Back from the dead?

[lloyd3]

I finally got the chance to scope the cylinder on our Montero that was squashing spark plugs. Looks ln there

[b5blue]

WUT.....

[lloyd3]

Sorry, minor crisis had to be addressed here first. Where was I....right. Scoped the cylinder and could clearly see where something had been ingested and smashed repeatedly. Cylinder walls seemed fine but the top of the piston looked like it had a pebble-finish w/chonger-marks all over. Shockingly, the valves were not obviously damaged. This all started in heavy traffic on I-76 passing a truck near the Colorado/Nebraska line last July. I was pushing the car pretty hard to get in front of a line of trucks when it sounded like a valve had failed, causing a big loss of power and a loud whirring/tapping sound. All my dash warning lights were going off as well, so I pulled off of the interstate to side of the road and then limped into Ogallala to put an OBD2 reader on it. The code indicated a misfire on cylinder 6. We assumed it was a coil pack failure but... couldn't get any '06 Mitsubishi parts there so we cleared the codes and tightened the connectors. Surprisingly, this seemed to resolve things, so we kept going. Long story short, it would run ok for a while, then it would throw codes and wouldn't. Two weeks later we got it home from nowhere Minnesota, ordered a coil pack and "fixed" it. The fix lasted a few days and then it ran rough again. Pulled the coil pack and also the plug and saw the electrode on the plug had been smashed in. Replaced the plug with a new one and it ran fine for a week and then smashed the plug again. At this point I figured it was a goner. I put in another new plug, adding an "oil fouling protector" to see if that would protect the new plug. This caused a number of spacing issues for the coil pack mounts and didn't seem to help things a bit. When I pulled the plug to inspect it, it appeared to be damaged again and moreover, the fouling protector had unscrewed from the plug and was now stuck in the head. I gave up, declared the motor "junk", and went looking for a replacement  vehicle. The Montero then sat for 2 months while I dealt with life's many other issues (elections, COVID, work, marriage, kids, etc.). Because we didn't want to invest a bunch of money into a car with a new driver in the house, I purchased a decent (high-miles but well-cared for) replacement SUV and went about making it now serviceable (tires, timing belt, etc.). Fast forward to last Thursday. I had gotten the Montero to start and drive the 50 miles up to my buddy's house (he has the scope used to examine the interior of the cylinder). We managed to get the oil fouler out of the head with a very slim Snap-On socket and proceeded to look things over internally. We found nothing, so we used compressed air to blow some fine metal dust out of the cylinder, bent the electrode back into a semi-proper gap on the plug and put everything back together....and the damn thing runs fine. All the codes cleared, traction control works again, no bad noises, no smoke, nothing.  My best guess now is that when the engine was serviced about a year or so ago (new intake gasket, wires and plugs), a small bolt or nut got into the intake plenum somehow. Everything was fine until I pushed it very hard and long on the Interstate and it pulled said bolt or nut into the cylinder. After mashing said object into dust (& wrecking several spark plugs along the way), it expelled the now small (enough to clear the exhaust valve) debris. Evidently, the nut or bolt wasn't as hard as the piston and head that was used to pulverize it.  Does this make sense to you folks?  Am I good or is this thing going to blow apart later?

[Kern Dog]

I didn't see a picture. If you posted one, it didn't show up for me.

[Mopar Nut]

I didn't see a picture. If you posted one, it didn't show up for me.

  Can't see a picture either if there is one.

[lloyd3]

I didn't post any pictures earlier, but I certainly can...



Near Frostbite Falls, Minnesota...



Smashed plug. The 2 later ones were smashed worse.



Oil fouling protector. My cheap 11/16 socket wouldn't fit down into the valve cover opening to retrieve it when it became detached from the plug.



Our now superfluous 2nd SUV...