When the spark plugs in your car malfunction, it can cause some serious inconvenience for you. No spark plugs, your car isn't moving at all. Luckily, getting new spark plugs it's not very costly at all. In fact, it's one of the more cost-effective repairs that you can do on your car. Some spark plugs can be as cheap as $10 each or even less. If you head to AutoZone right now you can find a variety of spark plugs that cost about $6.50. On average, you can expect to pay between $15 and $50 for spark plugs.
Spark plugs that cost $40 or more are not unheard of, but they're not that common, either. There is also likely little reason that you would need a spark plug that costs $60 or more. If you do find one priced that highly, there are almost definitely going to be cheaper alternatives unless you are driving an extremely rare, extremely high-performance vehicle. If a mechanic or repair person ever recommends spark plugs that cost that much money, make sure you look into what alternatives are available that should cost you far less.
If you're going to a mechanic to get your spark plugs replaced, the labor costs are likely going to be somewhere between $50 and $150 depending on a number of factors. Obviously how rare your car is might affect the kind of spark plug you need, and as with any repairs one mechanic may charge you far less than another mechanic even within the same town. Always make sure you shop around first to get the best offer.
Swapping out spark plugs is not a very time-consuming job, and any mechanic should be able to get it done within an hour for you fairly easily. It's possible that you may need more than one spark plug replaced in your car so that will also reflect the cost of the whole job. Each cylinder in your car's engine has its own spark plug, so a four-cylinder engine is going to have four plugs, a V6 will have 6 plugs and so on. If your car is still able to run, then not all of your plugs are bad and won't all need to be replaced.
When Should I Replace My Spark Plugs?
It's not necessary to wait until your spark plugs have completely failed to have them replaced. in fact, if you want them to keep working optimally, it's recommended that you replace your spark plugs every 20,000 to 40,000 miles.
If you have some higher-quality, long life spark plugs they won't need to be replaced this often. Iridium or platinum tip spark plugs can last for 60,000 miles all the way up to a hundred and fifty thousand miles. Your mileage will vary as they say, and if you drive a lot then obviously your spark plugs and every other part of your car will be subject to little more wear and tear and may wear out a bit faster.
What Do Spark Plugs Do?
Electric vehicles and diesel engines notwithstanding, your average modern car works the same way vehicles did nearly 100 years ago. The combustion engine burns fuel to create the power that gets the car in motion. Fuel and air are mixed in precise proportions in the combustion chamber in your engine. But before it can burn, the fuel needs to be ignited. That is the spark plug’s job.
As the name suggests, the spark plug creates a spark. A spark plug is connected to the ignition coil which transmits electricity to the plug. The electrical energy jumps the gap in the plug and that little spark is what creates enough heat to ignite the aerosolized fuel and air allowing combustion to occur. A plug in each cylinder of your engine starts the combustion reaction repeatedly while your car is in operation. If you have a 4-stroke engine operating at 3,000 RPMs, then you have 1,500 sparks per minute occurring. As you can see, a spark plug gets quite a workout in your vehicle.
Typical spark plug should be able to handle millions of Sparks before it breaks down. Most spark plugs have a copper core in them to conduct electricity. Copper is very good at that, which is why most household wires are made from copper. The softness of copper does require that it be coated to withstand the temperature that has to endure. Nickel coated copper is really common. Higher quality plugs will have chips made from metals like platinum and iridium which are exceptional at conducting electricity and also resistance to heat damage and corrosion.
What Can Cause a Spark Plug to Fail?
There are several causes that can cause a spark plug to perform poorly or fail completely. They can be slow processes to get started and tend to build up and become worse over time just due to the nature of how they come about in your car's engine. For that reason, they're not as easy to diagnose is something as obvious as a broken axle or even a flat tire. These aren't sudden issues that jump out at you. On the upside, it's not too hard to identify most of these causes if they are the issue at hand.
- Oil. Oil in the combustion chamber is one of the most common causes for spark plug failure. In time, oil will begin to leak into the chamber and can build up around the tips of spark plugs. As oil and dirt continues to develop on the plug it inhibits the ability for the spark to actually form, and therefore combustion is no longer possible or becomes inconsistent.
- Overheating. Spark plugs are designed to operate in high heat, but they do have limitations. If the timing in your engine is off for when combustion occurs, you can suffer pre-ignition which will greatly increase the heat in the combustion chamber. Also, if the cooling system in your vehicle isn't working properly then the engine will heat up to a higher temperature than it is meant to handle. While this may not destroy a spark plug immediately, exposure to consistently high temperatures beyond what it's designed to handle will cause it to fail much sooner than it should.
- Bad Gap. The tip of the spark plug is where the gap is located and it's this gap between two pieces of metal where the spark actually forms. This has to be sized precisely right for the spark to form correctly. The wrong sized gap will throw timing off and put extra stress on the spark plug. That can cause it to wear down much faster than other plugs.
- Carbon Build-Up. Overtime black, City carbon will build up on your spark plugs. This can come from any number of places in your engine. Anything from faulty fuel injector to clogged air filters can contribute to if you want to put Carbon on your plug. Just like when oil builds up, it interferes with the spark plug’s abilities to actually produce a spark.
How to Tell Your Spark Plugs are Failing
There are a few symptoms you can look for that indicate you may be having a problem with your spark plugs. Many of these issues can be caused by several problems in a car, but the process of elimination is the best way to diagnose many vehicle issues.
- Engine Misfire: Engine misfires are a very noticeable side effect of bad spark plugs. Because they're not sparking at the precise right time, your engine won't fire correctly.
- Rough Idling: Bad spark plugs can lead to some rough idling that you can both hear and feel. The car should be making a rumbling sound and it may even vibrate as you're waiting at a red light. It's a good indication that you should get the plugs checked out.
- Poor Gas Mileage: If your spark plugs are able to Sprint properly to start the combustion reaction at the precise time, then your fuel mix will not be optimized. You could have more fuel pump directly into the combustion chamber and you'll end up wasting gas overall. You'll notice this happens as your gas mileage starts to decrease, requiring you to head to the pumps more often.
- Poor Acceleration: As we've mentioned, your spark plugs have to fire thousands of times every minute to keep your car functioning properly. When they're failing because they're worn down or covered with grits and oil, the spark will not be consistent. That means you won't be getting the kind of power you're expecting, and your acceleration can suffer as a result making your car seem sluggish and slow.
- Rough Starts: If your spark plugs are not functioning properly then when you try to get your car started you may have issues producing a spark and let's go to create problems. You may have to try a couple of times to get the car to start properly.
What Happens if I Don't Replace my Spark Plugs?
As you can see there are a wide number of symptoms associated with poor spark plug performance. If you know your spark plugs are failing and you don't get them replaced, these symptoms will continue, and the situation will be exacerbated. You can expect that all of these issues from the poor acceleration to the rough starts will get worse. Engine misfires will become more prominent and, in time, you can expect that your car simply will not start at all.
For a part that you can pick up for under $10, it's not worth avoiding getting your spark plugs replaced the moment you realize that they're not functioning at 100%.
Spark Plug Replacement DIY
When you take your car to a mechanic to get the spark plugs replaced you can expect to pay between $50 and $150 just in labour costs. You can save yourself that money if you want to try replacing the spark plugs yourself. It's not that difficult a job to do on your own, and there are many guides that you can find online to walk you through it step-by-step. They're even some very clearly detailed YouTube videos that show you exactly what needs to be done.
For a 4-cylinder engine, you're probably only going to have to invest about an hour of your time and replacing all of the spark plugs. To save yourself at $100 that's not too bad of a trade-off. You do want to make sure right off the bat that you've got the right spark plugs for your vehicle before you start anything. Sites like AutoZone can really help you out with this because they can organize their pages by make, model and even year for you if you want.
There are spark plugs that are designed for high performance vehicles and there are glow plugs that are meant to be used in diesel engines, so you really need to make sure that you have the right kind for your car before you get started. As we said, the price can be extremely low so it shouldn't break the bank at all to replace every spark plug in your engine at the same time.
If you go to a site like Amazon, you might be able to get four replacement plugs for a round $20 in total. When you're sure you have the correct spark plugs, you're only going to need a handful of other tools to get the job done.
If you're not comfortable working with tools like a gap gauge or a spark plug wire puller, things that are not commonly used in your average car maintenance, or you don't have them all handy, there is no harm in going to a professional to get the job done. It's also worth noting that if you have a V6 engine then you may need to remove part of the intake manifold to actually get where you need to go. That's a much more in-depth process and if you haven't done any work under the hood of your car before, it may not be the place that you want to start.