TESTING SPARK PLUG HOW TO

If you get a reading in this range, your spark plug works. A functioning lawn mower or small engine spark plug will read between five and fifteen thousand ohms on a multimeter resistance test.Īn example of what this will actually look like on the screen of your multimeter is: 5.00 (five thousand ohms) or maybe 15.00 (fifteen thousand ohms). Ohms are displayed in the ones or tens on a multimeter, but represent thousands. It’s important to do this the right way so that you have an accurate reading.ĭouble-check that your multimeter is turned on and is at the right setting, and then take a look at the reading. You want your multimeter lead to be resting at the flat tip (or top) of the electrode, not on the cylindrical side. The electrode is the metal part that barely sticks out of the porcelain sheath, not the curved piece of metal connected to the threads. This electrode is on the side of the spark plug that screws into your engine. Then, take your other multimeter lead and put it on the very tip of the spark plug’s electrode. I like to set the spark plug on a table on its side and press the lead on the side of the terminal so that it doesn’t roll around. Now take one of the multimeter leads and set it against the metal tip that the spark plug hood snaps onto (the terminal). Most multimeters will say OHM on them or simply represent it with the omega (horseshoe) symbol: Ω Set your multimeter dial to either 10k, 20k, or higher, in ohms. I think the trickiest part is being sure to use the right setting. Here I’ll describe the process for doing a resistance test in ohms.

TESTING SPARK PLUG HOW TO

Or, Test Spark Plug With MultimeterĪlternatively, if you have the tool, figuring out how to test a spark plug with a multimeter isn’t super complicated. Though the amperage is low and not fatal, you don’t want to learn what a few thousand volts feels like. Make sure the insulation on your pliers is in good shape, and don’t touch the spark plug with your hand. A healthy spark plug will produce a vibrant blue spark each time the motor turns.īe extremely careful when doing this. Now, you or the person holding the spark plug needs to focus on the electrode and look for a blue spark arcing when the motor turns. Since the spark plug is out of the engine, you don’t need to worry about the engine starting. One person needs to pull the starter rope or turn the key if you have an electronic ignition. This is where your extra set of hands comes in. With the spark plug grounded, the next thing to do is to turn the engine over. To do this, you just need to press the end (near the threads and electrode) against a piece of metal such as the engine block or mower deck. Then, grasp the spark plug by the threads or porcelain body with your insulated pliers and ground the spark plug. The following steps will give you a good idea of why.įirst, reconnect the ignition cable to the spark plug once you have the plug removed. To conduct a test for spark without a multimeter, I would recommend asking a friend or neighbor to lend a hand. Test Spark Plug Visually (Without Multimeter) One thing to keep in mind here is that you’ll want to be sure you have a good grip on the spark plug and gently twist it loose so that it doesn’t strip. Pop the spark plug hood off, secure the ignition cable away from the plug, and get your socket set on it. The process of removing a lawn mower spark plug is pretty straightforward with the right tools. I’ll go into depth about testing spark plugs both with and without a multimeter. Now that I’ve outlined the basic steps for how to test a spark plug on a lawn mower, let’s talk details. How to Test a Spark Plug on a Lawn Mower (Step By Step) Either get your hands on a new spark plug, or if your current one works, you can throw it back in the mower. Lastly, take the test into account and decide whether to replace or reinstall.You’ll either do this with a visual test or a multimeter. With the spark plug removed, the next step is to clean/wipe the spark plug off.The very first thing you’ll need to do is get your spark plug removed from the mower.Let me go through a very broad description of how to test a spark plug on a lawn mower before I dive into detail. Quick Overview of Testing a Lawn Mower Spark Plug An extra set of hands (if not using a multimeter).

Most of these tools are pretty common, and if you don’t have them already, they’re worth the investment. In order to give your spark plug a quick examination, you will need a couple of tools.

Oil leaking from the exhaust, oil reservoir, or crankcase.Įquipment You’ll Need to Test Your Lawn Mower Spark Plug.

The main signs that potentially indicate a bad lawn mower spark plug are: 5 If in Doubt After Testing the Spark Plug… You Might Want to Test Your Lawn Mower Spark Plug If…

Testing spark plug