ottos

Tbird, that is truly hella weird. The piston must have come up to meet and greet that plug, i can't think of anything else. Maybe you caught the motor just before blowing.

Maybe try running the motor to mid-RPM or something and check #2 plug and see if gets damaged again. That way you know whether the piston is permanently riding high or there is a foreign bigass object (which you would hear a rattle anyway, so sounds like you ruled that out).

While you have the plug out, check your compression too!

Damn I didnt think i'd see this kinda post from you anytime soon.

AmericanRicer87

did the coil on plug thing get all messed up by the spark plug jumping up and down do to compression blowing it up? This is what happened to me.

oxfordgt

I don't think some of you know how an engine works. The piston can not touch a stock size sparkplug. If it didthen it mean the rod came off of the crank or the rod seperated from the piston. If either of those happened the engine would not run fine after you regap the plug. Something is in the chamber get a bore scope and find it. It can also jump cylinders on a NA engine so if you dont find it in the #2 cylinder then check 1,3,4. Don't worry about 5,6,7,8 it cant jump sides.

ottos

Some of us... you mean me then right? So i give a long shot theory and that means i dont know engines? I was gonna agree that a foreign object seems more likely but he'd hear something. And a 4.6 2V the clearance is pretty tight between the the piston and spark plug. Anything's possible as tight as it is.

Any noises heard, Tbird? Check the oil for metal?

oxfordgt

The object can be as small as a match head to do that to the sparkplug and no you would not hear that. The clearence is tight but the piston would contact a valve long before it hit the sparkplug.

tbirdscwd

No noises. Haven't pulled the plug on the oil yet, but I pulled the dipstick and there was no shavings or discoloration in the oil. The only thing I can think of is that I had some detonation and a small piece of the piston broke off and stuck to the spark plug, then on the next upstroke it bridged the gap between the plug and the piston. Whatever it is, its most likely out of the cylinder by now, But I'm gonna get a bore scope in that entire bank and make sure. It'll be interesting to see the top of that piston too.[&:]

I took it out and drove it a few hours ago and there is no stutter, miss, smoke, or anything. I can't think of any other way I would get any size foreign object ingested by my engine. My Maf has a screen right before it, So whatever is in my chamber is from the engine internally. Since the car still runs and hasn't duplicated the problem, I think that rules out blown motor or bent rod. But we'll see what the piston looks like.

tbirdscwd

Trust me, it came as a surprise for me too. I've never had detonation issues. Maybe a ****ty tank of gas, cause my car isn't running lean.

tbirdscwd

I just ordered a borescope through NAPA, they have one in the next town over, so I should have it by tonight. I'll be pulling plugs like its nobody's business tomorrow morning. And seeing exactly how much damage I did to the ol piston. I guess it depends on what I find that will determine where I go from here. It still runs fine though, which has got me puzzled.

texas_stang02

do you have any experience building engines? and i don't mean just bolting heads onto an assembled shortblock. a piston doesn't just decide to "ride high", even with tight tolerances, if a piston comes up and hits a spark plug, you've got damage to the bottom end (broken rod most likely), and the motor isn't going to run fine after that happens (if it runs at all). you'd hear all kind of noise and it would run rough as hell up until the momentit decides to stop running(which probably wouldn't take long). and i agree with oxfordgt, the piston would come in contact with a valve before it hit a spark plug.

ottos

Not if the spark plug sits low as it does on a 2V head.

By "riding high" i meant if the rod stretched or the bearings let go, it would take up the clearance to the spark plug.

So there's 3 possibilities i can think of:
1. foreign object
2. blown rod or crank bearings
3. stretched rod (a possibility since these rods are really skinny and made of Al) which should break really soon

Since my note, sounds like #2 is ruled out. I'm not trying to be an ***. If i'm wrong oh well? Thats what evidence is for which Tbird will get shortly.