How to Test a Spark Plug In One Minute

welcome back guys it's the tightwad and today I'm gonna be showing you how to test your spark plugs to see if they are still good or if they need to be replaced and I'm gonna do a little bit of explaining about the parts of a spark plug and then I'll show you how to test them the testing actually takes less than a minute to do so if you have a multimeter so a spark plug always has a number on it and this one is an RC one - why see at the bottom that's the type spark plug I need for my rotary tiller that I used to tilt my garden every year and this one went bad so I went to the store and got a replacement and this one actually shows a different number here BK r 5e but on the packaging it shows the champion RC 1 to YC so it matches my original number this is just a different brand so it could potentially have a different number but it will have any that it matches showing on the package if you have a spark plug that has an R and the model number of it that means that there is a resistor inside the spark plug resistors are made to keep it from interfering with things such as a car radio or a camera so a lot of times they're not found in spark plugs that are used on lawn equipment alright so in a spark plug you'll see that there is a porcelain piece here this porcelain police actually extends all the way through to the back of the spark plug and you can see it come out on the tip back here encasing the end of the piece that runs all the way through the middle so there's a metal piece that runs from here all the way to the tip here and that piece has a tendency to break crack and go bad to test for ohms you need to change your multimeter to the ohms setting all mine it's indicated by the letters o H M on some multimeters it's indicated by the horseshoe symbol upside down horseshoe or Omega if you're familiar with the Greek alphabet and I like the 20k setting so anything between 10 and 20 K is fine if you don't have 20 K you can always go up higher and now we're going to test these spark plugs so to test a spark plug for resistance using the home setting you're going to touch one of the leads to this end of the spark plug and remember I said there's a metal piece that goes all the way through the center of the spark plug and there is a resistor inside the metal piece and then the other end of the spark plug has this little tip on it this tip is where I want to touch my other lead so I have one lead on the bottom down here and one lead on the top and you actually need to touch the top of that piece not the side of it to get an accurate reading so I'm going to touch my leads together to start and you'll see that I get a reading and then it zeros out letting me know that my multimeter is functioning properly so I know that my battery's not dead and there's nothing else wrong all right I'm actually going to use the side of this piece down here because it keeps the whole spark plug from rolling around and then I'm gonna touch the top up here all readings of ohms I mentioned are actually in thousands so when I say 6 ohms I'm referring to 6 thousand ohms you'll see that I get a reading of 6 ohms exactly anything between 5 and 15 ohms is pretty normal for a spark plug made for a small engine such as most of the things used for your lawn equipment at your house what I should not get is a reading anywhere else on this spark plug so if I touch any of these other parts I should not get any resistance if I got resistance here that would mean that something is wrong where this metal shaft is coming into contact with this piece or it's somehow leeching through the porcelain getting to here indicating that it is now a faulty spark plug so we shouldn't get any resistance on any other portion of the spark plug except for the tip the metal piece here now that we know that one's good it was brand new I'm gonna test this old one that I removed from my rotary tiller so again I'm gonna start here and I'm gonna come up to the top and touch the very tip of this spark plug and I get no readings that means something between here and here is broken it could be the resistors gone bad or that there's a crack in the metal piece or a crack in the insulation but we know that this spark plug is no longer good because it didn't give us any readings one thing you do have to be careful for is if you have a dirty old spark plug it could have some carbon buildup so you need to take a wire brush and clean this tip of the spark plug or you can also spray some brake cleaner on it to get it nice and clean spark plugs with resistors typically have a higher reading of ohms than spark plugs without a resistor so this particular spark plug does have an R in it so we know that's why we have a reading of 5 or 6 ohms if it did not have a resistor in it we'd have a reading closer to 1 or 2 ohms if your spark plug does have a resistor and you get up into the 15 ohms range that could be a sign that your spark plug is starting to go bad anywhere between the 5 and 15 ohms range on a small engine style spark plug with a resistor inside should be fine to use if it doesn't have a resistor you're looking for anywhere from 1 to 5 ohms I hope you found this video helpful if you did give me a thumbs up and subscribe to my channel leave any questions you have in the comment section below if you want to see one of the other videos displayed on the screen right now just click them and they'll open right up on your device I hope you guys have a great day you

Channel: TightWadDIY

Views: 1,838,475

Rating: 4.8378172 out of 5

Keywords: spark, plug, sparkplug, plugs, test, testing, how to, diy, tightwaddiy, tightwad, tightwadrepairs, twr, twdiy, mower, wont start, wont run, check, multimeter, continuity, fluke, champion

Id: N6Ng-yhCeNs

Length: 6min 18sec (378 seconds)

Published: Mon Apr 08 2019