Wife called yesterday and said the Explorer was making an awful noise. I broke it open this morning thinking I had a collapsed lash adjuster on the left bank. In removing it I pulled the #1 and #2 COP's and could see the #2 COP boot was split about halfway up and had exhaust residue. The plug was still threaded in the head.
The thing is the plug was destroyed. The top portion of the insulator was loose and rattling around in the plug base but what worries me most is the bottom half of the insulator that holds the electrode is gone and, I assume, crushed to dust in the cylinder. They are brand new plugs with less than 2,000 miles on them.
I guess the question is what kind of damage might have been done. Is the loud "Stuck Lifter" noise of days gone by caused by the bad plug or damage done by the insulator in the combustion chamber. For those who have spit plugs in the normal way, did it sound like a loud tapping noise when it let go. The idea of a foreign object in the combustion chamber obviously is very troubling. I'm headed down to the auto parts store now to see if they happen to rent some type of borescope so I might take a look inside. Talked to my Dad and he seemed to think the glass insulator would have been pulverized and blown out and I should just throw another plug in and see what happens. The truck still runs albeit with a miss and the loud noise. 162,000 miles and has given no major problems until now.
No luck on an inspection camera anyway. I gotta get the RA cover back in place and button it up and I guess I'll see what happens. I don't know if the exhaust gases seeping past the plug would ruin the COP or not, guess I'll find out.
Well, I finally got it all closed up. Found an additional plug on the left bank with a completely detached insulator. It was intact at least and didn't end up in the CC like the other one. After repairing both of them i fired it up and low and behold I still had a loud tapping. Being frustrated I wound it up to about 3500 RPM hoping to throw something loose and finish it off so I could sell it to the local "you pull it" junk yard but...the noise went away at the top end only coming back at idle and much quieter. Another trip up and down the tachometer and the tapping is gone altogether. I'm glad I found the damaged plugs and I replaced all of them just to be safe but I have no idea what caused my problem. The only thing I can think of is that it was a lash adjuster that had gotten some debris in it and the high revs boosted the oil pressure enough to clear it. Or I could just be full of it, either way I'll take it.