Spark plugs keep a car’s engine firing and the vehicle purring along.
As with all car parts, spark plugs have an average lifespan.
When that runs out, the engine can stall, fuel consumption climb and the vehicle isn’t as quiet or responsive as usual.
Installing new spark plugs is relatively quick and easy.
All you need is the correct tools and good quality replacement parts manufactured for your vehicle.
Here’s the how, what, where and when of DIY spark-plug installation.
How often do spark plugs need replacing?
Spark plugs should be replaced every 20,000 km or two and half years.
However, there are obvious signs that your car’s spark plugs are worn, dirty or defective.
When you fail to recognise these early warning indicators, there’s a heightened risk of engine damage.
Signs that your car needs new spark plugs
When a vehicle is sluggish, misfires frequently or stalls after ignition, there’s a good chance the spark plugs aren’t operating as they should.
Similarly, if the car uses more fuel or the engine makes a rattling, pinging or knocking sound when idling, it may be an indication the engine is not firing properly.
Check the spark plugs’ condition
The only way to identify the problem is to check the condition of the plugs. That means rolling up your sleeves and getting under the hood.
Before you do that, make sure the engine is cool to the touch.
Fortunately, you can assess whether the spark plugs are the culprit by removing just one plug.
A ratchet socket wrench with an extension bar will do the trick.
How to expose a spark plug
First, you have to expose the plug by gently removing the rubber cover containing the wire.
If there’s a dark, sooty residue around the electrodes, evidence of burning or a white build-up at the point of contact between the plug and the engine head, it’s time to replace the spark plugs.
Steps for replacing spark plugs
1. Replace one spark plug at a time. Spark plugs fire in sequence. When you re-attach a wire to the incorrect plug, the engine will run poorly, if at all.
2. Check the gap between the two electrodes using a gap or feeler gauge. If it doesn’t match the dimensions published in the owner’s manual, make the required adjustments.
You can do this by:
- hooking the gauge on the ground electrode and tugging gently to widen the gap, or
- tapping the electrode on a wooden surface to narrow the gap.
3. Ensure the threads on the engine head are clean and dust-free. Use a wire brush to dislodge debris around the wire terminal.
4. Check all the leads. If they’re damaged or cracked, replace them at the same time as the corresponding spark plugs.
5. Lightly spray Q20 onto the spark plug’s thread, insert it into the head and tighten by hand.
6. Use the ratchet socket wrench to tighten the plug, but don’t overdo it.
7. Re-attach the wire and plug cover.
8. Repeat the process with the remaining spark plugs.
Where to get top quality spark plugs in South Africa
Masterparts stocks a comprehensive selection of automotive spares and parts for virtually all vehicle makes and models.