It is imperative that you ensure your spark plugs are in good condition. There’s a likely chance you will need to replace your old spark plugs several times while you own a a 2004 Ford Mustang. Spark plugs are one of the most vital parts inside your engine as they trigger the entire combustion process that starts and keeps your engine running for many thousands of miles. Similar to most engine parts and components, spark plugs experience wear over time and eventually need to be replaced, but fortunately this is a repair you can do yourself. Odds are, if you’ve found yourself here, you have no idea how to do that, or perhaps you’d just like to know what kind of spark plugs you need to buy. The complete process of changing your spark plugs should take roughly 20-45 minutes. This article will go over everything you will need to know about your Ford Mustang’s spark plugs, whether you need some general information or a full, step-by-step guide to performing a spark plug change.
Correct spark plugs on a 2004 Ford Mustang
How often should I change my spark plugs?
Very generally, it is advised that you replace spark plugs once every 20,000 to 40,000 miles. Of course, please make sure to check your owner’s manual to determine the exact interval determined by Ford for the 2004 Mustang. Of course, if you drive your vehicle more aggressively or own a Mustang with some modifications, you may want to consider changing your spark plugs closer to the 20,000 miles end of that spectrum.
However, there are also classic signs of a car that may need a spark plug replacement earlier than the recommended schedule, such as:
- Engine misfiring
- Rough idle
- Problems starting your engine
As a quick note, keep in mind that this list is absolutely not comprehensive, and these problems on their own do not necessarily point to the spark plugs being the standalone culprit. However, the best way to prevent any issues with your vehicle is to take care of it with organized maintenance, and you are definitely doing so with the responsible decision to replace your Ford Mustang’s spark plugs on a regular basis.
Changing spark plugs on a 2004 Ford Mustang
This is a process you should be able to do on your own with some commonplace garage tools. Of course, consult your owner’s manual, as well as a factory service manual or an equivalent Haynes or Chiltons manual. The video shown below does a good job of outlining the process.
Helpful Tools
- A set of spark plug sockets – These come in extremely handy because many standard sockets are not deep enough for spark plugs. Also, some spark plug holes are a bit smaller, so it requires a thinner wall like the one featured in the product here to fit. The linked product also features a magnet to keep a good hold of the spark plug so you do not drop it into your engine bay!
- A spark plug tester – this is definitely a niche tool, but it can save you lots of time. Although we’ve discussed spark plug replacement being a good thing to replace regularly and not just when issues occur, you may also be replacing your spark plugs because of something going wrong. This tool can help you diagnose the exact problem.
- A spark plug gap tool. This allows you to check the gap of your spark plugs and change it if necessary. Most plugs will come pregapped, but if this is not the case, you should for sure have one of these.
- I also highly recommend you have a feeler gauge as it makes it a bit more straightforward to check the exact gap, and it comes in handy for a decent number of other jobs.
- A torque wrench is a very important tool to have in your arsenal. You will want to check your factory service manual to determine the correct torque rating to use when installing the new spark plugs for your 2004 Ford Mustang to be confident they are installed properly.
Tips for changing spark plugs on your 2004 Ford Mustang
- It isn’t a bad idea to use dielectric grease when installing new spark plugs. You can apply a a tiny amount to the inside of the boot and the ceramic part of your spark plugs. It prevents voltage leak and helps avoid the misfortune of the boot fusing to the spark plug over time.
- One of the most important things to remember is to avoid overtightening the plugs or worse, cracking them due to overtightenting. Use a torque wrench capable of lower, more precise torque ratings to be sure that you don’t make this mistake.
- Before you begin, disconnect the negative terminal of your battery. You should always disconnect the battery anytime you work on the electrical system of your Ford Mustang or any other vehicle.
- You should replace spark plugs on a cold engine. Wait at least 30 minutes after any kind of operation before attempting to replace the spark plugs on your 2004 Ford Mustang
- Take this (unofficial advice) lightly as many spark plug manufacturers advise against the use of anti-seize. However, I have heard from numerous old-school mechanics that they always apply a light coating of anti-seize to the threads of their spark plugs, especially on older vehicles.