Car Repair Tools

How to Use a Spark Plug Socket for Auto Repairs


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One of the most basic of auto repairs, a spark plug socket set is very useful in removing and replacing spark plugs from the engine block in your car. Spark plugs typically will last you 30,000 miles before they need replacing, but this will vary depending on how rich your car is running. Since spark plugs are often set deeply into the block of an engine, the only way to get them out is by using a socket wrench with the right spark plug socket size attached. For foreign cars, you will most likely need a metric spark plug socket set. American-made vehicles use standard SAE measurements in fractions of inches. Follow this instructional and learn how to remove old spark plugs with a socket wrench.

Tools and Materials:

  • Spark plug socket wrench
  • Sockets (metric or SAE)
  • Socket extension
  • Fine grit sandpaper or emery board
  • Replacement spark plugs

Step 1: Open Hood and Locate Spark Plugs

Open the hood of your car and secure it with the rod if need be. Locate the spark plugs. If you are unsure where to find them, look for the distributor cap: a round cap with several thick wires plugged into the top. Trace these wires to the engine block. Each wire leads to an individual spark plug. 

Step 2: Remove Spark Plug Wires

One at a time, remove the spark plug wire from the spark plug which is inserted into the engine block. They may be on rather tight, so pull with some force until the wire is free. Do one spark plug at a time so you don't confuse which wire goes where.

Step 3: Find the Right Socket Size

With the top of the spark plug exposed, pick a socket that looks like it will fit. Holding it in your hand, place it over the top of the spark plug. If it is obviously too small or too big, adjust the size socket as needed. The right socket should fit over the top of the plug snugly, yet not be able to rotate around it loosely. 

Step 4: Attach Socket to Wrench

On the backside of the socket there is a smaller square hole. This is where the driver of the socket wrench goes. Drivers come in different sizes, so pick the wrench that fits. If you need to reach the socket deep to grab the spark plug, attach an extension to the wrench between it and the socket. Make sure the pieces snap together. 

Step 5: Loosen and Remove Plug

Fit the socket around the plug all the way. Set the socket wrench so it turns counterclockwise (to the left) and ratchets to the right. Rotate the plug until you feel it come free from the engine block. Reach in and remove the plug.

Step 6: Clean and/or Replace Plug

A bad plug will have its metal hook-like end covered in blackened soot. You may be able to clean this off with an emery board or fine sandpaper, but if the plug is old enough you will want to replace it. Make sure you have the right size replacement plug. Place it into the hole in the block, set the socket wrench to the tightening setting and secure it in place. The wrench should turn to the right and ratchet to the left. 

Repeat these steps for each of the other plugs, one at a time. If it has been a long time since they were replaced, you're better off replacing them all. 

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