CAUTION: Keep hands, clothing, and tools away from the radiator fan. On some vehicles, the fans may turn on automatically up to 15 minutes after the engine is turned off.
1. Number the wires so as not to mix them up when putting them in place. In most Honda engines, the wires are only long enough to reach the spark plugs; be sure to label them to avoid mistakes.
2. Remove the wire from the tip of the spark plug by grasping the rubber block on the wire. If the block sits very firmly, then you must simultaneously turn and pull on it. Do not pull on the wire directly as this may damage the inner strands of the wire. Engines with two camshafts (DOHC) have candles deeply recessed between the shafts. The wires are arranged in long, solid tubes, which are led through tunnels to the candles; be extremely careful when disconnecting wires and tubes.
3. Use a spark plug wrench to loosen all spark plugs approximately two turns. Depending on the location of the spark plug, a short wrench extension may be useful. Care must be taken to ensure that the axis of the key exactly matches the axis of the candle; if the key is skewed in any direction, the candle may break.
The cylinder head is cast from aluminum alloy. Therefore, remove the spark plugs, if possible, with a cold engine to avoid damaging the threads. If the plugs are difficult to unscrew, apply a few drops of penetrating oil to lubricate the threads or apply silicone grease near the base of the plug, giving them a little time to penetrate.
4. If compressed air is available, use it to clean the area around the spark plug seats. If not, use rags and a brush for these purposes. Be very careful not to let foreign materials get into the spark plug sockets.
5. Remove the spark plugs by unscrewing them from the engine. If the candles are within reach, they can be removed by hand. On DOHC engines, the spark plugs must be unscrewed and removed using a spark plug wrench.