One of the most important aspects of vehicle maintenance is ensuring your spark plugs are in good working order. There’s a decent chance you will be required to replace your old and worn out spark plugs several times during your ownership of a 1998 Ford F-800. Spark plugs are one of the most vital parts inside your engine as they begin the entire combustion process that starts and keeps your engine running for many thousands of miles. Like most engine components, spark plugs experience wear over time and eventually need replacement, but fortunately this is a repair you can do yourself. Chances 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 entire process of changing your spark plugs should take approximately 20-45 minutes. This article will go over everything you’ll need to know about your Ford F-800’s spark plugs, whether you need some baseline information or a full, step-by-step guide to performing a spark plug change.
Correct spark plugs on a 1998 Ford F-800
For any 1998 Ford F-800, you can use MOTORCRAFT SP503 spark plugs. These will be an exact fit and will match the required specifications of your engine. As this 1998 Ford F-800 features an 8 cylinder engine, ensure you purchase 8 spark plugs. We always try to recommend the best possible spark plugs for the money, and these spark plugs are either a factory recomendation or an equivalent replacement available now at a reasonable price.
How often should I change my spark plugs?
As a general recommendation, 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 specific interval determined by Ford for the 1998 F-800. Of course, if you drive your vehicle more aggressively or own a F-800 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 needs 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 certainly not comprehensive, and these problems on their own do not definitively 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 routine maintenance, and you are definitely doing so with the responsible decision to replace your Ford F-800’s spark plugs on a regular basis.
Changing spark plugs on a 1998 Ford F-800
This is a process you should be able to do on your own with some ordinary garage tools. Of course, consult your owner’s manual, as well as a factory service manual (FSM) or an equivalent Haynes or Chiltons manual. The video shown below does a good job of outlining the process.
As noted before, you should be able to accomplish a spark plug change with some ordinary tools you likely already have. However, there are a few tools that are specific to this job that you may not have, and we also want to recommend some commonplace tools that you should absolutely have in your toolbox if you do not already.
- A torque wrench is a vital tool to have in your toolbox. You will want to check your FSM (factory service manual) to determine the correct torque rating to use when installing the new spark plugs for your 1998 Ford F-800 to be sure they are installed properly.
- 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 a problem. This tool can help you diagnose the definite problem.
- A set of spark plug sockets – These come in extremely handy because many standard sockets are not deep enough for spark plugs. In addition, 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 gap tool. This allows you to check the gap of your spark plugs and modify it if necessary. Most plugs will come pregapped, but if not, you should absolutely have one of these.
- I also highly recommend you have a feeler gauge as it makes it a bit easier to check the exact gap, and it is helpful for countless other jobs.
Tips for changing spark plugs on your 1998 Ford F-800
Please make sure you reference the video above before you attempt to repair the spark plugs on your 1998 Ford F-800, as well as review your FSM (factory service manual) or owner’s manual. Also, see the tips included below here to help you as you complete this repair.
- 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.
- You should replace spark plugs on a cold engine. You should wait at least 30 minutes after any kind of operation before attempting to replace the spark plugs on your 1998 Ford F-800
- Before beginning, disconnect the negative terminal of your battery. It is wise to disconnect the battery anytime you work on the electrical system of your Ford F-800 or any other vehicle.
- You might consider using dielectric grease when installing new spark plugs. You can apply a a small dab to the inside of the boot and the ceramic part of your spark plugs. It lessens the chance of voltage leak and helps avoid the misfortune of the boot fusing to the spark plug over time.
- Note that this is not official advice 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 tiny amount of anti-seize to the threads of their spark plugs, especially on older vehicles.