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Tools To Change Spark Plugs

Spark plug tools

One of the easiest home DIY projects in most vehicles is to change out the spark plugs. Plugs provide the spark that ignites the fuel in gasoline, natural gas and some diesel engines. Carbon buildup and spark head degradation eventually lead to their needing replacement.

The interval between replacements will depend on the vehicle make and model as well as the plug type. For most vehicles, this falls into the 1-2 year range, depending on use and fuel type. Many mechanics recommend that the spark plugs be removed and cleaned annually as a part of a tune up, even if the plugs themselves don't require replacement. The cleaning removes carbon buildup on the head of the spark plug, making it more efficient.

In nearly all vehicles, spark plug replacement is relatively cheap to do. The average 6-cylinder car will require 6 spark plugs and they will cost roughly $3 each. Some newer cars have very specific plug requirement and those will often cost much more and some vehicles have double the plugs, so a 6-cylinder car may actually need 12 plugs.

For the mechanic, this is a quick 1/2 an hour or less job to remove and replace each plug in the engine. Shop charges are usually less than $100 for the work. For the DIY home mechanic, it can take up to an hour to get the job done, depending on the type of vehicle.

Some newer vehicles require many components be removed from the engine just to get to the plugs - this adds to the cost.

On most jobs, the following tools will be required to remove and replace spark plugs from most gasoline engines:

  1. Socket wrench in 3/8" drive
  2. Spark plug socket in the appropriate size (usually 5/8" and 13/16" deep socket, often with a rubber insert)
  3. Socket wrench extension appropriate to the job (for most, it will likely be a 3-inch extension)
  4. Gap gauge

The socket wrench is obviously to unscrew and screw in the spark plugs. The extension is to make it possible to get to the plugs and the socket is to fit around the plug and easily remove it. The rubber inside the socket allows it to grip the porcelain neck of the socket for easy removal. It's often recommended that another socket of the same size, but without the rubber, be used for inserting new plugs so that the socket can be easily extracted. Otherwise, needle nose pliers or the like may be needed to get the socket off of the plug once inserted.

The gap gauge is optional, but can be useful for the two or three dollars it takes to get one. These measure the gap between the spark plug tip and the armature in between which the spark is created. If the gap is too large or too small, the engine will not run at peak performance.