It may not be the most expensive part in your car and it’s definitely not the most exciting – but the spark plug (and wire) is unquestionably one of the most important. It’s that all-important last piece of the ignition system that every gasoline engine needs to operate. Neglect the spark plug and you’ll have an engine that misfires, starts hard, or breaks down altogether.
If you want to avoid getting stuck on the side of the road, knowing how to diagnose and repair spark plug wire problems is definitely worth your while. Considered basic training for any auto mechanic, it takes only a sharp eye and a few hand tools to get the job done.
Diagnosis: Spotting the Problem
You can’t fix a problem you don’t know exists, so step one of spotting an issue with spark plug wires depends on knowing exactly where to look for evidence. The wire is the vehicle’s energy transportation system – it delivers electrical power from the engine’s ignition system to the spark plug. Anyone who’s taken simple auto mechanic courses knows that when this delivery is interrupted, the engine stops working dependably. You’ll notice a rough and erratic engine idle or miss, which comes from incomplete combustion. If more than one spark plug wire fails, the engine will simply die altogether.
If the spark plug wire you’re looking at has been ripped right out of its boot – but is still safe to use – you don’t necessarily need to run out and buy a new set of wires. Any good auto technician training includes these basic steps to repair the wire and get your vehicle running smoothly once again:
Step One: Remove
Use a pair of needle nose pliers to remove the metal clip from the spark plug. Then, remove the other end of the spark plug wire from the distributor. Next, press the spark plug wire through the boot until it comes out the other end.
Step Two: Repair
Now that you’ve got the wire through the boot, use cutters to strip the rubber back a little. Leaving about an inch and a half of the black conductive material exposed. Then, fold that piece of exposed black material back along the rubber wire. Finally, slide the metal piece over the entire wire and squeeze it closed. Now you’re ready to slide the whole metal piece, complete with the spark plug wire, back into the boot.
Step Three: Restore
Using a little WD40, set the boot on the spark plug and press down until you hear it click into place. And that’s it! The spark plug wire will perform as good as new.
Replacing Spark Plug Wires “Caution”
- Make sure your car’s engine is cold before you start. Underhood environment can be very warm – only remove the spark plugs wires when the engine is cool to the touch. It can take a few hours for an engine to cool.
- Wipe off the spark plug insulator and distributor cap towers before installing new wires. Route the plug wires exactly as they were originally. To avoid arc-over, do not route wires of consecutively firing cylinders next to each other.
- A couple of things to keep in mind if you have more radio noise upon completion – (1) Metallic wire sets can radiate the ignition noise like an antenna. (2) Always check radio noise with the hood closed and latched. (3) Ensure the spark plug wires aren’t routed parallel to a sensor wire.
- Never clamp spark plug wires tightly or allow them to be pinched between the air cleaner and the distributor. The high voltage stresses will be increased at these points and hasten wire failure.
- Bundling of spark plug wires and wrapping them with tape. Pulling them through metal tubes or dressing them tightly against the engine, may make them look neat but can cause serious voltage losses and/or crossfiring. Changing the routing from the original OEM routing can lead to early spark plug wire failure.
