Will the Car Shake If the Spark Plugs Are Not Tightened Properly?
3 Answers
If the spark plugs are not tightened properly, the car will shake. Therefore, when replacing spark plugs, the torque applied should be based on the required torque for the specific spark plug being used. Different sizes of spark plugs require different levels of torque. Steps for replacing spark plugs: Open the hood, lift the plastic cover of the engine, and remove the high-voltage ignition wires. Mark the position of each cylinder to avoid confusion. Use a spark plug socket to remove the spark plugs one by one. While removing them, check for any external debris such as leaves or dust and ensure everything is cleaned thoroughly. Place the new spark plug into the spark plug hole, hand-tighten it a few turns, and then use the socket to tighten it further. Reinstall the high-voltage ignition wires in the correct firing order and secure the cover. Spark plug replacement intervals: Under normal maintenance conditions, spark plugs should be replaced every 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine type, so it is recommended to follow the owner's manual. The following standards can be used as a reference for maintenance and replacement: Platinum spark plugs should be replaced every 40,000 kilometers, standard nickel alloy spark plugs every 20,000 kilometers, and iridium spark plugs every 60,000 to 80,000 kilometers.
A loose spark plug can indeed cause car shaking, especially noticeable at idle. As a frequent mechanic, I've seen many similar cases. The reason is simple: a loose spark plug leads to poor cylinder sealing, allowing compressed gas to leak out, resulting in unstable ignition—when one cylinder malfunctions, the entire engine shudders like it's missing a leg. If left unaddressed for long, fuel consumption may increase, power output weakens, and even the cylinder head threads can wear out, costing more to fix. I've handled cases myself where customers complained of severe shaking, and upon inspection, found the spark plugs weren't tightened to the standard torque. So, when replacing spark plugs, always use a torque wrench to ensure proper tightening and avoid cutting corners. Also, don’t neglect regular maintenance—have the technician test cylinder compression to catch issues early.
I've been driving for over a decade and personally experienced the shaking caused by loose spark plugs. Once after changing spark plugs, I didn't tighten them properly. When starting the car, the entire cabin felt like it was shaking, and even at red lights, the engine sound trembled. Later, upon self-inspection, I found that the excessive gap in the spark plugs caused delayed ignition, unsealed compression gas, leading to misfiring. Such issues are often mistaken for idle motor or air filter blockages, which can be misleading. Fortunately, I fixed it in time. After tightening the screws, the shaking disappeared, and the car ran much smoother. I recommend car owners not to be careless when replacing parts themselves. After tightening, start the car to test and observe the dashboard or feel for body vibrations. Prevention is better than dealing with problems afterward. Regular maintenance can keep your beloved car running more steadily.
