4 Spark Plug Replacement FAQs
Let’s explore some more about spark plug replacement through these four commonly asked questions:
1. Why Do Spark Plugs Need Replacing?
Every time a spark jumps the gap between the center and ground electrodes, it burns off small amounts of metal from each electrode. And this gap continuously increases as your vehicles spark plugs constantly fire during engine operation.
With time, the spark plug gap grows so much that the spark can longer make the jump.
In other words, your spark plug fails.
You’ll then experience dips in fuel economy, slow acceleration, and rough idling.
2. How Often Will I Need To Replace Spark Plugs?
Your spark plug’s lifespan can range between 20,000 miles and 100,000 miles (for a long life spark plug).
It varies depending on the:
Consult your car owner’s manual for more clarity on when to change spark plugs.
However, if you’re looking for a general rule, most manufacturers recommend changing spark plugs every 30,000 miles.
3. How Do I Replace A Bad Spark Plug?
Spark plug replacement can be pretty challenging on some vehicles.
You may need to remove the engine’s upper plenum or intake manifold before reaching the spark plugs. Moreover, you can have difficulty accessing and removing components like the ignition coil or spark plug wire.
Not just that.
If you do a bad job with the spark plug replacement, you can lead to expensive engine repairs.
That’s why it’s best to let a professional mechanic at an auto repair and maintenance shop change your vehicles spark plugs.
That said, here’s what usually happens during spark plug replacement:
Your mechanic will first gather the tools/parts required — new spark plugs, spark plug socket, ratchet, torque wrench, spark plug gapping tool, anti-seize lube, dielectric grease, etc.
After that, they’ll:
- Remove the engine cover (if your car has one).
- Disconnect the ignition coil connector.
- Remove the old spark plug using an appropriate spark plug socket.
- Clean the spark plug hole to remove debris that can damage the cylinder head threads.
- Gap your new spark plug according to manufacturer requirements if it’s not pre-gapped.
- Apply a thin layer of dielectric grease to the spark plug boot.
- Install the new spark plug.
- Tighten the new plug with a torque wrench based on the manufacturer’s torque specification.
- Reinstall the ignition coil connector and engine cover.
- Fire up the car and ensure everything works as expected after installing the new plug.
4. Do I Need To Replace All The Spark Plugs?
Ideally, you should.
Changing spark plugs lets you prevent situations like engine misfire, bad gas mileage, etc.
If you’re replacing only those spark plugs that have gone bad, each spark plug in your engine will have a different replacement cycle. Consequently, you’ll need to spend more effort and time with repairs whenever you encounter a spark plug failure.
Moreover, your engine works best when all the spark plugs have similar performance levels.
For instance, if two spark plugs in your six-cylinder engine have one level of performance and the rest have a different level, it can cause the engine to go out of sync.
In short, replace all your spark plugs at once to ensure a consistent level of performance.