by Pat Goss
Although everybody seems to ignore them, gasoline engines still have spark plugs. And spark plugs are the first thing that you look at if you have any kind of a performance problem at all, whether it’s rough idle, poor gas mileage, hard starting, stalling, anything like that. You start by checking the spark plugs.
Now, when it comes time to check the plugs, the first thing you have to do is take the spark plug wires off of the plugs. Well, a lot of people make a mistake here. They grab a hold of the plug wire and they yank it off of there, and it tears the spark plug boot. So instead of just yanking it off, what you do is you turn the plug wire on the spark plug to loosen the boot and then pull it off. That way you don’t damage the plug wires, and plug wires can be expensive.
Next you’re going to have to take the plugs out of the engine, but before you do that, you take an air hose and you blow air around the plug. Now that’s going to blow any dirt that has collected down there around the plug, it’s going to blow it away. It’s going to keep it from going into the engine when you take the plug out. That’s an important step. Of course you’ll need a spark plug socket. Now a spark plug socket has something in it that holds the plug so it won’t fall out. The plug falls out, hits the ground, and the insulator is cracked.
You’ve taken the spark plugs out. What do you do with them? Well, you take a box or a piece of cardboard and you poke some holes in it and you align them the way they come out of the engine. Now why are you going to do this? Well, there’s more to spark plugs than just whether they’re worn or not. From your parts store, or in many cases off of the Internet, you can get a chart such as this. And by looking at that chart, you can determine if there are other problems inside your engine other than just the spark plugs themselves.
Now before you put the spark plugs back in, well, the gap always has to be checked, and when you’re checking the gap on a spark plug, make sure that you check it with a round wire gauge. You don’t use a flat disk or anything like that. This is the only true way to get an accurate gap on the plug.
Finally, when you’re putting the plugs back in, well you may find that they’re difficult to get started. So you don’t use a wrench. What you do is you use a piece of hose. You put the hose on the body of the spark plug. And it’s flexible. You can guide it into the spark plug hole. You can turn it. It will get the plug started without cross threading it. And once the plug is started, it has to be turned in by hand at least two full turns before you put your wrench on it. And finally, well, don’t over-tighten them. A lot of people tend to over-tighten spark plugs, and that’s a bad thing.
If you have a question or comment, write to me. The address is MotorWeek, Owings Mills, MD, 21117.