What is the torque for spark plugs?
2 Answers
Generally, the tightening torque for spark plugs is 20N·m. Spark plugs of different sizes require different torque values. For example, a 12mm spark plug typically requires a torque of 20-25 N·m, while a 14mm spark plug requires 25-30 N·m for tightening. More information about spark plugs is as follows: 1. The ignition performance of spark plugs directly affects the performance of a car's engine. If the ignition performance is poor, it may not only cause difficulties in starting the engine and make the car feel sluggish, but also severely impact the engine's lifespan. 2. After prolonged use, some spark plugs may be difficult to remove. It is advisable to wait until the engine has fully cooled down before attempting to remove them.
I was extra careful about the torque issue when I last changed the spark plugs, because over-tightening can strip the cylinder head threads, which is expensive to fix. Generally, the torque for spark plugs ranges between 10 to 30 Newton meters, depending on your car model—for example, a regular compact car might be around 15 Newton meters. If it has an aluminum cylinder head, you need to be even gentler, while an iron cylinder head can tolerate slightly more tightening. I learned this from the owner's manual, as each engine design varies, and manufacturers have different specifications. Some people ignore the manual and just tighten to 20 Newton meters, resulting in engine oil leaks or cracked spark plugs. Using a torque wrench during installation is the most reliable method—first snug it lightly, then gradually increase the force, avoiding haste. If it's too loose, the spark plug can leak gas, causing misfires and engine shaking. Over-tightening is worse, potentially crushing the ceramic electrode and ruining the engine entirely. If you're doing it yourself, I recommend starting with a lower torque, like 12 Newton meters, and then checking the seal. If you're unsure, it's best to visit a professional shop—they charge reasonably and ensure safety. Regularly inspecting the spark plug condition is also crucial, as improper torque can lead to more carbon buildup.
