Changing and cleaning spark plugs
Before you start.
Changing and cleaning spark plugs
Before you start.
Spark plugs
Changing or cleaning your spark plugs is a good way of maintaining your car. Dirty or worn spark plugs can result in fuel not burning cleanly, or even fuel in one or more cylinders not igniting. This can make your engine run roughly and vibrate a lot. Changing spark plugs on most cars is pretty easy, particularly so on older ones. In addition, you can clean spark plugs periodically to remove carbon build up. This will make them last a lot longer.
Step 1.
Open the car bonnet / hood and locate the spark plug leads. In the picture above they are the yellow and red leads. On newer cars they may be a bit harder to locate. Consult the car's manual if needed.
Step 2.
Remove one of the leads from a spark plug. Only remove one at a time so you do not mix them up. If you do mix them up, your cylinders may spark at the wrong time, which is very bad news for the engine.
Using a socket wrench, socket extension bar and the right size socket for your spark plugs, gently loosen the spark plug. Typically they turn anti-clockwise to loosen, and clockwise to tighten when viewed from above. The best way to loosen them is to seat the socket wrench firmly on the spark plug, then gently apply force to the handle end of the socket wrench. The force generally does not need to be too much, as you will have good torque due to the handle of the socket wrench being so far from the central turning point.
Step 4.
Once the spark plug is freely turning, you can usually remove the socket wrench and loosen it by hand. Keep a firm grip on it as you unscrew it to prevent it from dropping down into the engine bay. When unscrewed you can remove it.
A comparison of a new spark plug and an old one.
Step 5.
Once the old spark plug has been removed, place the new spark plug in the spark plug hole and screw it in by hand. It may take a bit of practice to get it in the hole right.
Once the new spark plug is screwed in hand tight, use the socket set to tighten it. It does not need to be in super tight. Just gently screw it in until the socket wrench stops turning then give it one last shove on the end of the socket wrench.
Step 6.
Once the new spark plug is in place, remove the socket wrench and reattach the lead. Clip the end of the lead and firmly press it down on to the spark plug. Wriggle it from side to side and push down until it is firmly on.
Step 7.
Repeat the above steps for each spark plug. Remember to only unplug one lead at a time.
Cleaning spark plugs
Spark plugs can some times be reused if they don't have too much wear or carbon build up.
After removing the old spark plug you can inspect it to see how clean it is. Generally there will be some carbon build up. If there is not too much, you can clean the spark plug up and re-use it.
Using sand paper or glass paper, rub the build ups of carbon away from the spark plug. In particular, clean the bit between the small gap where the spark occurs. The best way to do that is to use a small piece of sand paper, fold it over some times and fit it in the gap, cleaning as you go. This tends to be hard on the sand paper, so you may need to re-fold it several times to get the gap cleaned.
Clean around the small circular protrusion too.
Basically you want to make the ends of the spark plug as clean as you can get them. See the comparison below.
Once the spark plugs are as clean as you can get them with sand paper, dip the ends in a small amount of petrol to clean them up some more. As can be seen from the image below I stood mine in a simple can for a while. I rinsed the can out with water first, then with petrol. Notice the grime coming off of them.
Finally clean the heads off with a tissue to remove excess dirt and petrol. I am not sure how many times you can do this, or how effective it is. It would not be something I would want to do too often seeing as how brand new spark plugs cost me just $25 for my car.
