Replace Spark Plugs

sparkplugremoval2Replacing spark plugs can be an easy chore—or not—depending on how kind the automotive engineers are. Actually, the location and ease of access to spark plugs depends on many engineering factors including how sleek you want your car to look. Sleek means low and the space has to come from somewhere. The size of the engine compartment is reduced.

Car Words

spark plug is a metal-and-ceramic component that uses electricity to ignite the fuel/air mixture in each cylinder of the engine. A six-cylinder engine has six spark plugs.

Platinum plugs are high quality spark plugs with platinum tips that last longer than conventional plug tips. Why doesn’t every car require platinum plugs? They are expensive. Why do some cars require them? Because the spark plugs are located where they are difficult to replace it makes good sense to replace them less frequently.

So the first trick to replacing spark plugs may be finding the darn things. Fortunately, there are tell-tale signs. Each cylinder in your car’s engine will have a spark plug, and each spark plug requires a wire leading to it. So start by identifying a group of four, six, or eight wires (depending on the number of cylinders) in the engine compartment. Then follow each wire to a spark plug mounted into the engine. Here’s the procedure for replacing spark plugs:

Fix-It Tip

Let your car’s engine cool before attempting to remove plugs. It’s safer (less chance of getting burned), and it will make removing spark plugs easier. If you’re having trouble removing a plug, carefully spray penetrating oil around the base of the plug and let it soak in. Use caution because penetrating oil is flammable and may ignite with heat; it can also damage nearby electronic parts.

1. Use masking tape to mark the wires before removing them from the plugs (so you can put them back on in the correct order). Use any marking system that you know you’ll be able to figure out later.

2. Carefully twist and pull the spark plug wire where it connects to the plug (called the boot) until the boot comes off the plug tip. Make sure you pull on the boot and not the wire or the two may separate.

3. Use a shop rag and small paint brush to clean around the spark plug so debris doesn’t fall into the engine when the plug is removed.

4. Use a spark plug wrench to remove the first plug from the engine.

5. Using a wire feeler gauge, check and adjust the new spark plug gap according to the manufacturer’s recommendation for that engine. The owner’s manual or your parts supplier should have that info. (Note: Always replace a spark plug with the same make and model unless advised to otherwise by a competent auto parts clerk or mechanic.)

Fix-It Tip

Lubricate the threads of the spark plug with Never-Seez or a similar lubricant (available from your parts supplier) to make the plugs easier to remove the next time.

6. By hand, screw the new plug into the spark plug hole until the plug comes in contact with the engine. Then use the socket wrench to tighten the plug two-thirds of a turn. (If you have a torque wrench, it’s preferred to tighten the plug to the torque value recommended by the car’s manufacturer. However, the procedure described here is adequate.)

7. Inspect the spark plug wire and boot for damage, replacing as a unit if needed. Otherwise, place the boot on top of the plug and press firmly.

8. Repeat this process to replace the other spark plugs.

Fix-It Tip

Platinum plugs are high-quality spark plugs with platinum tips that last longer than conventional plug tips. Why doesn’t every car require platinum plugs? They are about twice as expensive as regular spark plugs. Why do some cars require them? Because the spark plugs are located where they are difficult to replace, it makes good sense to replace them less frequently. The difference in cost is typically less than $2 per spark plug. If you really don’t like changing spark plugs, go platinum and do it less frequently.

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