As a mechanic at a small engine shop I would say go ahead and change the plug. Start with the easiest option first. Obviously this solution (checking to see if the plug is good or bad) is good for people at home, however if you bring it into a shop you can't expect your mechanic to do this. We are working on flat rate and we aren't going to waste the time testing this. My biggest issue with this method is that it leaves lots of room for error and human mistake. But to each his own! Only my personal opinion and so long as your unit runs whatever method works for you is perfect! I enjoy the videos!
I agree. Cost wise, it makes sense to just replace it. My 4-wheeler suddenly won't start and I'm replacing gas, spark plug and filter just as a default (one at a time to determine where the fault lies). It's only a year old and has never been ridden hard so it can't be anything TOO bad (I hope!). But this video does help to explain just what a spark plug is and does and how you can identify issues. If your problem doesn't lie with the spark plug itself but in the wiring (or worse) at least this can help to narrow down any issues. Thanks for the video, mate!
@avery9997 We all know (sadly) that every mechanic (at his own garage) are heavy eater $$$ That's why THIS KIND OF TIME WAISTING is at the hand of every newby who try to repair is thing by himself. (At 18-30$ each plug uhm...) *Try to keep your "secret" of succes in your garage mister The Mechanic ; )
@@bacilluscereus1299 The R-type of spark plug is there for ONE thing.... to cut down the amount of current flow thru the plug which reduces the EMI that interferes with wireless devices. If the plug needs regapping, the gap has widened because of erosion (?)
Thanks for sharing your experience and knowledge Mr. Pender none of us were born with the answers and some just fake it to take our money. Your effort is a cut above.
I totally agree with you. In 40 years of owning power equipment I have only had to buy maybe 5 plugs. It’s just like the 3000 mile oil change, totally ridiculous nowadays.
You're right. I've been mowing lawns on and off for 40 years and have never changed a sparkplug on a mower, strimmer (US: weedwacker) or chainsaw. The mower/strimmer/chainsaws rust out or fall apart before the plug needs changing. Fuel filters on the other hand often need changing. Pull cords & recoil starters too. Carb/diaphragm occasionally. I have a multi-meter so I'll try this, my mower is not starting as well as it used to - although I expect it is a fuel related rather than electrical. Thanks Bruce ;)
You one of the lucky one, Last summer has replaced a coil of the Stihil Fs 90 , that only used less than twice Years ago, (because it too heavy, my sister put it away, get the electric. ) give it to me last year , installed a new coil & a new plug, start like a charm, last month it’s dead after 15 minutes run , installing a new plug ,it start up in first stroke. ? ? ? 😇😰
I was just cruising the CZcams for information on the air filter to my tiller. It's misfiring and I haven't had it running since last year. I'm no mechanic, I learn as I go. Too poor to afford to pay someone. I was wondering if my spark plug was bad and was going to replace it first. Thanks for this information. I just bought a multi-meter to work on my washer (got that running). I can use it to test the spark plug on the tiller now. Thanks for the information.
Thanks Bruce for that tip, been a mechanic for a long time and never heard of that.. ie: spark plug ohm test. Appreciate, I'm never too old to learn something.!!
Michael Noel As I mentioned below to remove any confusion. no--- I want to say thank you for replying to my video. I have more electrical experience in my life which I have brought into my mechanical knowledge.Bruce
You can only test a spark plug with the plug gap under max compression of the engine say 180lb/sq inch; The spark must overcome the densly compressed air !!
right!.... i'm with you now.... excellent, i couldn't figure out why when i put the spark plug to the engine block why i was getting a spark from the earth (the 'L' shape bend at the bottom of the plug) to the engine block, but no spark between the two contacts in the middle and why the engine wasn't firing up, starting, or running, so me plug must be knackered then because it's leaking if i think i'm right in saying after watching this then....
yeah changed the spark plug works perfectly fine now, engine starts first time, no problem at all, that's the first time i've ever known a spark plug to ever fail like that, very unusual.so cheers for that.👌👍
Your video identified my problem today. Electrode looked good and gap was ok but plug was leaking voltage to ground. I learned something new today. A big thanks to you.
Very good, thank you. On 2 cylinder engines, after plug cleaning, I swap them around to confirm that any problem is not plug related - might be plug wires, coil pack, or other issues. I note the "Side" with the issue...
Nice tutorial, I 100% agree with your rant on people replacing plugs for no reason. I find maybe 1 in a100 or less machines actually need a new plug, and that's with all the machinery I service. Most are just dirty or carbon fouled. A quick heat up of the electrode with a blow torch and they are like new. I made a video on just cleaning these things.
Yes that high resistance between the electrode and ground is like a short to 13000 volts. but not many plugs get to that point. most are just fouled with carbon on the outside
I do they same thing ,except I don't have a torch to clean my plugs. I wire brush them until they look new again. A lot of people don't even know how to repair a lawnmower
True. I run mowers weed wackers, dirt bikes, outboards, cars, 2 and 4 stroke bikes. In the past 20 years I've never had to change plugs. I give them a clean, gap them, test them and re-install. Good as new! Thanks heaps for the video.
I agree, I only replace plug if customer insists on or want top dollar for a unit for sale. Looks good with a fresh plug in if old one looks crusty. Thanks Bruce
You absolutely right. Just measure them again after cleaning. I think on one engine i dropped a piece of wire from the spark plug into the cylinder and wrecked the engine. Always a learning experience.
I 💯 percent agree with you. I thank you for your video. You taught me a simple way to check a plug. I usually let it run until the engine dies then replace it. Now I have a way to verify it’s bad. Thank you so much!!
New subscriber,good stuff.. 11 years on my toro 6.5 mower with the original spark plug and still starting and running strong.. Its all about maintenance and good gas habits.
You make a good point about the meter probes picking up resistance from your body. Keep fingers back on the insulated handles, let the spark plug sit on a non-metallic work bench, or a block of wood if it’s metal.
Yep, I have never changed a spark plug in any of my small equipment, chain saws, log splitter, roto tiller, lawnmower, etc. Clean, gap check, test and use. 👍
I have an old Snap on spark plug tester and cleaner. This is a big unit, probably well over a foot high and over a foot in length by another foot deep.To clean you use the silica/sand under air pressure. To test the plug you used just the clean air button to see the plug firing in the unit. It produced varying degrees of compression in the unit. That way you could actually blow out the fire in the plug if the plug was faulty. I used it many times over the years to detect a bad plug which btw wasn't that often. In those days of ignition points you could buy a single plug instead of a whole set..
Looked at a number of videos but it finally started to click here. Ariens Snowtek 20, comes with a LCT 136, worked last year but I needed the electric starter to start it. Would not start this year in prep for winter. It comes with and LCT recommends a Torch F6RTC, well I was getting about 4K electrode to ground but I found when I moved the electrode slightly I got zero ohms, at this point I carefully moved it to the snow blower and wallah Spark! I'm not sure how it is shorting but is is. 50 plus years and never saw a spark plug that would not work. What I saw here is that some do not work. It has to be pretty rare? This one is getting hung on the wall.
Yes the carbon inside the porcelain gap can conduct but if they are cleaned most of them can be revived as you say. I reuse plugs all the time and have only had a few that are duds.
Thanks for keeping it simple. I'm going to check my spark plugs as well. I even have a Fluke model 73 to check them with that I just bought. So far, it's a keeper!
Omg my father in law and I have been trying to fix my generator for three straight days. This video helped us fix it in the time it took to test the plug and drive to AutoZone. Thank you sir!
Bruce when testing the electrode with your ohm meter fine. But mate unless the electrode has a dead short to ground an ohm meter will not pick it up. Really to test between the electrode and ground you need an insulation resistance tester (megga ) which puts a high voltage between the electrode and ground and you will see if there is any breakdown in insulation. Which would not be possible with a continuity tester. The high voltage on the ignition system will find any weakness in the insulation between the electrode strode and ground. But still a good informative video .
Good vid. Most folks don`t have or don`t know how to use an ohm meter but, one doesn`t need a high dollar DVOM to check a plug. A cheaper analog, sweep type works fine. Least now, most can at least remove their plug from their "parts changing" list for a no start.
👍Totally agree. I find it funny when folks drop off their mower and the very 1st thing they say is they think the spark plug is bad😂😂😂 Most common issue around my neck of the woods is a dirty clogged carburetor. Thx for the video.
I am sorry .I am getting so any comments from you I don't have time to answer them all. i am doing 200 comments a day now as I have almost 40,000 subscribers. Plus editing and the work in the shop. Sorry buddy
@@BrucesShop - Hey man, no worries! I just figure if a good CZcamsr puts out good content then the subscribers should do our part by thumbs up & leaving a comment. I’ve heard it helps out a lot. (Algorithms and such) It’s always nice to hear from ya however it’s understood & no reply needed. We’re all here for ya in effort to grow your channel & show appreciation for the video help that you provide. Take er easy my Canadian friend 👍 (Ol KY 🇺🇸 boy here)
Hey, thanks for that tip, it never occurred to me to ohm out a spark plug! That's going to be pretty handy. And I agree with your rant! I think it's mostly people that don't understand trying to convince themselves they know about a subject. Mower doesn't start, must be the plug; TV doesn't work, must be the picture tube (Conventional TV obviously); vintage radio doesn't work, must have a bad tube; car won't start, check the oil. etc, etc, etc.
Now I completely agree with you on everything but depending on the aspiration of your vehicle (turbocharged or supercharged) will determine how much you should change your spark plugs. My mustang is turbocharged so i have to be spot on with my maintenance and repairs.
great information, i try to tell my customers when they bring me one for a tune up that i can throw the plug at it but its not always necessary and they usually opt to replace it anyway even if its good. i never thought to ohm these out, i always just wire the bail and pull the cord to check spark on the block with the plug pulled. this looks much easier, another great video. thanks for sharing
couldn't agree more, the spark plug that is on a new lawnmower will usually outlive the deck. the youtube ranters will say ... "they are only a buck"; problem is, they are waaaaaaay more than a buck and have been for years.
I just replaced the spark plugs on my Ford fusion hybrid after 182k miles! The electrode was worn to a small nub, but the car never showed signs they weren't working. Less vibration after replacing then though! Iridium tips on the new Bosch plugs.
You seem very very knowledgeable about the mechanics of the machines that comes in your shop as well as the electronics of the machines. Spark plugs , coils etc. I would love to see you do a video or videos if you would on say trouble shooting the electrical aspects of the machines. Example. How to check a coil, spark plugs, safety switches. E t c I would love to learn more about it from my favorite small engine mechanic here on you tube.
thank you sir for the video. helped a lot. believe I'm having issues with a spark plug currently on a small engine with only about 10 hours of use. however it's a crummy Chinese knock off spark plug and everything else I've looked into is checking out. good fuel, air cleaner. clean etc so slowly narrowing down the issue to hard to start motor. it's practically new so wiring and such all seems to be fine checking current on them as well. again thank you for the video.
Very good and thank you but on the "working" plug there is still no certainty with this test. The volt meter only has maybe nine volts across the leads while in normal working conditions the plug runs about 20,000 volts DC and at a way higher temperature. To really measure the internal insulation effectiveness to ground at that temperature would be the definite test. In any case the test shown here is to eliminate the most obvious bad plugs for sure. Thanks again.
BTH1 That is what I thought I heard this is KG5JWU. I learned what you are saying about 16 years ago when I was working on my old 74 Bug. Once I learned what you are talking about I stopped replacing plugs. I would check wires for oms = 1 per foot. I also made sure my gap ( points ) was good and timing was set ( gap plugs too). After I learned that I stopped spending money on ignition components over night. I went from spending a few hundred a year on parts to nothing. That bug cost me $500 a year including gas. Once I learned your secret. This gen will never understand.
Thank you, this was a huge help in troubleshooting. After testing my spark plug it showed it was bad, bought a new one and my lawn mower fired right up. Crazy, the original plug was less then a year old. I was hesitant to buy a new plug cause the original looked good.
Thanks for the simple explanation and demonstration! I will confess as one who is guilty of changing spark plugs to correct an ignition issue. I will use this test from now on, and look forward to more videos! Dan
I get what you mean. I just replaced the spark plugs in a car after the previous owner ran them for 200,000 miles, they worked but the electrodes were pretty much not there.
If it won't start it is usually the spark plug. The heating up and cooling down eventually cracks the ceramic dielectric. That said my 25 year old snow blower has the original spark plug. It is usually bad gas that causes problems in small engines, I put gas treatment in the gas I use for my small engines. My snow blower usually starts on the 2nd pull. I may have to replace it soon because the front end is breaking up.
Yes, that is a good way to tell if a spark plug is bad. One "BAD"test that many will do, is that they will remove plug from engine. Attach the high voltage lead to it, and then touch the base of the plug to the ground of the engine while pulling the starting cord and watch for spark at the gap. If they see a spark, they determine that the plug is good. But some times a bad plug will not produce spark when under engine compression!
I saw another video that suggested 5k is the normal impedance for a resistor plug. 20K seems quite high. I had a mower with a plug resistance of 18K, the mower wouldn't start. I replaced the plug, it started fine.
Maybe a confusion with your term leak through... I think what you're trying to say is that the carbon shorts the center electrode to be grounded portion of the plug. Other than that it was a good presentation because I already understood what you were trying to explain. The resistance varies on the condition of the plug or how carboned up it is...
P.S. On the other side. I bought a truck from my dad with 250K miles. I decided to check the plugs and when I got them out they had a gap the size of a match head and a half or more and the electrode was below the base of the threads, nearly flat on the ceramic and round. and the thing still ran fine. Ford 1994 F150 six. Red.
Yeah, and many people get charged for a “tune-up” on their small engines, consisting of a spark plug and air filter, blade sharpening....all they really needed was a blade sharpening and maybe CLEAN the plug, probably clean and replace the air filter if you’re in a dusty area. When I was growing up in Michigan, we had a nice lawn and didn’t get much dust stirred-up....air filter lasted a long time. Now, I get lots of dust, air filter gets dirty in a hurry.
If you're going to clean & re-use a spark plug you can get more life out of it if you not only clean it with a wire brush but file the contacts so they are both flat and aligned. I used to do this with a points file but any small metal not-too-rough file will do. Also re-gap the plug but only bend an electrode once or twice so that it doesn't break off in your engine.
It depends what yoyr fixing. For myself ill keep the plug till I have problems. However if im fixing or tuning something up for someone else I would replace it for preventative matanence.
I would recommend using a megger to measure the leakage across the ceramic on a spark plug as this is more effective for finding insulation breakdown as they use 500- 1000volts when testing. Also DO NOT USE A WIRE BRUSH TO CLEAN THE CERAMIC CORENOSE of a spark plug as this leaves a metal coating on the ceramic and will cause the EHT to track across it to ground then you have to buy a new one. You could try a sandblasting spark plug cleaner but you must make sure all sand traces are removed from inside the plug before 're using it. You do not want any sand to end up inside your engine.
Air filter, air filter, air filter, oil change every season, fuel filter every 4 seasons and then after 5 seasons check and clean the spark plug if your fuel consumption goes up because your voltage used on the lawn mower type system in general is so low that electrode wear is minimal. But your air filters and oil filters should be maintained every season as needed.
I have a quick and dirty test. If you hold the plug in you hand and jump backwards, it’s good! Verifying dielectric air breakdown exceeded 3,000,000 V/m. Meaning good spark, don’t need no fancy meter.
Mr. Bruce if interference is not an issue from the spark plugs in my riding mower, is there an advantage to use resistor plug? If I interfere with no one there is no use to resistor plugs is there? Thanks for this interesting video!!
Thanks for sharing your video on CZcams I never knew about using an ohms tester. People here my bitch about what you have said but as far as I'm concerned I have learned a lot and I sincerely thank you for it!. Believe it or not I think that doing this will definitely save me money in the long run because I have been spending far to much money on those damn spark plugs for sure!. However since watching your video I now know how to test them spark plugs and I sincerely appreciate your video and for sharing.
Joejava SIRS. YOU ARE ..ABSOLUTELY ...CORRECT...OHMS,RESISTANCE,VOLTAGES..ALL APPLY WHEN TROUBLE SHOOTING...ANY CIRCUIT..(automotive, lawnmowers,lighting circuits- these are ‘DC circuits’)...knowledge is amazing...makes repairs easier and satisfying thank you for sharing...KEEP-ON-WRENCHING..fellow UTUBERS
i used to replace them in all equipment i worked on but now if they work i just leave them alone if they work no point in replacing them unless there bad
If you don't have a omh meter and want to know if a plug is goo or bad, just take the plug out, leave the plug wire connected, sit the plug on the engine anywhere so that it is grounded, and then crank the mower a few spins. If you see the plug making a spark, then its good. If not, it could be a broken, or corroded plug wire. A test light will tell you, or just lay the end of the wire close to the engine and see if fire jumps to the motor, or lights the light.
I would caution one when checking a plug that way. Though one can check for spark that way, the cylinder can spray fuel out that hole and ignite and now one has a fire on their hands. I've seen it many times. So be careful.
Yes resting the sparkplug on the engine is hard to beat as as a simple "acid test": works/doesn't work. However, Bruce's technique should also detect marginal plugs that will work at least sometimes but just not as well or reliably as they should. I bought a sparkplug test light but I found it didn't work - at least not well - with the mower, I was disappointed. Probably intended more for cars & motorbikes. Just sitting the plug on the engine block worked better. (Thanks for the fire hazard warning George ;)).
I just did that and was getting spark. So i spent hours cleaning out the carb, adjusting, cleaning again, and adjusting again. It would start to fire up sometimes and then die. I tested the plug with a meter the way this guy was saying and according to the test it's a bad plug. Unfortunately the auto store here doesn't have the plug i need.
The real problem is that the companies that makes them do this deliberately so your spark plugs end up falling. It's all a Monopoly, I remember when I was a kid spark plugs back then worked great and work forever they don't make them like they used to they make them now to fail on you on purpose make them ground out and you loose Park faster and basically Bruce is telling us in the video is very true because this shit happens a lot and they just don't make them like they used to back in the day but for that reason they're doing that because they want you to buy more of them it's all in Monopoly like I said.
Yes, this is fine when in a pinch and it's your own equipment. Not the best practice for a customer, better to simply replace with a nice new properly gapped plug, even then you should still do the quick test even of the new plug for a customer. just my view. enjoy your videoes
Good informative video, however at 4-15 should you not be saying " adequate resistance to ground"? not " no resistance to ground"? Oops, just seen your correction, ie ,Conductivity. Thanks.
but there are expensive original spark plugs that has a little copper from inside should give reading between 2000 to 6000 ohm when we measure the tip and it's end without touchingthe ground electrode.. what is your opinion about that Sir?
Copper has very little to no resistance. The resitance is added with a resistor. If you take a 1/2 in inch of copper any gauge It will read 0 Ohms. Even a 28 gauge piece of copper will read 0 ohms resistance. It sounds like you have a meter try it
The 0.1 reading during your calibration of the meter is not the resistance of your leads; it's the result of the meter setting for your test (M=megohms). .1M would suggest that there are 10000 ohms in the leads. .Switch the meter to the smallest setting and then calibrate (short the leads) and I'm positive you will get a more accurate reading of 0.0. My text in parenthesis are for the layman reading the post. At one point in your test, you fingers were touching the pos and neg leads to asist in measuring the lead, and you are correct in that you will read body resistanse if both fingers are touching the leads, which is between 1K and 100K ohm, contingent upon other factors. I hope this helps.
James skippinhopper Hi James, I agree there are not 10000 ohms in a set of leads, which is precisely what I stated in my original post. However, your initial test was suggesting there were based on the setting (M) and the displayed reading when you shorted the leads (0.1). The meter defaults to auto-range when powered on. Manual range is available for ohms, V ac, V dc, A ac, and A dc. Depress the yellow button (center of the dial) momentarily to switch to Manual Range. Once in manual range, press the yellow button momentarily to change the range/scale. To revert back to auto-range, depress the yellow button for one second. Calibration should take place on the lowest scale and will read 0.0 ohms when done properly. I hope this helps.
hey sir just wanted to let you know thanks to your video i fixed my atv because it had a dead cylinder and i was about out the rear by taking it to a repair shop but when i saw this video , i did indeed had a bad spark plug and if you ever in mississippi or if i run into you by accisent ill be more than happy to buy you a cold beer.
Thanks Mr Mac Pender, tought me a lesson there all right ? No you did , now l know how to test a plug, do you show how to test the spark solenoid ? English Mik
I am new to having a lawnmower, is it normal for the plug to turn black and have to wire brush it, I did replace the air filter and figured that it was running too rich
As a mechanic at a small engine shop I would say go ahead and change the plug. Start with the easiest option first. Obviously this solution (checking to see if the plug is good or bad) is good for people at home, however if you bring it into a shop you can't expect your mechanic to do this. We are working on flat rate and we aren't going to waste the time testing this. My biggest issue with this method is that it leaves lots of room for error and human mistake. But to each his own! Only my personal opinion and so long as your unit runs whatever method works for you is perfect!
I enjoy the videos!
+avery9997 Thanks I am self taught with an electrical background. Thanks for being kind. Everybody should film themselves for a few videos.
I agree. Cost wise, it makes sense to just replace it. My 4-wheeler suddenly won't start and I'm replacing gas, spark plug and filter just as a default (one at a time to determine where the fault lies). It's only a year old and has never been ridden hard so it can't be anything TOO bad (I hope!). But this video does help to explain just what a spark plug is and does and how you can identify issues. If your problem doesn't lie with the spark plug itself but in the wiring (or worse) at least this can help to narrow down any issues. Thanks for the video, mate!
+Tennethums1 Yes I am on a tight budget. Thanks for the comment.
@avery9997 We all know (sadly) that every mechanic (at his own garage) are heavy eater $$$
That's why THIS KIND OF TIME WAISTING is at the hand of every newby who try to repair is thing by himself. (At 18-30$ each plug uhm...) *Try to keep your "secret" of succes in your garage mister The Mechanic ; )
Good rant. Years ago I read that spark plugs on magneto systems almost never wear out. Most of mine (not auto) are original; 30 - 40 years old.
+L Malino Thanks!!!
@@bacilluscereus1299 The R-type of spark plug is there for ONE thing.... to cut down the amount of current flow thru the plug which reduces the EMI that interferes with wireless devices. If the plug needs regapping, the gap has widened because of erosion (?)
Thanks for sharing your experience and knowledge Mr. Pender none of us were born with the answers and some just fake it to take our money. Your effort is a cut above.
Thanks a lot.
I totally agree with you. In 40 years of owning power equipment I have only had to buy maybe 5 plugs. It’s just like the 3000 mile oil change, totally ridiculous nowadays.
Thanks Andy
You're right. I've been mowing lawns on and off for 40 years and have never changed a sparkplug on a mower, strimmer (US: weedwacker) or chainsaw. The mower/strimmer/chainsaws rust out or fall apart before the plug needs changing.
Fuel filters on the other hand often need changing. Pull cords & recoil starters too. Carb/diaphragm occasionally.
I have a multi-meter so I'll try this, my mower is not starting as well as it used to - although I expect it is a fuel related rather than electrical. Thanks Bruce ;)
I had an old tecumseh mower for 25 years and I have a double lot and never put a spark plug in it. You are right.
You one of the lucky one, Last summer has replaced a coil of the Stihil Fs 90 , that only used less than twice Years ago, (because it too heavy, my sister put it away, get the electric. ) give it to me last year , installed a new coil & a new plug, start like a charm, last month it’s dead after 15 minutes run , installing a new plug ,it start up in first stroke. ? ? ? 😇😰
I was just cruising the CZcams for information on the air filter to my tiller. It's misfiring and I haven't had it running since last year. I'm no mechanic, I learn as I go. Too poor to afford to pay someone. I was wondering if my spark plug was bad and was going to replace it first. Thanks for this information. I just bought a multi-meter to work on my washer (got that running). I can use it to test the spark plug on the tiller now. Thanks for the information.
Good for you. Give it a try.
Thanks Bruce for that tip, been a mechanic for a long time and never heard of that.. ie: spark plug ohm test.
Appreciate, I'm never too old to learn something.!!
Michael Noel No thank you
Michael Noel As I mentioned below to remove any confusion. no--- I want to say thank you for replying to my video. I have more electrical experience in my life which I have brought into my mechanical knowledge.Bruce
You can only test a spark plug with the plug gap under max compression of the engine say 180lb/sq inch; The spark must overcome the densly compressed air !!
right!.... i'm with you now.... excellent, i couldn't figure out why when i put the spark plug to the engine block why i was getting a spark from the earth (the 'L' shape bend at the bottom of the plug) to the engine block, but no spark between the two contacts in the middle and why the engine wasn't firing up, starting, or running, so me plug must be knackered then because it's leaking if i think i'm right in saying after watching this then....
Sounds right.
yeah changed the spark plug works perfectly fine now, engine starts first time, no problem at all, that's the first time i've ever known a spark plug to ever fail like that, very unusual.so cheers for that.👌👍
Your video identified my problem today. Electrode looked good and gap was ok but plug was leaking voltage to ground. I learned something new today. A big thanks to you.
That is so cool. I use my meter once a week at least.
Very good, thank you. On 2 cylinder engines, after plug cleaning, I swap them around to confirm that any problem is not plug related - might be plug wires, coil pack, or other issues. I note the "Side" with the issue...
Great tip!
Nice tutorial, I 100% agree with your rant on people replacing plugs for no reason. I find maybe 1 in a100 or less machines actually need a new plug, and that's with all the machinery I service. Most are just dirty or carbon fouled. A quick heat up of the electrode with a blow torch and they are like new. I made a video on just cleaning these things.
Yes that high resistance between the electrode and ground is like a short to 13000 volts. but not many plugs get to that point. most are just fouled with carbon on the outside
Me too... I've worked on over 200 machines...I've bought maybe 12 spark plugs in my life. Wired brush the crap off. I agree with Bruce.
@@BrucesShop I keep all of my replaced plugs for use as swap outs.
I do they same thing ,except I don't have a torch to clean my plugs. I wire brush them until they look new again. A lot of people don't even know how to repair a lawnmower
So glad you typed in the word “conductivity”. It made so much more sense after that, instead of calling it resistance.
I understand. The ability to conduct. I worked in the "FIELD" LOL
True. I run mowers weed wackers, dirt bikes, outboards, cars, 2 and 4 stroke bikes. In the past 20 years I've never had to change plugs. I give them a clean, gap them, test them and re-install. Good as new! Thanks heaps for the video.
Some folks don't like this video but I am happy you agree. Just think of a car that goes 80,000 miles on a set of plugs.
i agree i have an old torro snow blower has its original plug since 1987. god i wish stuff was as good as it used to be.
Some stuff is better than it used to be. Car only lasted 100,000 miles when I was younger now they go at least 250,000
I agree, I only replace plug if customer insists on or want top dollar for a unit for sale. Looks good with a fresh plug in if old one looks crusty. Thanks Bruce
Totally agree
Thank you for a great video. Sometimes carbon buildup cause that high resistance to ground, clean it with a wire brush and it can be reused.
You absolutely right. Just measure them again after cleaning. I think on one engine i dropped a piece of wire from the spark plug into the cylinder and wrecked the engine. Always a learning experience.
I 💯 percent agree with you. I thank you for your video. You taught me a simple way to check a plug.
I usually let it run until the engine dies then replace it. Now
I have a way to verify it’s bad. Thank you so much!!
THANK YOU. I have had some push back on this video, but anyone with some electrical knowledge gets it. Thanks again.
kool... watched your video, then checked my generators plug, bought a new one, installed... gens running normal again... so thanks for your vid.
+John Kajfes Good for you. Thanks for watching.
Totally agree with you..but good to understand how to test if good or bad..Thanks again for keeping it simple.
New subscriber,good stuff.. 11 years on my toro 6.5 mower with the original spark plug and still starting and running strong.. Its all about maintenance and good gas habits.
Yes maintenance is the key.
Bruce
saltwaterwop Thanks for subscribing!!!
I tried to make the day without learning something new today.And you just ruined that.Lol but i love your vid and well explained.Thanks man.
You make a good point about the meter probes picking up resistance from your body.
Keep fingers back on the insulated handles, let the spark plug sit on a non-metallic work bench, or a block of wood if it’s metal.
You understand. Thank you.
nothing wrong with being frugal, excellent video helped me out....thx
+Hugo Avila Well thanks for watching.
Yep, I have never changed a spark plug in any of my small equipment, chain saws, log splitter, roto tiller, lawnmower, etc. Clean, gap check, test and use. 👍
Exactly Thanks
I have an old Snap on spark plug tester and cleaner. This is a big unit, probably well over a foot high and over a foot in length by another foot deep.To clean you use the silica/sand under air pressure. To test the plug you used just the clean air button to see the plug firing in the unit. It produced varying degrees of compression in the unit. That way you could actually blow out the fire in the plug if the plug was faulty. I used it many times over the years to detect a bad plug which btw wasn't that often. In those days of ignition points you could buy a single plug instead of a whole set..
That is interesting Thanks a lot.
Looked at a number of videos but it finally started to click here. Ariens Snowtek 20, comes with a LCT 136, worked last year but I needed the electric starter to start it. Would not start this year in prep for winter. It comes with and LCT recommends a Torch F6RTC, well I was getting about 4K electrode to ground but I found when I moved the electrode slightly I got zero ohms, at this point I carefully moved it to the snow blower and wallah Spark! I'm not sure how it is shorting but is is. 50 plus years and never saw a spark plug that would not work. What I saw here is that some do not work. It has to be pretty rare? This one is getting hung on the wall.
Yes the carbon inside the porcelain gap can conduct but if they are cleaned most of them can be revived as you say. I reuse plugs all the time and have only had a few that are duds.
Thanks for keeping it simple. I'm going to check my spark plugs as well. I even have a Fluke model 73 to check them with that I just bought. So far, it's a keeper!
Good luck! Fluke makes great meters
Omg my father in law and I have been trying to fix my generator for three straight days. This video helped us fix it in the time it took to test the plug and drive to AutoZone. Thank you sir!
Perfect
Bruce when testing the electrode with your ohm meter fine. But mate unless the electrode has a dead short to ground an ohm meter will not pick it up. Really to test between the electrode and ground you need an insulation resistance tester (megga ) which puts a high voltage between the electrode and ground and you will see if there is any breakdown in insulation. Which would not be possible with a continuity tester. The high voltage on the ignition system will find any weakness in the insulation between the electrode strode and ground. But still a good informative video .
Good vid. Most folks don`t have or don`t know how to use an ohm meter but, one doesn`t need a high dollar DVOM to check a plug. A cheaper analog, sweep type works fine. Least now, most can at least remove their plug from their "parts changing" list for a no start.
Right. I have 4 meters. A good one you saw. @ cheap digital and an old polarity sensitive analog. Thanks
👍Totally agree. I find it funny when folks drop off their mower and the very 1st thing they say is they think the spark plug is bad😂😂😂 Most common issue around my neck of the woods is a dirty clogged carburetor. Thx for the video.
I am sorry .I am getting so any comments from you I don't have time to answer them all. i am doing 200 comments a day now as I have almost 40,000 subscribers. Plus editing and the work in the shop. Sorry buddy
@@BrucesShop - Hey man, no worries! I just figure if a good CZcamsr puts out good content then the subscribers should do our part by thumbs up & leaving a comment. I’ve heard it helps out a lot. (Algorithms and such) It’s always nice to hear from ya however it’s understood & no reply needed. We’re all here for ya in effort to grow your channel & show appreciation for the video help that you provide.
Take er easy my Canadian friend 👍
(Ol KY 🇺🇸 boy here)
@@majorpayne5289 Thanks for that.
Hey, thanks for that tip, it never occurred to me to ohm out a spark plug! That's going to be pretty handy.
And I agree with your rant! I think it's mostly people that don't understand trying to convince themselves they know about a subject. Mower doesn't start, must be the plug; TV doesn't work, must be the picture tube (Conventional TV obviously); vintage radio doesn't work, must have a bad tube; car won't start, check the oil. etc, etc, etc.
Right. Thanks for watching
Now I completely agree with you on everything but depending on the aspiration of your vehicle (turbocharged or supercharged) will determine how much you should change your spark plugs. My mustang is turbocharged so i have to be spot on with my maintenance and repairs.
These are lawn mowers.
@@BrucesShop i meant to reply to someone🤦🏽♂️
I have a spark plug from...somewhere around the 1900s- 1940s
great information, i try to tell my customers when they bring me one for a tune up that i can throw the plug at it but its not always necessary and they usually opt to replace it anyway even if its good. i never thought to ohm these out, i always just wire the bail and pull the cord to check spark on the block with the plug pulled. this looks much easier, another great video. thanks for sharing
Thanks for your comment.
Thank you resurrected Robin Williams !!!!
Thanks LOL nanu nanu
I know a guy that every time something want start . He says it's the plug and that's not true I agree with u 💯
couldn't agree more, the spark plug that is on a new lawnmower will usually outlive the deck. the youtube ranters will say ... "they are only a buck"; problem is, they are waaaaaaay more than a buck and have been for years.
Right and I clean quite a few around here in my small budget shop.
I just replaced the spark plugs on my Ford fusion hybrid after 182k miles! The electrode was worn to a small nub, but the car never showed signs they weren't working. Less vibration after replacing then though! Iridium tips on the new Bosch plugs.
Thanks for the great story.
You seem very very knowledgeable about the mechanics of the machines that comes in your shop as well as the electronics of the machines. Spark plugs , coils etc. I would love to see you do a video or videos if you would on say trouble shooting the electrical aspects of the machines. Example. How to check a coil, spark plugs, safety switches. E t c I would love to learn more about it from my favorite small engine mechanic here on you tube.
Thanks. I will slow down on the next electrical repair.
I con cur with what you feel... thanks for this video!
+Peter Andolfi You bet. Thanks for watching.
Thanks for getting back to me, I'll check out my plugs, like you showed
Great
thank you sir for the video. helped a lot. believe I'm having issues with a spark plug currently on a small engine with only about 10 hours of use. however it's a crummy Chinese knock off spark plug and everything else I've looked into is checking out. good fuel, air cleaner. clean etc so slowly narrowing down the issue to hard to start motor. it's practically new so wiring and such all seems to be fine checking current on them as well. again thank you for the video.
+Mitchell w You are welcome.
Very good and thank you but on the "working" plug there is still no certainty with this test. The volt meter only has maybe nine volts across the leads while in normal working conditions the plug runs about 20,000 volts DC and at a way higher temperature. To really measure the internal insulation effectiveness to ground at that temperature would be the definite test. In any case the test shown here is to eliminate the most obvious bad plugs for sure. Thanks again.
I get it but it does measure Meg ohms. Great comment. Thanks I mean it.
BTH1 That is what I thought I heard this is KG5JWU. I learned what you are saying about 16 years ago when I was working on my old 74 Bug. Once I learned what you are talking about I stopped replacing plugs. I would check wires for oms = 1 per foot. I also made sure my gap ( points ) was good and timing was set ( gap plugs too). After I learned that I stopped spending money on ignition components over night. I went from spending a few hundred a year on parts to nothing. That bug cost me $500 a year including gas. Once I learned your secret. This gen will never understand.
Thanks a lot.
You're Welcome!
Thanks Bruce! I know I am guilty of this habit, but no more!
Thanks for watching RM P
I have walk behind string trimmer that is 15 years old, 4.5 hp B&S engine which has a J19LM spark plug which has never been changed.
They are the greatest especially the older one. Clean it and keep going.
Thank you, this was a huge help in troubleshooting. After testing my spark plug it showed it was bad, bought a new one and my lawn mower fired right up. Crazy, the original plug was less then a year old. I was hesitant to buy a new plug cause the original looked good.
+ThePlynn7 I have had some that looked so bad and were OK and like you another would look perfect and is toast.
Thanks for the simple explanation and demonstration! I will confess as one who is guilty of changing spark plugs to correct an ignition issue. I will use this test from now on, and look forward to more videos! Dan
Thanks Dan. Not everyone gets this video.
Robin Williams does small engine videos now?
I have heard that before.
:-)
dead ass haha
Rip robin williams
Lol
This didn’t age well
I get what you mean. I just replaced the spark plugs in a car after the previous owner ran them for 200,000 miles, they worked but the electrodes were pretty much not there.
If it won't start it is usually the spark plug. The heating up and cooling down eventually cracks the ceramic dielectric. That said my 25 year old snow blower has the original spark plug. It is usually bad gas that causes problems in small engines, I put gas treatment in the gas I use for my small engines. My snow blower usually starts on the 2nd pull. I may have to replace it soon because the front end is breaking up.
Right!!
Peter B. thanks for the info-tip
Yes, that is a good way to tell if a spark plug is bad. One "BAD"test that many will do, is that they will remove plug from engine. Attach the high voltage lead to it, and then touch the base of the plug to the ground of the engine while pulling the starting cord and watch for spark at the gap. If they see a spark, they determine that the plug is good. But some times a bad plug will not produce spark when under engine compression!
+service1956 You are right.
The colour of the spark should be blue. Orange colour means bad plug.
I saw another video that suggested 5k is the normal impedance for a resistor plug. 20K seems quite high. I had a mower with a plug resistance of 18K, the mower wouldn't start. I replaced the plug, it started fine.
Right. The plug itself may not have an R in the title like RJ19LM That one has a resistor J19LM does not. Thanks for the comment.
Maybe a confusion with your term leak through... I think what you're trying to say is that the carbon shorts the center electrode to be grounded portion of the plug. Other than that it was a good presentation because I already understood what you were trying to explain. The resistance varies on the condition of the plug or how carboned up it is...
Yes it is easy to get into the details when you understand eh!!!!
Nice technique, I will check my spark plug next time thanks for your videos
Thanks for the tip. I personally have never had to replace plugs unless someone replaced them with the wrong type.
P.S. On the other side. I bought a truck from my dad with 250K miles. I decided to check the plugs and when I got them out they had a gap the size of a match head and a half or more and the electrode was below the base of the threads, nearly flat on the ceramic and round. and the thing still ran fine. Ford 1994 F150 six. Red.
Yeah, and many people get charged for a “tune-up” on their small engines, consisting of a spark plug and air filter, blade sharpening....all they really needed was a blade sharpening and maybe CLEAN the plug, probably clean and replace the air filter if you’re in a dusty area.
When I was growing up in Michigan, we had a nice lawn and didn’t get much dust stirred-up....air filter lasted a long time.
Now, I get lots of dust, air filter gets dirty in a hurry.
Yes Plugs last 100,oo km's on a car. If cleaned they will go a long way on a yard machine.
If you're going to clean & re-use a spark plug you can get more life out of it if you not only clean it with a wire brush but file the contacts so they are both flat and aligned. I used to do this with a points file but any small metal not-too-rough file will do. Also re-gap the plug but only bend an electrode once or twice so that it doesn't break off in your engine.
Good advice. thanks
It depends what yoyr fixing. For myself ill keep the plug till I have problems. However if im fixing or tuning something up for someone else I would replace it for preventative matanence.
Good point
Spot on!!! Use your brain instead of simply being a parts changer.... I like it!
Thank you.
My pet hate is when you hear someone say I will replace this part " just in case", in case of what ?
I would recommend using a megger to measure the leakage across the ceramic on a spark plug as this is more effective for finding insulation breakdown as they use 500- 1000volts when testing. Also DO NOT USE A WIRE BRUSH TO CLEAN THE CERAMIC CORENOSE of a spark plug as this leaves a metal coating on the ceramic and will cause the EHT to track across it to ground then you have to buy a new one. You could try a sandblasting spark plug cleaner but you must make sure all sand traces are removed from inside the plug before 're using it. You do not want any sand to end up inside your engine.
Thanks. Yes 1 M ohms is like a short to 20,000 volts
Thanks for this video 👍
Thank you for watching.
thanks bruce i always learn from your videos very helpful
What a great video, perfectly done. Thank you so much for your valuable information! Have a great day!
homebuiltindoorplane ii
Tested the plug, it was bad. Thanks, good video.Up and running again.
I find it amazing that 2meg ohms would short out a plug but t is thousands of volts in the high voltage spike.
Air filter, air filter, air filter, oil change every season, fuel filter every 4 seasons and then after 5 seasons check and clean the spark plug if your fuel consumption goes up because your voltage used on the lawn mower type system in general is so low that electrode wear is minimal. But your air filters and oil filters should be maintained every season as needed.
I agree.
I have a quick and dirty test. If you hold the plug in you hand and jump backwards, it’s good! Verifying dielectric air breakdown exceeded 3,000,000 V/m. Meaning good spark, don’t need no fancy meter.
You have been in school too long. I would say between 13,000 and 20,000 volts and I won't hold the plug. haha
That would be a little less than 3,000 V in free air for a spark gap of 0.035", STP. Inside a cylinder head, different ballgame and you're right.
Thanks
I have never bought a air filter . I use foam packing material. When it gets dirty just was in warm soap and water.
Interesting! Thanks very much for this knowledge!
Glad you enjoyed it!
Mr. Bruce if interference is not an issue from the spark plugs in my riding mower, is there an advantage to use resistor plug? If I interfere with no one there is no use to resistor plugs is there? Thanks for this interesting video!!
Resistor plugs were made to reduce radio interference.
Thanks for sharing your video on CZcams I never knew about using an ohms tester. People here my bitch about what you have said but as far as I'm concerned I have learned a lot and I sincerely thank you for it!.
Believe it or not I think that doing this will definitely save me money in the long run because I have been spending far to much money on those damn spark plugs for sure!.
However since watching your video I now know how to test them spark plugs and I sincerely appreciate your video and for sharing.
Thanks for the great reply.
Joejava SIRS. YOU ARE ..ABSOLUTELY ...CORRECT...OHMS,RESISTANCE,VOLTAGES..ALL APPLY WHEN TROUBLE SHOOTING...ANY CIRCUIT..(automotive, lawnmowers,lighting circuits- these are ‘DC circuits’)...knowledge is amazing...makes repairs easier and satisfying thank you for sharing...KEEP-ON-WRENCHING..fellow UTUBERS
i used to replace them in all equipment i worked on but now if they work i just leave them alone if they work no point in replacing them unless there bad
Yes me too. thanks for watching
You really need a Megger for a valid insulation test.
If you have a GOOD DMM (which can read to 40Mohm) lying around, that is ALL you need to check the plug.
E/I. Great video. I've learned something. Thank you
Thanks a lot sir !!!!
If you don't have a omh meter and want to know if a plug is goo or bad, just take the plug out, leave the plug wire connected, sit the plug on the engine anywhere so that it is grounded, and then crank the mower a few spins. If you see the plug making a spark, then its good. If not, it could be a broken, or corroded plug wire. A test light will tell you, or just lay the end of the wire close to the engine and see if fire jumps to the motor, or lights the light.
I would caution one when checking a plug that way. Though one can check for spark that way, the cylinder can spray fuel out that hole and ignite and now one has a fire on their hands. I've seen it many times. So be careful.
Yes resting the sparkplug on the engine is hard to beat as as a simple "acid test": works/doesn't work. However, Bruce's technique should also detect marginal plugs that will work at least sometimes but just not as well or reliably as they should.
I bought a sparkplug test light but I found it didn't work - at least not well - with the mower, I was disappointed. Probably intended more for cars & motorbikes. Just sitting the plug on the engine block worked better.
(Thanks for the fire hazard warning George ;)).
I just did that and was getting spark. So i spent hours cleaning out the carb, adjusting, cleaning again, and adjusting again. It would start to fire up sometimes and then die. I tested the plug with a meter the way this guy was saying and according to the test it's a bad plug. Unfortunately the auto store here doesn't have the plug i need.
i have a spark plug thats over 50 years old and still good thay just dont make them to last now
You are absolutely right.
Colin Wood nothing in america is made to last long.
The real problem is that the companies that makes them do this deliberately so your spark plugs end up falling. It's all a Monopoly, I remember when I was a kid spark plugs back then worked great and work forever they don't make them like they used to they make them now to fail on you on purpose make them ground out and you loose Park faster and basically Bruce is telling us in the video is very true because this shit happens a lot and they just don't make them like they used to back in the day but for that reason they're doing that because they want you to buy more of them it's all in Monopoly like I said.
Good Video 👍 I have lots of to choiche from on my multimeter on ohm. What i gona set it on? 20 k Ohm ore 200 Ohm? On the multimeter
I would use 20K The important one is measuring between the electrode inside the porcelain to ground. Use a high reading 20K or higher.
great video sir
Thanks old video
Excellent information! Thank you so much for sharing.
You are so welcome!
great video to watch.
Thanks for the visit
Yes, this is fine when in a pinch and it's your own equipment. Not the best practice for a customer, better to simply replace with a nice new properly gapped plug, even then you should still do the quick test even of the new plug for a customer. just my view. enjoy your videoes
You are right my channel is all about saving money.
Great video! Thank you for helping me fix our lawn mower.
a little electrical knowledge is great.
You are So Gentleman.
Love From Afghanistan
Thanks
One thing I don’t understand why the manufacturing the resistor spark plug ? ? ? For lawnmower !
It is to reduce radio interference on everything from cell phones to FM radios.
Thanks for the tip. Be watching !
Right on Thank you for watching.
On target with everything you said, my friend!!!! Thank U for a great video!!!
You should see some of the comments.
Good informative video, however at 4-15 should you not be saying " adequate resistance to ground"? not " no resistance to ground"?
Oops, just seen your correction, ie ,Conductivity. Thanks.
My ride on mower is 18 years old & never change the spark plug it's at 280 hours.(17 HP Briggs and Stratton intek)
That is cool!!!
but there are expensive original spark plugs that has a little copper from inside should give reading between 2000 to 6000 ohm when we measure the tip and it's end without touchingthe ground electrode.. what is your opinion about that Sir?
Copper has very little to no resistance. The resitance is added with a resistor. If you take a 1/2 in inch of copper any gauge It will read 0 Ohms. Even a 28 gauge piece of copper will read 0 ohms resistance. It sounds like you have a meter try it
The 0.1 reading during your calibration of the meter is not the resistance of your leads; it's the result of the meter setting for your test (M=megohms). .1M would suggest that there are 10000 ohms in the leads. .Switch the meter to the smallest setting and then calibrate (short the leads) and I'm positive you will get a more accurate reading of 0.0. My text in parenthesis are for the layman reading the post. At one point in your test, you fingers were touching the pos and neg leads to asist in measuring the lead, and you are correct in that you will read body resistanse if both fingers are touching the leads, which is between 1K and 100K ohm, contingent upon other factors. I hope this helps.
Michael Karnish There is not 10000 ohms in the leads! And that is an autoranging meter.
James skippinhopper Thanks
Good video, Thanks!
James skippinhopper Hi James, I agree there are not 10000 ohms in a set of leads, which is precisely what I stated in my original post. However, your initial test was suggesting there were based on the setting (M) and the displayed reading when you shorted the leads (0.1). The meter defaults to auto-range when powered on. Manual range is available for ohms, V ac, V dc, A ac, and A dc. Depress the yellow button (center of the dial) momentarily to switch to Manual Range. Once in manual range, press the yellow button momentarily to change the range/scale. To revert back to auto-range, depress the yellow button for one second. Calibration should take place on the lowest scale and will read 0.0 ohms when done properly. I hope this helps.
Michael Karnish Her was measuring 0.1 ohms not 0.1Mohms
So how to tell if the spark plug has lost its efficiency but its still working? Thanks
hey sir just wanted to let you know thanks to your video i fixed my atv because it had a dead cylinder and i was about out the rear by taking it to a repair shop but when i saw this video , i did indeed had a bad spark plug and if you ever in mississippi or if i run into you by accisent ill be more than happy to buy you a cold beer.
Good for you for fixing it.
I changed last time on my Matrix 14 year a go, but on other cars i need to change it every next year.
Yes plugs last a long time in cars eh !!!
Thanks Mr Mac Pender, tought me a lesson there all right ? No you did , now l know how to test a plug, do you show how to test the spark solenoid ?
English Mik
Do you mean the coil ??? Different world over here.
I am new to having a lawnmower, is it normal for the plug to turn black and have to wire brush it, I did replace the air filter and figured that it was running too rich
Well it should take quite a few hours of running time to turn black.
Guilty as charged...awesome vido
OK