About a week ago I noticed a rattling noise coming from the engine at low rpm and idle, so I investigated the problem and found that the #1 coil was sitting a little higher than the other coils so I pushed it back down and didn't think too much of it. Just yesterday I went to start it up and it make a loud BANG (probably from the coil hitting the frame) and it started to sound like a V-twin. After shutting it off and looking at the #1 coil, I noticed it was almost completely out off the heads. After pulling it all apart I pulled the #1 coil out to see what was wrong, and the spark plug came with it.

Now, is this a stripped head? Or did i just not tighten down the spark plug enough the last time I put the plug back in? I was able to tighten the plug back down very nicely after removing it from the coil. I haven't started it back up for fear that it will happen again with worse results.

Also, the connection on the coil where it meets the plug is very worn and it sits pretty loose on the plug. Could this have enabled the spark plug to rotate around in the cylinder head and unscrew itself? Or is that unlikely?

 

Not likely, it was either not tight in the first place, or you blew the threads out of the cylinder. I have seen this on cars a few times, and it is repairable. I would take your plug out and take a good look down the cylinder, you may need a mirror and a light. If the threads look bad, or the plug did not thread in and tighten like it should i would get a heli coil kit and fix it before it gets any worse. If the plug went in like it should and the threads look good, then just retighten and you can prolly assume you made a mistake.

 

it sounds like the plug just wasnt tight. Since you got the plug back in and tight.

Did the plug go in easy? if it did, your probably ok. But the suggestion that TK954RR said makes sense too. you can never be too careful.

the other thing I would suggest is to tighten all the other plugs too. if one back out, the others probably will too.

 

Yeah, it tightened down nicely, and i tightened down the other 3 just a little bit to be sure. I'm going to put the coils back today and try running it for a bit.