Inside every engine, thousands of mini-explosions happen every minute, all thanks to a spark plug. Over time, these little guys wear out, leading to a drop in power, worse fuel economy, and even potential engine damage down the line. This guide dives into how to swap out spark plugs, check their condition, and clean them up to squeeze every bit of life out of them. For a refresher on the basics, check out guides on what spark plugs are and how to decode spark plug part numbers.
How Often to Change Spark Plugs
Typically, spark plugs should be swapped out based on what the owner’s manual suggests. But there are some signs that scream for an early change:
- Rough running: Worn-out spark plugs can cause misfires, leading to rough idling, hard starts, and engine hiccups.
- Loss of power: If a spark plug misfires, fuel might not burn properly, resulting in sluggish acceleration.
- Poor fuel economy: When spark plugs fail to ignite the air/fuel mixture correctly, unburned fuel just gets wasted out the exhaust.
Location of Spark Plugs in Different Engine Types
Most spark plugs sit right on top of the rocker cover or close by on the engine head. Here’s where to find them based on engine type:
- Four-cylinder: Usually right on top of the engine or just below on the side of the head.
- Straight 6: Same deal—right on top or just below on the side of the head.
- V6: Three plugs on each side of the engine, either on top of the rocker cover or just below.
- V6 Front Wheel Drive: Three at the front and three at the back, often hiding under the intake manifold. Access can be tricky.
- V8: Four on each side of the engine, sitting on top of the V. Older V8s might have them on the side of the head near the exhaust or intake manifolds.
How to Check Spark Plugs
To check spark plugs, follow these steps: Remove each plug and inspect for cracks. Give them a twist and wiggle to make sure they’re not loose. Look closely at the electrodes for any wear or heavy deposits. If any damage is spotted, it’s time for a replacement. If they look good, clean them up with a wire brush, then use a spark plug gap tool to check the gap against the specs in the workshop manual. If adjustments are needed, gently pry the gap open or press the electrode on a firm surface to close it up.
