What are the tips for changing spark plugs in a Subaru?
3 Answers
Subaru spark plug replacement tips include: using a quick-release socket and a cross-head screwdriver can make the process easier; remove the engine cover, clean the dust around the high-voltage wire terminals, and when installing new spark plugs, simply tighten them with the socket, being careful to avoid dust ingress. Spark plugs, commonly known as sparkers, function by discharging the high-voltage pulses delivered through the high-voltage wires, creating an electric spark that ignites the air-fuel mixture in the cylinder by breaking down the air between the two electrodes. Taking the Subaru Forester as an example: its dimensions are 4640mm in length, 1815mm in width, and 1730mm in height, with a wheelbase of 2670mm. It is equipped with a 2.0L naturally aspirated engine, delivering a maximum power of 113kW and a maximum torque of 196Nm, paired with a CVT continuously variable transmission.
When it comes to changing spark plugs, I often tinker with my Subaru cars, like the Forester or Impreza with their horizontally opposed engines. The spark plugs are located on the side of the engine, where space is tight and it's easy to burn your hands, so it's best to do it when the engine is cold to avoid burns. First, prepare a dedicated spark plug wrench, around 16mm in size, and a torque wrench to prevent over-tightening. Be gentle when removing the ignition coil wires to avoid breaking the small clips on the wires. After unscrewing the old spark plugs, check the electrode gap—it should normally be between 0.8 to 1.0 mm. Excessive carbon buildup indicates an unhealthy engine, so clean the hole of dust before installing the new spark plugs. Subaru recommends NGK brand spark plugs, which come with a preset gap—it's best not to adjust it. Apply some anti-seize compound to prevent the threads from rusting. When tightening, first hand-tighten the spark plug a few turns, then use the torque wrench set to around 26 N·m (Newton meters) to lock it in place, as the manual specifies slightly different values for different models—mine happens to be exactly 25 N·m. After the replacement, start the engine, and you'll immediately notice smoother performance and quieter operation. Replacing them early can save fuel and prevent ignition issues. If the spark plug gap widens, it can lead to sluggish acceleration, and checking the condition of the old spark plugs can give you an idea of the engine's aging.
As an experienced driver, I believe changing spark plugs requires attention to safety and details. The horizontally opposed engine layout of Subaru makes the spark plug positions a bit awkward, and excessive force may damage the coil. It's recommended to perform the operation after the car is completely cooled down, with tools like a spark plug wrench and gloves prepared to keep hands clean. When removing the coil wires, do it slowly to avoid pulling and damaging the connectors. After removing the old spark plugs, check for wear; if the electrodes are heavily eroded, it indicates a fuel supply issue in the engine. Choose the correct spark plug model, such as NGK ILKAR7L-11, and hand-thread them into the holes initially before slowly tightening them. The torque should be set at 28 Nm to prevent thread damage. Mistakes during the operation may lead to oil leaks or coil short circuits, which can be costly—my neighbor made this mistake and had to pay a hefty repair bill. After installing new spark plugs, the engine responds faster, acceleration becomes smoother, and there's a slight improvement in fuel efficiency. In fact, neglected spark plugs can cause starting difficulties. Incorporating regular maintenance, such as inspecting them every 40,000 kilometers, helps prevent minor issues. Keeping the car in good condition ensures it runs safely and economically for many more years.
