Spark plug electrodes erode over time due to sparking and corrosion. The result is the widening of the gap and a subsequent loss of efficiency.

Replacing worn out spark plugs with new ones reduces misfires and emissions, and restores power and efficiency.

For maximum fuel economy and peak engine performance, your spark plugs should be replaced every 12 months or 10,000 klm. This may vary depending on the type and model of your vehicle.

When installing new spark plugs, all of them need to be changed. Mixing plugs of various ages will cause the engine to run inefficiently.

Refer to your Owner’s Handbook for further instructions.

Tools and Equipment to replace the Spark Plugs

• Set of Spark Plugs
• Spark Plug Wrench or Spark Plug Socket and Ratchet.
• Spark Plug GapGauge.
• Torque Wrench (optional).
• Rag or Brush.
• Length of 5/16" Rubber Hose approximately 6" long.

Before replacing the Spark Plugs

Proper maintenance and service procedures are vital to the safe, efficient operation of all motor vehicles, as well as to the safety of the person performing the work. Whenever you're working on your vehicle follow these important safety rules:

• Don't work under a car unless it's securely supported.
• Don't run the engine without proper ventilation.
• Be careful when working around hot objects.
• Have a first aid kit handy.
• Don't smoke around the engine.

Before You Begin

• Purchase new plugs that are the right size and heat range for your specific engine (consult a spark plug manufacturer's guide). Never rely on cross-references.
• Allow the engine to cool completely before attempting to remove the old plugs. This is particularly true if the engine has aluminum cylinder heads.
• Gather together all the tools and equipment you'll need before you start.
• Adjust the new plugs to the proper gap beforehand. The correct gap for your vehicle's engine can be found in the owner's manual.

Before you can reach the plugs you will first have to remove the wire that leads to the distributor. To avoid mixing up the spark plug wires, it's a good idea to remove and replace one plug at a time or use tape to label each wire so you know which one fits to which plug. Once you have removed the wires clean off the grit around them.

Checking the Cylinder Head Threads

Visually inspect the cylinder head threads. They should be in good condition, clean, and free of dirt and debris. This new spark plug should freely screw into the cylinder head by hand. Any binding of the plug is an indication that there's a problem. Remove the plug and inspect the threads.

Installing the new Spark Plug

• Make sure that the area around the spark plug port is clean. Wipe the seat with a clean rag to ensure proper contact between the new plug and the seat.
• Use a spark plug socket to suit the hexagonal part of the spark plug to ensure that no burring occurs
• When removing the spark plug, ensure that no fouling, such as oil on the outside of the plug, enters inside the engine.
• When installing spark plugs, clean the seat for the spark plug in the engine, check the gasket, and then mount the plugs on their seats.
• Insert the plug into the spark plug hole by hand and turn it clockwise until it's snug. If the spark plug hole is hard to reach, try attaching a short piece of 5/16" rubber hose to the top of the plug and use it as an extension to help reach the hole.
• After installing the plug be hand as far as it will go, firmly tighten it with a spark plug wrench or socket, rotate between ¼ and ½ of a turn for flat seat plugs (or between 1/5 and1/4 of a turn when they are to be re-used). For taper seat plugs use a 1/16 turn.
• Tightening too much may cause distortion of the plug housing, and in extreme cases could cause engine damage. Therefore, proper installation of the spark plug is important for life and performance of the spark plug.
• It's a good idea to use a torque wrench, if one is available, to ensure that the plug's properly seated. Do not overtighten. Remember, you'll get an accurate torque reading only if the spark plug and cylinder head threads are clean and dry.
• Reattach the plug wire to the new plug. Use a twisting motion on the boot until it's firmly seated on the top of the plug.
• Repeat the above steps for each plug you're replacing.

Torque

Torque is one of the most important factors of spark plug installation. If under torqued, heat-transfer will be incomplete causing high temperatures. Over torquing can cause damage to the plug and to the engine.

*1N· m=0.1020kgf· m

Note: The installation torque values shown above apply to new spark plugs without lubricating the threads. If threads are lubricated, the torque value should be reduced by approx. 1/3 to avoid overtightening.

Tips

• Follow these instructions carefully. Read and be sure you understand them before you begin.
• Gather together all of your tools and supplies before you begin.
• Allow plenty of time to do the job so you don't have to hurry.
• Remember that these are general instructions. For more detailed instructions pertaining to your specific vehicle, consult an appropriate repair manual.
• Safety is important whenever you're working around machinery. Beware of hot objects, sharp instruments and hazardous materials.
• Don't substitute tools unless you're sure you won't compromise either your safety or the performance of your vehicle.