There’s a likely probability you will need to replace your old and worn out spark plugs several times while you own a a 2008 GMC Sierra 3500. 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. Like most engine components, spark plugs experience wear over time and eventually need replacement, but fortunately this is a repair you can do on your own. Odds are, if you’ve found yourself here, you have no idea how to do that, or potentially 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 about 20-45 minutes. This article will go over everything you should need to know about your GMC Sierra 3500’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 2008 GMC Sierra 3500
How often should I change my spark plugs?
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 GMC for the 2008 Sierra 3500. Of course, if you drive your vehicle more aggressively or own a Sierra 3500 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 earlier than the recommended schedule, such as:
- Problems starting your engine
- Rough idle
- Engine misfiring
Note that this list is absolutely 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 GMC Sierra 3500’s spark plugs on a regular basis.
Changing spark plugs on a 2008 GMC Sierra 3500
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.
Helpful Tools
- 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 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 definitely 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 is helpful for countless other jobs.
- 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 torque wrench is a very important tool to have in your garage. You should check your FSM (factory service manual) to determine the correct torque rating to use when putting in the new spark plugs for your 2008 GMC Sierra 3500 to be sure they are installed properly.
Tips for changing spark plugs on your 2008 GMC Sierra 3500
- First, remove the negative terminal of your battery. You should always disconnect the battery anytime you work on the electrical system of your GMC Sierra 3500 or any other vehicle.
- It’s not a bad idea to use 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.
- The most important thing 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. You should wait at least 30 minutes after any kind of operation before attempting to replace the spark plugs on your 2008 GMC Sierra 3500
- 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 small amount of anti-seize to the threads of their spark plugs, especially on older vehicles.