Spark Plugs - How to change and check for signs of other problems

Spark Plugs are a simple and easy easy way to keep you car performing well and you fuel economy high. They typical last 15-30k miles and with most cars costing around $10-20 in parts its a cheap maintenance tactic to keep your car running great.

How to tell if is time to replace, well there's a few thing to look for when your looking at a spark plug. Color, shape of electrode, and fluids on  plug and and contact point. If you don't want to pull the plugs every oil change (which I recommend) you can also get a feeling on when to change your plugs by keeping track of you mpg and your overall cars performance. Weak acceleration, rough idle and poor mpg are all sign of failing plugs.

First thing to look for and the easiest to see is if there are any fluids on the plug. Fluid above the thread mean a possible valve cover leak, below or on the thread signifies a leaking head gasket or possible piston ring failure.

Next is the color. The plug should be a light tan color. Dark or black mean to much fuel, white means not enough. These signify possible fuel issues such as bad distributor cap, rotor or even a fuel filter or pump.

The electrode is the the next thing to check. It should be a larger flat stem, as the plug gets older it will become a finer and finer point until its almost invisible.

Notice the worn electrode, but there is no fluid
on the plug and the color is near perfect

This is the same plug brand new. Here you can
see how much larger the electrode is

Lastly is the contact point. To check this you will need a spark plug gap tool (available at any auto part store for a few cents). Every car has a specific gap for optimal spark firing. if the gap is to small it will make contact to often if to far (which will happen over time as the electrode wears down) it won't make proper spark causing bad MPG and performance

Here's how to access and replace them when and if needed. You'll need a park plug socket (5/8 fits most cars) and about an hour of time. Thats it.

Do one plug at a time checking each for signs as above. This will prevent the spark plug wires from becoming mixed up. They have a specific order they go in and if not put back on in the correct order your car will NOT run.

Simply remove the plug wire insert the spark plug socket and remove the plug. Then replace with new pug if needed making sure to use threat protectant and not over tightening. The reason for the thread protectant is most heads now are aluminum and spark plugs are steel. The two metals will react causing the treads to to wear out. When tightening they only need to be hand tight or else you can strip out the head causing serious damage.