What You Need To Know About Spark Plugs

[@SouthMainAuto]

Hey Charles, Good vid for folks wondering a bit about their plugs. I guess I have 2 questions. First would be you showed the plug in the beginning that had fouling on the last 1/4" of threads or so and you mentioned that this threaded portion extended down in the combustion chamber? I have to admit, in my career as a mechanic I have removed hundreds of heads on many different makes and models but can't say I have ever seen the threads of a plug extend beyond the head exposing threads to the combustion chamber. I have only seen them come flush or slightly recessed... Is that a VW thing? Seems to me that would make it almost impossible to remove or very very hard to say the least. Similar to the problem the 3v Fords that you mentioned. IMO What I think you are seeming is perhaps were the combustion gas migrates up into the threads over time. Remember the threads have to contact the head fully because that is what carries away the heat from plug tip (making the heat range accurate). For my second question you mentioned that an extended gap will take more voltage from the coil to jump the gap. I have to admit I have done some pretty extensive testing using a capacitive pick up on a scope looking at secondary waveforms and changing the gap on a plug from .010" to .090" and I must say I have never seen a change (or very little) at all in coil output or burn time that is discernible at all. As a matter of fact the only time I have seen any sort of an anomaly from a spark plug gap is when that gap "bridges" basically causing a direct short to ground, or a severe open in a secondary circuit causing an unintended gap out side the combustion chamber but other than that can't say I have seen gap alone affect coil output on a modern day high output ignition. So I guess my question with all that being said is have you seen measurable voltage differences on coil outputs from a worn or over gapped plug? If so what were the actual differences and examples you saw? very curious about that :) --Eric O. ( sorry for the long question :/ )

[@michaelherbert8213]

Eric, stop farting around and get to work, lol. Goodmorning.

[@SouthMainAuto]

Michael Herbert Hey come on I need my YT fix too!

[@frugalprepper]

Hey Eric O. There has to be a correlation between voltage and how big of a gap the arc can jump. Think of arc welding and think about things like high voltage power lines. The higher the voltage the wider the wires have to be spaced. In a spark plug I think the distances are probably so small of a change that the change in voltage is tiny, so tiny you may not be able to accurately measure it with the equipment you are using. I also consider the ridges on the ceramic of the plug. Those ridges are there to increase surface area to help prevent arc from going down the insulator to the base, so the voltage must be able to jump a gap significantly longer than the distances between the electrodes. My guess is the difference, though minute, probably adds up over billions of cycles to quite a bit of extra wear and tear on the coils, and the quality of the spark would suffer. Again, all tiny differences but when you consider how many time a spark plug spark in 100,000 miles it becomes more significant.

[@AuMechanic]

First question: The plug threads are not protruding into or exposed to the combustion chamber. When the head gets hot the hot end of the threads get a bit bigger, that allows some carbon up the first few threads. Get a lot in there over age and it can feel like the plug was hanging out in the chamber and got carboned up but not so. Worth remembering that threads and in a head get smaller at the cold end and larger at the hot end when the head is hot Which is why you always chamfer the top of thread on an exhaust manifold face to stop the threads near the surface shrinking and shearing off the studs like a bolt cutter at the face leaving the remaining broken stud left in there loose enough sometimes to unscrew when it is cold. So where is a plug likely to seize and break off, top of the thread. For taper seat plug, they tighten up at the cold taper end when the engine is hot making them tighter at the taper when the engine is running, so don't take taper seat plugs out hot, flat washer seal plugs not sensitive to it. And if you fit taper seat plugs hot when they cool down they may be a bit looser than spec so replace them when cold or if you remove them hot let if cool down before fitting them.

[@AuMechanic]

Second question: There will only be a small discrepancy in spark voltage, spark time and pre spark voltage observed with a difference in spark plug gap, but that is academic as we are not merely looking for an absolute voltage value at any point or just a wide gap, we are looking for worn and thus defective spark plugs. What you need to be looking for is a scope pattern that displays a defective plug, it may have a narrow gap and be defective in other ways namely parasitic insulation leakage from contamination. And we know that such a plug will break down at idle causing an erratic idle misfire. You can simulate that by using a can of fuel injection pressure cleaner after fitting a new set of plugs and ruining the new plugs causing an erratic idle misfire, and observe the engine ran better before you used the cleaner. And you can see this in the scope like a defective plug not by absolute voltages but by lack of a stable spark voltage or time as it misfires and an ugly spark line too when it does fire. Keep in mind long life plugs are not a construct of much better plugs it is due to combustion chamber design and fuel and ignition control that allows the plug to last a lot longer before they are contaminated.. We had platinum and palladium plugs in the 1980;s too but you could not leave them in an engine for 60,000kms because they got contaminated. Precious metal helps reduce spark erosion to stop the gaps getting too wide but likely the plugs will be contaminated to the point they are failing at any stage (rough idle) before the gap gets so wide the owner notices it. Because the coil has plenty of reserve current wide gaps just mean more load on the rest of the ignition system that can cause breakdowns upstream of the plugs if left long enough. High energy ignition allowed car owners to burn their plug gaps to the stumps before the coil or module or leads or all 3 fried. Ive had cars come in to be serviced with plugs burnt to the nose cone, rough idle but no regular misfire at revs when warm, cooked every other part of the ignition system though. All scorched from having to generate enough current to leap the great gaps of the long worn out plugs. Leads and coil fried and tracking where the small air gaps in the insulation manufacture finally ionizes and creates a leak path that turns into a crusty crater. Put it on the scope and the voltages are a bit high but not liked you'd pick it that easily, but what you will see is an erratic pattern being erratic misfires not limited to one cylinder but may be worse on some than others. So you replace the plugs and then see how much it has cleaned up and if not then its a fuel related misfire or upstream ignition misfire and if the plugs were bad enough for long enough that is not unusual to see something else cooked. There is no point inspecting plugs because these days unlike old engines and leaded fuel engines more so you wont see the contamination of them. Which the EFI pressure cleaner will demonstrate, that you can cause a brand new set of plugs to start erratically misfiring at idle right after using the cleaner before you even get out on a test drive and you can pull the plugs out and look them up and down all you like but you wont spot the problem with them, the cleaner is now impregnated in to the nose cone insulators and the only place the new ruined plugs can go is in the bin.

[@lyndonbushnell8080]

A mechanic that actually knows his stuff & teaches it, good stuff mate.

[@HumbleMechanic]

Thank you

[@punjabes13]

@@HumbleMechanic POG

[@michaelgibbons829]

Torque? Tighten till it breaks then back it off a half a turn...

[@HumbleMechanic]

;)

[@michaelgibbons829]

Sorry, I couldn't resist. It was an old joke we passed around when I worked at my buddy's machine shop years ago...

[@HumbleMechanic]

+Michael Gibbons hahaha.

[@chaytonruijsenaars3971]

be sure to snap the stud off in the aluminum block at the proper torque, proceed to next step, snap off hardened steel broken bolt extractor in the hole half in the block and half in the broken stud, congradulations you now have a very hard piece of metal in the same spot your going to have a coolant leak when its back together, its better to just drill it all the way out and break a lag bolt off in the hole instead

[@LYx461]

That was mad !

[@eovdubsvw8743]

I have all three types of spark plug gapers. I own two air cooled bugs, a cabbie, and an 03 Jetta TDI, love your videos. The Jetta has been a pretty good car so far, over 150k. I replaced the timing belt with parts and tools from Blauparts.

[@AZREDFERN]

The fancy metal plugs like Platinum and Iridium also have a caveat 1. They're not really pure platinum or iridium. A singe plug would cost $100. They do however contain very trace amounts in the alloy used to help with the heat of forced induction and high compression. 2. They won't make your engine run better or add power. if anything they are POOR conductors and can create problems. 3. True rare metal plugs come with multiple leads. This give the spark more options to choose the least resistance (because they're poor conductors), and slightly lengthens plug life as leads wear away. They still only throw one spark. 4. It's best to stick with EXACTLY what your engine came with. The engineers that designed it are much smarter than you (usually). Plugs have plenty of other quirks such as internal resistance, surface resistance, resistance at operating temperature, resistive resistance, etc. When the manufacture factory tuned your engine's ECM and other variables, they did it with the factory model plugs installed. It is however a good idea to double check the assembly line's work. Plenty of cars roll off the line with random spark gaps, +/- 0.01 sometimes, slightly different resistance, etc. With anything electronic or mechanical, it's best to "marry" them. Have all the identical parts spec the same, and always use them together.

[@jimervin387]

I've never used a torque wrench on the plugs in my old 350 Chevy truck engine and don't believe I've ever seen any torque specs on them either. I've always tightened them the way I do my oil filter. That's finger tight plus about half a turn. I believe I learned that system on my Model A Ford.

[@frankdalla]

Torque spec for a 350 chevy = 25 ft lbs

[@dneitzke]

Excellent presentation,and professionally done, I'm a NGK freak as I found nothing last as long in my experiences over the past 20+ years, Your advice on Torquing spec's is so very important, most people just don't get that.

[@youcanthandlethetruth6454]

I have ngk iridium

[@vw4x4]

Do you use anti-seize compound on spark plug threads?

[@karljolley8346]

thanks for that education on spark plugs. question; is there an easy way to check if good/bad "transfer case motor or actuator" on a jeep renegade 2015? I have an intermittent "service 4wd system" dash light = on one day then gone. Inspected the connector plug, is clean and dry. I take the "intermittent" as a warning that something is not happy....

[@jeremymenchaca]

I torque my spark plugs using the German method. Gooden tight.

[@roobear5357]

Guten tag to you too!

[@SaracenArrow]

Your knowledge is amazing. I like how you put in what ifs and worst case scenarios. Great vid.

[@HumbleMechanic]

Thank you

[@onogrirwin]

Engineering explained brought me here, glad I found this channel!

[@kenbobca]

Thank you for this video. I've changed many spark plugs but it's always good to have a refresher video to keep doing it right. Oh, and I agree whole heartedly about using a torque wrench. It only takes one stripped out spark plug hole ($$$$) to make anyone a believer in torque wrenches.

[@pdiddyflyers4eva]

Hey Charles, was wondering if you could quickly/briefly describe the different appearances plugs can get under different engine conditions? For instance, what would a plug look like that was in an engine that was running lean versus one that's running rich? Thanks as always and great video!

[@Squatch69]

If it's running rich the plug will be black

[@danr5105]

I can remember when the Type IV engine started appearing in the VW Type II Bus. The type IV engine used the longer plug and it was not at all uncommon to find a spark plug for a Bug (shorter) in the Bus engine. It was also common to find a couple of plugs rolling around under the sheet metal on the Bus engine (magnetic spark plug socket made your life easier here). It used to be very common to have an "engine analyzer" in the shop that had an oscilloscope in it so you could look a secondary ignition wave forms, actually this was a very good diagnostic tool. Another good tool from "back in the day' was a simple two gas analyzer (HC and CO). These two gas analyzers really allowed you to put the finishing touches on your tune ups and aided in diagnosing a driveability concern. You had to remember to get you gas sample upstream from any device like a cat converter and remember to disable an air injection reaction pump as your gas readings will be distorted by these devices. I had a problem 1995 (I believe it was a 1995) 6 series V-12 BMW where these two tools would have been so very useful (car was an HC failure and we were no longer set up to work on this failure efficiently..

[@carlsocci379]

Love that reply, "took a shit". I gotta remember that. Thanks!

[@LastHumansGarage]

i like the technical deep dives. i rarely have time to watch any videos anymore, but i had to watch this one.

[@HumbleMechanic]

+LastHumansGarage I hear ya about that man!!

[@pdiddyflyers4eva]

+LastHumansGarage Looking forward to seeing that new shift knob and timing chain rattle fix!

[@treydaypnw]

+HumbleMechanic great vids man, hey I've switched to NGK Iridium in my 95 honda accord from the standard copper one that they say to use on the emissions sticker under the hood. Is it bad that I switched? will the car run different because I'm not using the exact plugs stated to use by the manufacturer?

[@fartman10284]

+fake priesthood apparently VWAG disagrees with you

[@ziggylothbrook8644]

I first saw you on Engineering Explained........you have a great channel and I watched like 20 of you videos....you know what you doing and biggest Shock......you care. well done

[@HumbleMechanic]

+Al Sipes thank you so much! I appreciate it. Love my dude Jason!

[@efrensaclolo7021]

How do you know when to change the splugs ?Can you mix Autolite and motor craft in a V8 engine?What is the best gap for a splug if you regap it?In a 4.6 L Ford truck.

[@BigRedtheGinger]

When talking about the coil on/near plug set ups, my 03 Galant has waste spark using both coil on and coil near. Cylinders 2 and 4 have coil on, Cyl 1and 3 are coil near.

[@Tomyp89]

Just installed some ngk's and they had no torqe spec, the picture on the box showed to finger/hand tight them and add 1/2 ~2/3 of a turn. I always add some anti-size on the threads. VAGs run in general on ngk's, bosch and beru plugs.

[@MuscleCarLover]

I use NGK and go by the hand tight + 1/2 turn rule with no issue

[@Sir_Scrumpalicious]

+Tomyp89 Torque specs are as per the vehicle and not as per the plug. According to NGK their plugs have a plating so using anti-seize is not recommended. The anti-seize compound acts as a lubricant which leads to over tightening since it will alter the torque values up to 20 percent.

[@Tomyp89]

+bjchase55 the torque in my case is for used/seated plugs. In order to seat the plug crush ring you should add a certain amount of angle(pressure), so i trust the plug manufacturer. The torque spec is in my application 20~29 Nm, and the 2/3 turn did felt like 29 Nm. Recommended or not, i did not have ane issues with it, threads look like new, no sease of plugs, and no loosening. About the 20% rise in torque, head bolts should not go in dry, so i will keep aplying anti seaze :)

[@christophermarshall5765]

Anti-size?? I think you mean anti-seize.

[@muddshshshark]

just tighten till the washer squashes.

[@michaelallen2501]

When I was attending automotive trade school (I'll leave the name out, since they were shut down by the government...) I distinctly remember my High Performance Powertrain instructor telling me a multi ground strap plug can block flame front propagation. He ran a $3-5 Champion plug in his 621 cubic inch HEMI race engine. And recommended OEM plugs for stock cars, and single ground platinums for mildly built engines. Taking consideration of heat range differences for compression ratio changes or boost/nitrous applications. We also went in depth about indexing spark plugs. Place the ground strap on the opposite side of the intake valve for naturally aspirated engines. And place the ground strap towards the intake valve on high boost applications, to prevent the boost from blowing the spark out like a candle. What're your thoughts Humble? I've always wondered why some German cars have multi ground plugs from the factory.

[@MuscleCarLover]

My dad once had a Champion plug fall apart in a bike engine he once had, completely killed it. Switched to NGK and never looked back

[@smoothcannibal5371]

always respect your car by using quality replacement parts. your engine costs thousands of dollars.

[@HumbleMechanic]

+Smooth Cannibal BINGO!

[@camperpro482]

Smooth Cannibal no shit shitlock

[@user-neo71665]

My engine cost me $800 plus some change. Bought, rebuilt, dynoed at 575 horses, and total cost.

[@DouEditz]

? wat engine

[@lazertag720]

Smooth Cannibal my friend sold his engine for car payment money, smart guy eh.

[@jerisern]

Where can I get a set of spark plug sockets with the little metal clips to hold the spark plug?

[@rogerfindley2720]

I don't even own a Volkswagen or Audi, but I still love all your videos! Thanks for posting them. I also love the collabs with Engineering Explained.

[@HumbleMechanic]

Thanks!!! I love me some EE too

[@littleaub3193]

The tork wrench is old needs, i took a lot of parts off my cars and never used one, you just know when to stop, if not your learn when you have to remove it, lol. but some that work on vehicles should use that tool and be safe and not sorry, lol, grate video, thats man.

[@aniruddhavispute]

Umm I was really looking forward to hear the differences between copper - platinum and iridium spark plugs. and also about single tip and double tip spark plugs

[@bengagnon2894]

Just use OEM style spark plugs. Don't bother using platinum or iridium if your car doesn't need it. It'll do nothing more at best. It might even get you lower gas mileage. It did on my older car. I sticked with copper because that's what the engine was designed to work with.

[@IIGrayfoxII]

iridium last 2-3x longer than copper so your better off just using one of those just for convenience

[@SI0AX]

I think iridium is better for modified cars making a bit more power as the plugs will have reduced life anyway. Modified cars also benefit from a shorter reach and closer gap. I've had a recommended plug change from as high as 30,000 (OEM is 60,000) to as low as 15,000 miles, but that is referenced to high boost turbocharged cars.

[@sofakingtouge2399]

SI0AX i use to think that as well. for modified cars go with copper or silver. silver works great but are expensive and have the shortest life. copper is a bit more affordable but again doesnt last as long. figure 20k on silver and 30k on copper. but they will conduct electricity the best. platinum and iridium are really more for everyday cars. they can last for years. they are however poor conductors of electricity. at 25psi and 6000rpm the last thing you want is a poor conductor.

[@dwc4343]

First off, spark plugs dont make any power. They just provide a space for a spark to jump. It does nothing else. It does need the proper heat range so it wont get fouled at idle. And performance cars use a wider gap to get more of the air fuel mixture between the gap to make it easier to fire off the mixture. Plus performance cars have higher powered ignition systems in order for it to jump a wider gap. The material the plug is made for make no difference in power or performance either. Just how much they cost. And duel, triple, etc. etc. ground plugs wont make any difference in power or performance either. Electricity folows the least path of resistance and it will only jump to one ground and it's done.

[@Title4914]

Hello, I know this is off topic but I started to keep a logbook for my car and I was wondering what do you think I should keep a log of? or what are the common things to keep a record of

[@jcadlols]

If your car has a single earth strap, pretty much any name brand, ie NGK, Bosch, Champion, Denso, etc plug with the correct temp, same reach, etc will usually be fine. Copper plugs don't usually perform any worse, they just need to be replaced more frequently. From what I've seen & how cheap copper plugs are, regardless of brand, you're likely better off running a good brand copper, than a dodgy brand platinum or iridium.

[@jcadlols]

Also, if your car is modified, there is a good chance you will need a cooler plug and possibly less gap, which you can't usually get with an OEM plug.

[@hanialsisi]

When i have to change the spark plug for a passat b6 2009 1.8TSi and after how many KM exactly you recommend????

[@anthonylipke7754]

Are the boots and connections on spark plug wires all pretty well interchangeable?

[@okaythen001]

awesome video, learned a lot. how do you make sure you don't cross thread when installing? go counterclock first to let it seat in ?

[@Adam-mm9re]

just start the thread by hand to prevent cross threading

[@redwingzfan5]

My dodge 4.7 had champion plugs when I bought it. I put ngk plugs in it and it had a whole new tone. Plugs do make a difference.

[@infringinator]

those chevy jerks shipped my truck with a stripped plug hole in the cylinder! Spark plug was halfway in for 140,000 miles, and unless I decide to fix it...the new one will be in there halfway in. And they just had to strip the one hardest to reach.

[@VIDSTORAGE]

100000 k plugs are amazing in my Nissan. Changed at 120000 k and was still running good.

[@Daddychill945]

I'm running a spark plug meant for a 30cc 4 stroke on my 66cc 2 stroke bycicle and it runs good but down the road will it break something

[@frankrock3965]

Good video. If the new spark plugs come in black like the one in the red box; how is one supposed to check whether there is carbon deposit on it overtime or there are unusual burn marks ?

[@Travis_Inlanzer]

I love the NGK iridium spark plugs for my Civic.

[@johnk9522]

Thanks again! Answered more questions than I was asking! I refer you to all my friends with a vw!! Great work always!

[@gristlevonraben]

do you think a colder plug is better with the methanol gas we use now that ignites faster because of the methanol?

[@SI0AX]

A slightly colder plug is only better if you're engine is producing a lot more heat such as when running a turbo charger near it's compressor efficiency limit. I assume, since you're running methanol, you have your engine tuned to run much harder to take advantage of the greater knock resistance.

[@SI0AX]

Gristle Von Raben Methanol actually makes the cylinder colder when it's burned. So you would have to advance the ignition timing. I think that's your problem, the fuel isn't being burned completely. Same happens when you put high octane fuel in a normal economy car with normal compression and no turbo. The fuel doesn't burn completely and gets wasted thus worse fuel economy and less power. Putting a colder plug would make things worse. You need to turn the ecu to advance the ignition timing and raise the air fuel ratio to generate more heat. That will improve the fuel economy and performance. Otherwise don't use methanol as an unmodified car isn't going to benefit from it. So in other words: methanol raises the octane rating of fuel.

[@ethan12313]

Gristle Von Raben Methanol? Probably ethanol if you are using pump gas. Methanol is typically used straight as race gas, or as spray mixed with water in the air intake to cool the air intake charge. Methanol is also expensive compared to ethanol.

[@osdoldsaltydog2120]

just did my 86 runner w/o a torque wrench. Worked perfectly

[@NoNonsenseKnowHow]

Very detailed video with lots of good info! I don't agree with the part about the thread discoloration through. Ive never seen threads protrude into a CC. Love the channel though! I just added you to the Featured section on my YT channel. Good stuff! Thanks!

[@glsdezign]

Very interesting explanation ... so I have a 1982 Fiat Ritmo (sold as the Fiat Strada from 79 to 82 in NA) what spark plugs should be used?

[@hookedoutfitters9513]

I am a mom and a grandmama that drives a vw passat - what kind of plugs would you reccommend me using. i have always used the dealership plugs because I think you get what you pay for - so do you think I should pay the higher price or what - thanks for the video I enjoyed it - I love my vw, it has 300,000 miles!!!

[@robiroca]

Hi, may I know what link you have to clean the spark plug terminal? because after I replaced my spark plugs the engine is now hard starting and I guess a dirt covered the terminal.

[@noowayynof2473]

I just noticed he has a Chris Fix sticker ayy lmaooo

[@HumbleMechanic]

Nice catch. ::)

[@germangutierrez7506]

Decided to learn mechanics, at least basic, then, maybe the more complicated things. I have to say this video was very informative and easy to understand.

[@HumbleMechanic]

Thank you.

[@V10PDTDI]

Hi Charles I remember working on a ABA engine of a 98 cabrio and the customer had replaced the plugs with Bosch platinum but with the big white electrode and the car was misfiring all of he rest of the system was ok I just replaced the new plugs with NGK or Bosch correct OEM number or plugs and the misfire went away could you elaborate more on the 2.0 L 8V on the mk6 Jetta engine that you mentioned in a older video that you notice that you have problem with the plugs failing early.

[@CaptainDerp]

I have a 2.2 ecotec engine in a 2004 cavalier. I'm not sure if the spark plugs have ever been replaced and it's at 90k miles. Assuming the rubber boots/wires attached to the ignition coil aren't torn, is it okay to skip replacing them? And should I apply grease to them when I reattach or isnit not necessary?

[@supercharged00gtp]

You mention 16 choices at the part's store and were given the recommendation of the person behind the counter. I'm sure you don't want to offend anyone but most people behind the counter at the part store have little if any training at all about vehicle, only how to run their computer system to look up parts. An interesting review albeit more time consuming would be show all 16 options available from the part store seeing the different brands and quality levels.Great into in the video though!

[@rjlopezmr.p2216]

Rich Beach I'm certified parts professional at a certain parts store and I'm sure there's at least one professional parts counter person at each and every parts store, so next time you come and visit one of the auto parts stores just ask either for an ASE certified parts professional or just a " plain " certified parts professional and I'm sure you'll get the help you need. I will have to agree though that, for the most part, all that a new hire is trained to do is to tell the customer what the computer says is right and not have the correct knowledge or skill to reassure the customer that is exactly what he or she needs to complete the task on hand. I too wish it were different however the automotive industry is always changing and the aftermarket is always playing catch-up that it is very difficult to educate all parts employees on the fly to keep up to date. the choice is personal to each and every employee whether to study and learn new automotive trends and tips or to just get by and do the bare minimum to keep a job. in one sentence " kids these days" rant over

[@martinschaffmeir7729]

Rj Lopez mr. P hey great comment. my son is an certified parts guy at my local advanced parts store and believe it or not he seams to know what he is talking about

[@roshanchitan1997]

hi, do you put some oil onto the sparkplug threads before installation?

[@trssho91]

No, just spark plug anti-seize. It's not going to interfere with conducting electricity, just be careful not to overdue it when applying. Some plugs have nickel plating and don't need anything.

[@plumkey197]

I've owned 2 engines with the coil-on-plug configuration-- a 4.6 L Ford V-8 (in a Marquis) and a 2008 Prius with the 1500 cc inline 4. On both of these motors, I found that taking a wet/dry vac and carefully cleaning the coils and surrounding area was essential. Even when the coils were removed, there was still a small amount of stray debris down at the bottom of the space around the plug itself in a couple of cylinders. I have a crevice attachment that fit perfectly to remove this trash so it didn't end up falling into the top cylinder area thru the plug hole. I've been working on my own cars now for over 35 years and have never used anti-seize on spark plugs because of the machined threads. Back in the day when points and condenser ignition systems were still common, The plugs never had a chance to seize because they were changed out much more frequently than today's car engines require. The only components I use anti-seize on are O2 and fuel/air mixture sensors, Honda crank pulley bolts, header bolts, and stock exhaust manifold bolts on the 454 Chevy because of their tendency to blow the gasket (usually on one side only, thank God) after driving through accumulated water.

[@tristancauser9423]

Thanks man! I live in vantuatu and we have such crap sparkplugs ... been waiting for over 2 years for some from Australia to come back into the agricultural store... I asked for portable sawmill sparkplugs,as long as they are the same size shape length with the tread being the same it will all be good right??

[@jenniferraymond8608]

Thank you - very informative, for me as a "virgin" to engine/motor stuff. Did not talk "down" to the viewer, was obviously, very informative. Also, not a "boring", slow-moving presentation.

[@dadkevin]

Iridium single ground spark plugs or 4 tails ground classic spark plugs for a 1.8t 20v golf 4? What do you think it's better?

[@jsmithkoko]

do you put grease around the threads when installing a new plug?

[@ramanpreciado2241]

Can you tell me about what would happen if you mix platinum and Cooper tip spark plugs If there all new?

[@HumbleMechanic]

+Raman Preciado 100% depends on the engine

[@justinzavala6497]

I learn lots thank you but question when u measure time for replacement

[@justinzavala6497]

How

[@420alt]

What about making sure the ground pron does not face the intake valve? I heard you may get some performance gains on this, however I have not tried it myself.

[@HumbleMechanic]

+420Alt while that’s true, you’re working in a high performance space there. Most people won’t have any need to index a plug

[@EternalyRandom]

NGK's are the best. I've used them for 20+ years, and never had an issue. They are more expensive, but well worth the money.

[@MuscleCarLover]

Still not very expensive

[@wartoc3708]

To seize or not to seize, that is the question. What is the recommended practice of using anti-seize on spark plugs threads? More over, when should/can you use anti-seize on threads (outside of the obvious wheel nuts)?

[@batoff01]

Thoughts on indexing them. I always told to when installing them.

[@HumbleMechanic]

+Dick Bateup for replacement as maintenance there is no real need. If you're building a performance car, then it may be worth it. I'll probably do some of that on the GTI before the head goes on

[@feplazas]

Charles, hi. Quick question... what's the gap for stock spark plugs on the Golf R/S3/Cupra 290? Thanks!!

[@russianrick8403]

I used the OEM Bosch dual fire platinum plugs in my 1999 B5 V6 for a long time and I would have infrequent issues with hesitation or misfires under load. At the advice of my grandfather, who had been a mechanic for quite a number of years, I switched to NGK single fire copper plugs and haven't had a problem since. This may or not be correct, but my grandfather was under the impression that multi-fire spark plugs were more prone to short out and give a bad spark.

[@scotty4885]

Charles-- good video. Question - what about reinstalling a plug that already has a crushed washer? Should you snug or torque?

[@HumbleMechanic]

I typically get them pretty close to initial torque. I usually put a torque wrench on those too. But not every time, especially when removing plugs for diagnosis

[@rickynaidoo2921]

What grease would you recommend to use for spark plugs?

[@lastempire7302]

You mentioned the factory one is pre-gapped. Do you mean if I am getting the after market spark plugs, I have to manually gap them to spec before putting them into the engine?

[@HumbleMechanic]

+Kevin Ping I would absolutely check it and see if it was correct or not. 1 minute of checking is well worth it.

[@lastempire7302]

+HumbleMechanic Thanks Charlie. What are the symptoms for bad spark plugs?

[@HumbleMechanic]

+Kevin Ping typical you'll get a misfire and flashing check engine light.

[@271production]

NGK plugs are where its at. Never ever had a problem with those

[@bengagnon2894]

It always depends on the car you're driving. I've had a terrible experience with NGK on my Volvo.

[@WhatTheHeckTV]

I have a 1984 honda big red 200es, and noticed some oil on the spark plug and around the plug area, and some smoke out the pipe, any help with this like is it rings or head gasket, I changed oil 2 weeks ago did some riding check the oil and oil is low thanks for any help

[@frogman6887]

I favor Polestar plugs. They come in a cardboard sleeve if I remember correctly but, I never trust the gap to be correct out of the box. And I've always adjusted them to gap spec from automotive manufacture.

[@daxfactor23]

about using a torque ratchet and extension. ive heard that you lose the effectiveness of the torque your trying to achieve. Is this correct or its a minimal difference?? ive done a spark plug change on a ford expedition where i would have to use two extensions and a wobble socket. Would the torque be the same?

[@HumbleMechanic]

+daxfactor23 i don't worry about it. It may be slightly off, but no more than a variance of a torque wrench.

[@daxfactor23]

thanks for the response. channel is awesome

[@idsoftware7]

What is the Gap tool with several gauges. (the one you prefer). ? Model please.

[@TheVersipelis]

Now that I know all about Spark ⚡️Plugs, I have some spark plug questions. 1. What’s the low down with buying plugs from country or manufacture of origin e.g. Motor Craft for a Ford, A/C Delco for a Chevy, NGK for Japanese, etc.? 2. Why would a Iridium Plug be preferable to a Copper Plug? Wouldn’t one conductor be the best?

[@olenaerhardt7725]

Can you put one different spark plug (different manufacture)? Or they all must be the same? Can you install 3 platinum and one iridium e. g.?

[@jasperdomacena6491]

I'm getting some hard cold start problems with my carbureted dirt bike and it has worse fuel economy than before.. should I replace the spark plug?

[@gurshannagra2431]

Hey Charles, I have a 2013 Passat tdi when you press the brake to start the car it's really jammed like when you press it after couple times when the cars off

[@HumbleMechanic]

+Gurshan Nagra there is a TSB or something about that. Let me look it up for you.

[@gurshannagra2431]

+HumbleMechanic did you find it ?

[@HumbleMechanic]

+Gurshan Nagra I was not able to find it. I will keep looking for ya.

[@nicselectronics81]

My Honda has a federal gap @ .044 and a California gap @ .052. wondering how it would run on California settings or if it'd be more efficient? 🤔

[@mameryjazz]

One of the best channels for mechanics and diyselfers. Thanks for being so detailed in your videos. I was wondering if you had a video on testing spark plugs and ignition coils resistance to find a new coil or plug that is defective. Your comment about the torque wrench just gave me an insight. Due to a cylinder #5 misfire on a Nissan Maxima 2005, I replaced all the spark plugs after ensuring that a compression was not the culprit. However, i did not replace the coils. Since this engine is not the easiest to replace spark plugs on and not wanting to remove the intake in case Coil #5 was the problem, I moved it to #6 position. Engine was smooth at first during the test drive but after about 60 miles of driving, misfire again. Very surprisingly, it was not a p0305 but a p0304 instead. Hum, now im wondering if I did not torque it too much or too less on Cyl#4. Cars problems can seem mystical sometimes. Since all the plugs installed are brand new oem, I want to check the coil #4 resistance for defect. If good then it is more likely a torque issue on plug installed in Cylinder #4. Any input Humble Mechanic?

[@friscostreetstories5403]

A very small piece of my center electrode had broken off , i noticed this when changing plugs. I unknowingly had driven many miles like this before I had a misfire and changed the plugs, and noticed the missing metal. In your opinion has that metal made its way past the valves and into the pan? I imaging im ok because Ive had no major issues. I hope to find the metal piece in the oil pan. So do you think Im ok at this point? Like I said I put many miles on the engine wirh the broken piece. Thanks. Mk4 R32

[@wyattoneable]

I appreciate the information Charles. Your video was well organized and easy to follow along.

[@MonsterNewfie]

Can you discuss the benefit of copper plugs over platinum? Copper plugs are recommended for my 5.7l Hemi and my 3.0l twin turbo N54 BMW engine.

[@douglascunningham1840]

On a 1.6L GDI engine. What causes a reddish spark from the spark plug coil engine wires, should wire tester get a blue spark.?

[@chriskeiley5343]

from my vast experience ( aftermarket and dealer) in the automotive field, cars are getting more and more picky. I would never install anything thing but factory plugs ( also available in most cases from the parts store) into any vehicle 2010 or newer.older vehicle are not as picky. I would recommend bosch or german plugs for a german vehicle, ngk or denso plugs for asian based vehicles, champions for dodges acdelco plugs for gm based vehicles and autolites tend to do well in fomoco vehicles.however this is only based on my knowledge. please do not use anti-seize as it tends to break down the electrical connection.... did the manufacturer? no for a good reason :)

[@Sovek86]

+chris keiley Even older actually if you have a GM vehicle especially the 3.8's as they had those funny waste spark ignition systems and it DID NOT like copper plugs.

[@guomondur9248]

What do you recommend the change interval for both plugs and coil pack ? I have ‘16 Q5 2.0 (31k miles)

[@craigt3689]

Hi re: the torque wrench you're emphasizing there, others have stated just enough tightness to you feel the crush on the gasket, or just a good tight turn with your ratchet.!? But not overdoing it.

[@NOBOX7]

humble mechanic , spark plug gap also effects timing , a short gap causes the spark to fire prematurely and a large gap cause a delay , so the perfect gap fires the spark plug at exactly the time the engineers designed the engine fire at . it will make engines hard to start as well

[@shengzzz7212]

When the gap spec asks for 0.039 - 0.043. How much should the gap be? Thanks

[@HumbleMechanic]

As long as it's in that range, you're good.

[@dwc4343]

Just put it in the middle.

[@Gears.and.Gadgets]

what do you think about "Iridium" spark plugs?

[@FrenchValleyAirport]

the best on the market

[@bengagnon2894]

Beware of the "shininess" of the iridium. It all depends on your engine. Do not put in iridium ones if you're not supposed to. I tried iridium spark plugs (7 $ each) and I tried copper spark plugs (1.50 $ each) on my 1992 Volvo 740 with the same gap. I ran better gas mileage on the coppers ones (which happened to be OEM) than on the iridium ones. On another note... 12 $ for a spark plug!? That's insane. And that pretty much sums up why I'll never buy a VW...

[@MrVestan]

12 USD for a spark plug in Sweden is considered cheap!

[@bengagnon2894]

A lot of spark plugs are 5 $ or less on RockAuto (for almost any model). Most are less than 8 $. I don't know about Sweden.

[@The_Referee]

Iridium are too advance for gasoline and cast aluminum alloy piston engine. our engine cannot gain the full benefit of the Iridium technology the high end platinum plug or OEM are good enough

[@slappyjoe6782]

I have subaru that was throwing some codes. So I took it to O'riellys to get the obd 2 to tell me the codes. Turns out it was high idle and cylinder 3 miss fire. Just recently changed spark plugs and wires, I thought I did something wrong. When I got home (20miles) I let me engine cool off for a bit. Than I started to take the wire off the plug and the boot started coming off and needles to say i took those wires back and upgraded the wires to something better. No longer have a check engine light and it sounds great.

[@racingwithbrad8260]

Charles, this has nothing to do with the prior topic of cars, however its not going to do any harm to my KTM Two-Stroke Dirtbike if I just continue using a spark-plug combination spanner and just threading in until i can't do anymore by hand. Then hold the combination-spanner about half way and just "snug it"? Obviously not to the right end and excessive force as that could strip the thread in the cylinder-head.

[@hellzaid]

Can u explain difference b/w iridium , platinum , and standard plug , is there any difference in power Thankx

[@HumbleMechanic]

+Muhammad Zaid I think that would be a great video. May take a bit, but I will add it to the list.

[@Bam221]

whats your guys thought about using never seize on the threads? I do it on all my spark plugs but wonder if its something you shouldnt do

[@HumbleMechanic]

+chris holmgren I never use it.

[@Bam221]

thank you for the reply. Been watching your video's for the past week and love them. I like the project car episode that i just watched, Good insight as i'm working on my project daily driver and getting no where fast.

[@HumbleMechanic]

+chris holmgren right on Chris. Thanks for that! Glad to have you as part of the community.

[@rasikh10]

What causes the yellowing on the ceramic part of the spark plug? Is that compression leak? Is the rest is coffee brown and clean but there is a dark yellow or orangish color on the ceramic park near the bottom side closer

[@labradormcgraw2409]

This guy really knows his stuff. Very informative video; great visuals. Thanks.

[@nialljamesbuckley]

wow - this video is utterly fantastic! thanks for taking the time to make and post this

[@braddowns17]

I always prefer OEM I don't like to use autolite plugs for a gm or Ac delco for a Ford and so on. with the old air cooled VW's I have seen champion plugs in them and every air cooled VW's engine I have rebuilt that had champion plugs had broken heads from the plugs. it pays to stick with the correct plugs on any vehicle.

[@toddmagee9168]

My mechanic buddy uses anti-seize on the threads and dielectric grease on the boot connection. Is there anything detrimental to this? Seems like the right thing to do.

[@gunchowder5065]

The anti seize could eventually cause the spark plug to come loose and need to be tightened again but that could take a longer time that the anti seize would last. Other than that, nothing's wrong with doing that

[@MrTheHillfolk]

Todd Magee Not a fan of anti seize at all, I've never had much luck with it doing what it says it's supposed to. It's just metal chips mixed with oil. Use plain wheel bearing grease, or even cv joint grease (i prefer that) it works fine. Even a dab of motor oil from the dipstick in a pinch helps em thread in nice without galling threads.

[@joevignolor4u949]

I always just spray some WD-40 on the threads to lubricate them and make the plug screw in easier. I've never had a problem doing it that way.

[@Travis_Inlanzer]

Just use very little anti-seize on the threads, it helps out a ton the next time you go to replaced the spark plugs.

[@crpth1]

Todd Magee - Keep that mechanic buddy. Not very common to see a professional doing all that. That's a good one. ;-)

[@trssho91]

Fun video. NGKs are crazy expensive, but my Nissans are only really happy on them. (NGK is original equipment for them as well)

[@HumbleMechanic]

+trssho91 Thanks!

[@trssho91]

+HumbleMechanic no sir, thank you for your excellent videos.

[@Airman..]

I am a mechanic myself and always recommend replacing these suckers at time of service intervals, i know that spark plug is only about a conductor a gap and an insulator nothing is wearing inside it except if there was a resistor but lets say there is no resistor and its due for replacement, is it possible to ultrasound cleaning it to remove tuff carbon deposits inside the electrode ? Hence deposits are the main reason for spark plug performance degradation!! I have access to a very power USC machine i should experiment this

[@harrykaplan2740]

I have a pit bike that needs a new spark plug but the one I just bought has the metal bit on top over the screw (opposite side to the spark) but the one that I needed to use doesn’t have that and it won’t fit. Is it possible to take it off for it?

[@ianirizarry30]

how about those plugs with a quad electrode? or the ones with just a ring for the electrode?

[@HumbleMechanic]

+Ian Irizarry my opinion is the car will almost always run better with the plugs the engine was designed for.

[@ianirizarry30]

HumbleMechanic thanks i was thinking of using Bosch platinum plus2 or the fusion ir plugs but if you think its best I'll stick with the oem premium ngk r plugs

[@Ratkill9000]

Have you seen much where people run the quad electrode Bosch spark plugs? I know the benefit probably isn't there outside of longer time between changes.