is it possible for a spark plug to come loose overtime,
Yes.
Tester
Yes, it usually means it wasn’t torqued in to the proper spec when it was installed. Sometimes it is under torqued and works loose. Sometimes it is over torqued and the stripped threads are weakened and eventually the plug pops out.
There is a lot of vibration and pressures on the base of the spark plug, so sure it can come loose. But it means someone messed up in some way, it shouldn’t happen.
Yes…but unlikely…Usually the longer they’re left in the more unlikely they’ll work themselves out…in fact they may be very difficult to remove if left in for a long time…That’s one reason I don’t like the 100k mile spark-plugs.
Simple, don’t let it go for 100,000 miles. I change mine every 60K, even though the manual calls for 100K. By 60K, they look completely worn.
spark plugs come with crush gaskets around the base (at the top of the threads), and if they are omitted when the plug is installed, the plug is more likely to work lose.
Yup…same here…
Lots of good points here. Here’s one more. Do not reuse plugs. That crush washer that Ignoramus mentioned is a one-time use. Once crushed, it will not then reform if the plug us reused, and the integrity of the plug installation may be compromosed. Do not pull the plugs, check them, and reistall them as some do. Use new plugs.