It is imperative that you ensure your spark plugs are in good condition. There’s a likely chance you will need to replace your worn out spark plugs several times over the course of owning a 1999 Cadillac Seville. Spark plugs are one of the most vital components inside your engine as they trigger the entire combustion process that starts and keeps your engine running for many thousands of miles. Like most engine parts and components, spark plugs experience wear over time and eventually need replacement, but fortunately this is a repair you can do on your own. Chances are, if you’ve found yourself here, you have no idea how to do that, or maybe 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 Cadillac Seville’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 1999 Cadillac Seville
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 Cadillac for the 1999 Seville. Of course, if you drive your vehicle more aggressively or own a Seville 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 telltale signs of a car that may potentially need a spark plug replacement prematurely, such as:
- Engine misfiring
- Rough idle
- Problems starting your engine
Note that this list is of course not comprehensive, and these problems on their own do not necessarily point to the spark plugs being the solitary culprit. However, the best way to prevent any issues with your vehicle is to take care of it with regular maintenance, and you are definitely doing so with the responsible decision to replace your Cadillac Seville’s spark plugs on a regular basis.
Changing spark plugs on a 1999 Cadillac Seville
This is a process you can 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.
Helpful Tools
- A spark plug gap tool. This allows you to check the gap of your spark plugs and increase or decrease 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 easier to check the exact gap, and it comes in handy for a decent number of other jobs.
- A set of spark plug sockets – These come in very handy because many standard sockets are not deep enough for spark plugs. Additionally, 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 a ton 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 an issue. This tool can help you diagnose the exact problem.
- A torque wrench is a essential 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 1999 Cadillac Seville to be sure they are installed properly.
Tips for changing spark plugs on your 1999 Cadillac Seville
- 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.
- Before you begin, remove the negative terminal of your battery. You should always disconnect the battery anytime you work on the electrical system of your Cadillac Seville or any other vehicle.
- During this process, one of the most vital things to ensure you do 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.
- Your engine should be completely COLD before you replace your spark plugs. Ensure you wait at least 30 minutes after any kind of operation before attempting to replace the spark plugs on your 1999 Cadillac Seville
- It’s not a bad idea to use dielectric grease when installing new spark plugs. You can apply a a very light coating 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.