Ignite your knowledge about Spark Plugs!

When it comes to small engine repair, spark plugs can tell you a lot! Something so cheap and yet so essential to a properly running motor. You would never imagine how much a spark plug can tell you about the condition of a running engine. I want to share with you a brief guide to understanding spark plugs. There are more than half a dozen different conditions a spark plug can create. The most common are the following three.

Normal                   Carbon Fouled                  Oil Fouled

(These pictures are the courtesy of Denso Iridium Power)

The first picture is a normal spark plug. Its center electrode is nice and tan. This means the plug is burning the gas properly and the engine rings are in good shape since there is no oil present.

The middle picture has a dry black deposit over the entire bottom. This is due to a rich air-to-fuel mixture which means there is more gas than air going into the engine. The most common causes are a dirty air filter or an improperly adjusted carburetor. If the wrong spark plug is being used, this can also contribute to more black deposit accumulation.

The third picture is oil fouled. Notice it is also black, but it much more oily. As an engine wears out the piston rings lose their seal. When this seal is broken the oil in the crankcase seeps around the piston rings and coats the bottom of the spark plug. This oil is not able to be burned off. Instead it will stop the spark plug from sparking. To fix this will require an engine rebuild.

A picture of how water mixes with gas

This is just a quick picture of how water mixes with the gas. I pulled this out of a Briggs and Stratton gas tank. The layer on top is gas, which can be seen as a yellow color. The bottom layer is water, and is a foggy white color.
Water can get into gas either through the gas cap, or the air filter when equipment goes uncovered in bad weather, or when being washed. So take caution when washing or storing your equipment outside.

How a dirty air filter effects your engine.

Many times we hear about things that must be done to properly maintain our lawn equipment. Change the oil every 25hrs! Check the filter! Winterize your equipment before storing! But do you know why? My goal is not only to fix equipment, but share why this is important, and what effect it has on the engine. Here are 2 reasons why its important to change your air filter at the recommended intervals.

Reason #1 – A dirty air filter will cause a good engine to run bad!

A dirty air filter, such as the one in the picture, will cause the engine to run as if the choke was always on. This choke affect will cause the engine to run rough and puff out blue smoke. Blue smoke means that raw gas is going unburned, and because of this, is passing through the muffler and into the air.

Reason #2- A dirty air filter raises the chances of fouling your spark plugs!

The second reason its important not to run dirty filter is because it can lead to spark plug failure. When an engine is run with a dirty air filter, the extra gas that is drawn into the engine (due to the choke affect) will accumulate on the bottom of the spark plug. This build-up is a black powdery deposit. If it becomes to thick, it can lead to spark plug failure.

It conclusion, regular maintenance keeps money in your pocket. It is that simple!

PS. Don’t wait until your filters look like this to bring them in for a tune-up!!!!

(Air Filter is off of a 5.5hp Intek Briggs and Stratton rototiller)

If you do not feel comfortable doing any of the things listed above, just know that Metal In Motion is there to help. So stop by Lenoir City, and give us a visit! To find us just click here