How do I check whether there are cracks in your spark plug wires

Hello and welcome back to our series on automotive tools and how to guides for the new weekend warrior auto mechanic. This isn’t meant for the professional, but rather the average Joe who is looking to get his hands a little dirty on the weekends. In the past, we have covered a lot of tools but in today’s article I’m going to cover how to check your spark plug wires for cracking in the insulation. The spark plug wire carries the electrical charge from the ignition coil down to the plug where it jumps the gap between the electrodes and initiates the combustion process. Needless to say they are critical to the internal combustion engine, and problems with them can cause operational issues, lost gas mileage, and great emissions output.

Here is a real easy way to check them. Ideally you will want to do this in complete darkness. Since that’s often not possible, do this at night with as few surrounding lights as possible, none if possible. Raise your hood and with your car in neutral or park let it run with the emergency brake on. You will want to look in the engine bay until your eyes adjust to the low light. If your ignition wires are cracked, you will probably see little sparks or arcs of light from the spark grounding out against the engine.

If you still don’t see anything and suspect your plug wires of being bad, you can lightly mist the area around the wires with water out of a hand pump spray bottle like you would use for your hair. If you still don’t see anything, you may have a cracked wire but you won’t be able to find out without removing all of them and physically inspecting them for cracks. However, 9 out of 10 times, this method works just fine.