Content

• To step
• Part 1 of 2: Removing the old spark plugs
• Tips
• Warnings
• Necessities

Gasoline and LPG combustion engines operate by controlled explosions of energy, partly controlled by spark plugs. The spark plugs use the electrical current from the ignition to ignite the fuel. Spark plugs are an essential part of a properly functioning combustion engine. Spark plugs are also subject to wear, but fortunately it is not difficult to diagnose problems and possibly replace the spark plugs if you have the right tools and knowledge. Skip to step 1 for more information.

To step

Part 1 of 2: Removing the old spark plugs

1. Locate the spark plugs (refer to the owner's manual). When you open the hood you will see a bundle with 4 to 8 cables that lead to different points in the engine compartment. The spark plugs are located under the caps at the ends of these cables on the side of the engine block.
   • With a 4-cylinder engine and a 6-cylinder in-line engine, the spark plugs are in a row at the top or side of the engine block.
   • With V6 and V8 engines, the spark plugs are distributed on the two sides of the block.
   • On some cars you must first remove a cover from the block to find the spark plug wires, follow these wires to find the spark plugs.Always read the owner's manual to find out where the spark plugs are, how many are there and what size wrench you need to remove them. It is also a good idea to number the cables on the cylinder so that you will soon know which cable belongs where after you have replaced the spark plugs. Immediately check the cables for possible damage and cracks, in which case cables must also be replaced.
2. Allow the engine to cool before removing spark plugs. After the engine has been running for a while, the spark plugs, engine block and exhaust system become extremely hot. Do not remove the spark plugs until the engine has cooled down so that you can touch the block without any problems. Collect the necessary tools while you wait. To replace spark plugs you need the following things:
   • Socket set with ratchet
   • An extension
   • Spark plug wrench, which is usually included with a socket set
   • A feeler gauge, available at auto parts stores
3. Measure the distance between the electrodes on the spark plug. This number will be somewhere between 0.5 and 0.7 mm, depending on the spark plugs and the type of car. Read your owner's manual to find out the optimal distance for the spark plugs for your type of car and use a feeler gauge to check the distance.
   • If the distance between the electrodes is too great, but the spark plug is still in good condition and adjustable, you can try to shorten the distance by tapping the spark plug on a wooden surface with the feeler gauge in between for the correct distance. Or you can buy new spark plugs. Usually it is recommended to replace the spark plugs every 20,000 km, but check your owner's manual for the correct interval. Spark plug replacement is normally done during a major service. Spark plugs are not very expensive, so it may be a good idea to replace them more often than prescribed.
   • If you plan to replace your spark plugs yourself from now on, invest in good tools, such as a feeler gauge. This is a metal ring that you can use to measure the distance between the electrodes. The following also applies to parts: only buy parts of good quality, that always pays off.
4. Buy the right spark plugs. You can find which spark plugs you need in the owner's manual or you can look it up in a reference book at an auto parts store. Search for the make, type and year of your car. There are hundreds of different types of spark plugs, ranging in price from 2 euros to 15 euros, made of platinum, yttrium, iridium, etc. Spark plugs made of precious metals are more expensive, but more resistant to wear. If you are unsure, check at an auto parts store or go to a branded garage and inquire at the warehouse.
   • Usually, it is a good idea to buy the same spark plugs as your old spark plugs. Never buy lower quality spark plugs, and vice versa: you don't have to buy more expensive spark plugs if your current spark plugs are good enough. The manufacturer has not installed that type of spark plug for nothing, you can use the same with confidence.
   • You can buy spark plugs with a fixed distance or adjustable spark plugs, you can decide for yourself whether you want to regularly check and adjust your spark plugs remotely. If you want to do that you have to buy adjustable spark plugs. In any case, check that the distance is the correct distance for your type of car. If you check it yourself, you can be sure. Remove them from the packaging and check the distance.
5. Consider lubricating the spark plugs before installing them. You can apply a very small amount of copper grease to the threads of the spark plugs before installation, if you are installing them in an aluminum engine block. The copper grease prevents a reaction between different metals. You can also put a small amount of silicone grease on the inside of the spark plug cap to make it easier to remove the spark plugs in the future.

Tips

• Spark plugs are often difficult to reach on new cars. Consider replacing the hidden spark plugs first and then the easily accessible ones.
• Use a torque wrench to make sure the spark plug is tightened to the correct torque. Set the key according to your car's specifications. If necessary, call the supplier of the car to find out the prescribed time.
• Use a spark plug wrench with an internal coating or a magnet, then you can be sure that the spark plug will not fall out of the key when you remove or install it (if the spark plug falls, the distance must be measured again and adjusted if necessary).
• Diesel engines do not have spark plugs.
• Be careful that nothing falls into the spark plug hole on the cylinder head. Use an air compressor to remove debris before removing the spark plug. If dirt does fall into the hole, start the car without that spark plug so the piston can push air and dirt out (but keep enough distance to avoid eye damage).
• Normally, the distance does not need to be adjusted with a new spark plug, but it does not hurt to measure the distance.
• Always pull only on the hood and never on the cable itself, as this will damage the cable.
• Buy a maintenance manual for your type of car.
• If the engine is running when a spark plug is not sparking, the spark plug will fill up with fuel. An engine can take up to a minute to burn off the accumulated fuel before the engine returns to smooth running.
• Double check that you have the correct spark plugs. Spark plug type numbers can be very similar and installing the wrong spark plugs can cause a lot of problems.

Warnings

• Allow the engine to cool thoroughly before replacing your spark plugs. The spark plugs and engine block can be very hot and cause burns.
• Keep children away and wear protection for your eyes.

Necessities

• New spark plugs
• Socket wrench with extension arm or spark plug wrench
• Feeler gauge (optional)
• Copper grease
• Silicone grease
• Protective clothing: overalls, gloves and safety goggles