to wonder if they are using a plating of some sort. Which, once worn through, would rapidly wear away.

Not sure how many misfires it takes to damage a cat. For the time and effort it takes to inspect... you can just replace. I guess you could keep spark plugs on the shelf in case you find a bad one--but then you've spent the money, and then you've spent the time, so why not just stuff in new ones & motor on for another 100-120k? [Assuming that is the replacement interval.]


Yeah, there are certain things you can re-use, but we're not in Cuba, if you're going to take the spark plugs out, just put new ones in. I think one of the failures is that the ceramic insulator cracks and falls off bouncing around in your engine.

Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4655996
02/04/18 03:23 PM
02/04/18 03:23 PM
Joined: Aug 2004
Posts: 4,639
Katy, Republic of Texas
blupupher Offline
blupupher  Offline
Joined: Aug 2004
Posts: 4,639
Katy, Republic of Texas
The electrodes wear out:



150,000 miles on an '04 F150

And these are off my sisters '10 Santa Fe with 150,000 miles:



Still looked good, gap was alittle larger than stock, but was running rough and hard to start.

I pulled the plugs off my mom's Saturn Vue with 120,000 miles and they looked new, but replaced them anyway.

Platinum/iridium has greatly improved spark plugs, especially the double tipped and fine wire ones.


1994 Honda VT1100: Peak 15w-40/PSL/2500 mile OCI
2002 Ford F150: GTX HM 5w-20/EcoGard Syn/1yr OCI
2012 Scion xB: QSUD 0w-20/CQ Blue/5k OCI

Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4656000
02/04/18 03:29 PM
02/04/18 03:29 PM
Joined: Aug 2008
Posts: 3,169
USA
Reddy45 Online shocked
Reddy45  Online Shocked
Joined: Aug 2008
Posts: 3,169
USA
Blupupher are those the infamous F150 plugs that end up requiring helicoil work to remove?

Re: What goes wrong with Spark Plugs? [Re: Reddy45] #4656011
02/04/18 03:38 PM
02/04/18 03:38 PM
Joined: Aug 2004
Posts: 4,639
Katy, Republic of Texas
blupupher Offline
blupupher  Offline
Joined: Aug 2004
Posts: 4,639
Katy, Republic of Texas
Originally Posted By: Reddy45
Blupupher are those the infamous F150 plugs that end up requiring helicoil work to remove?

No, these were the ones from the 3v 5.4 that broke in half when removing (I luckily got all 8 out unbroken).
The 2v 5.4 is the one that would spit out plugs and require a repair.


1994 Honda VT1100: Peak 15w-40/PSL/2500 mile OCI
2002 Ford F150: GTX HM 5w-20/EcoGard Syn/1yr OCI
2012 Scion xB: QSUD 0w-20/CQ Blue/5k OCI

Re: What goes wrong with Spark Plugs? [Re: Wolf359] #4656090
02/04/18 04:55 PM
02/04/18 04:55 PM
Joined: May 2016
Posts: 293
New England
NibbanaBanana Offline OP
NibbanaBanana  Offline OP
Joined: May 2016
Posts: 293
New England
Originally Posted By: Wolf359
Originally Posted By: supton
I have to wonder if they are using a plating of some sort. Which, once worn through, would rapidly wear away.

Not sure how many misfires it takes to damage a cat. For the time and effort it takes to inspect... you can just replace. I guess you could keep spark plugs on the shelf in case you find a bad one--but then you've spent the money, and then you've spent the time, so why not just stuff in new ones & motor on for another 100-120k? [Assuming that is the replacement interval.]


Yeah, there are certain things you can re-use, but we're not in Cuba, if you're going to take the spark plugs out, just put new ones in. I think one of the failures is that the ceramic insulator cracks and falls off bouncing around in your engine.


I agree entirely. It's very cheap insurance if there's a reason.


1993 Ford E350 5.8L, 68K
2002 Ford E150 4.2L, 85K
2006 Chevy Aveo 1.6L 215K
2013 Kia Reo 1.4L, 101K
7500 OCI, M1 5-30 winter, M1 10-30 summer
Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4656180
02/04/18 06:57 PM
02/04/18 06:57 PM
Joined: Jan 2003
Posts: 3,203
Southeastern, PA
Rick in PA Offline
Rick in PA  Offline
Joined: Jan 2003
Posts: 3,203
Southeastern, PA
Off the top of my head, I can only recall a few spark plug failures:

My car had a slight stumble, so I changed the plugs. These were double platinums, same brand I had run before. I usually change them out at 50k miles (cheap insurance). At ~25k miles, two of the four plugs had worn the platinum electrode totally away. New plugs fixed the stumble. Probably a manufacturing defect, either poor weld of platinum to electrode or bad platinum alloy.

My wife's van was throwing a code for a misfire in cylinder one. I had a shop diagnose it, cracked spark plug insulator. Probably installation failure on my part. Number one cylinder was difficult to get to and I had recently changed the plugs.

Many years ago, my wife's car wouldn't start. I believe this was our first car with fuel injectors. My brother had a shop at the time and he fixed it. Fouled spark plugs due to fouled fuel injectors. He advised me to run a can of fuel injector cleaner through the car once a year. I've been doing that since and never encountered the problem again (today's fuels and injectors are probably improved, but it's cheap insurance).


A wise man told me:
"Heat is your friend." and "Any oil is better than no oil."
Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4656195
02/04/18 07:22 PM
02/04/18 07:22 PM
Joined: Mar 2016
Posts: 1,425
Western S.C. since 1996
CR94 Offline
CR94  Offline
Joined: Mar 2016
Posts: 1,425
Western S.C. since 1996
Originally Posted By: NibbanaBanana
... The old Champion copper plugs were essentially perfect. ... Have I just been tossing perfectly fine spark plugs all these years? What goes wrong with these things? It would be interesting to see how many miles could be gotten out of a set of spark plugs. Remove, inspect, regap, reinstall.
Using that strategy, I ran old Champion copper plugs well over 100K a couple of times in the Mazda below. It didn't run noticeably better when they were replaced. The NGKs that were the first two sets in that car likely could've done the same, but I replaced them prematurely, following Mazda's recommended interval of 30K.


2011 Toyota Prius now at 92K
1981 Mazda GLC (323) retired at 606K
1972 Subaru DL retired at 190K
1954 Chevrolet retired at 121K
Re: What goes wrong with Spark Plugs? [Re: NibbanaBanana] #4656198
02/04/18 07:24 PM
02/04/18 07:24 PM
Joined: Mar 2008
Posts: 6,837
USA
slacktide_bitog Offline
slacktide_bitog  Offline
Joined: Mar 2008
Posts: 6,837
USA
sometimes oil leaks from the valve cover gasket and/or spark plug tube seal, fouling the plugs in no time hide

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