jeepfreek94

No joke, this is the way they came out. The only theories that seem reasonable to me is debris sucked through (recently cleaned throttle body ), or someone didn't gap the plugs. The reason I don't believe the second theory is that I don't think I would of bought the Jeep running like that in the first place. Maybe it was gapped slightly? I've heared that heat causes the gap to get bigger, not smaller. I guess we may never know.

Here is a better picture. Something on top of each piston was striking these two plugs .

ronjenx

Find a bore scope and look at the tops of the pistons.

jeepfreek94

Good idea. I'll do that.

Smizar

Does your engine burn much oil by any chance?

jeepfreek94

No. Does anyone just think the plugs were incorrectly gapped causing them to overheat and the electrode to warp?

Zombie Hunter

OK. I believe it's not a joke now. Please forgive me.

Lets solve this:

1) How many miles have you put on this Jeep after purchase (you bought it used?).

2) Are those plugs Champion RE14PLP5 ?

3) Could you post a pic of the plug straight on of the ground strap? Best quality possible.

4) Did you have a "friend" that could be "messing" with you when you pulled the plugs?


I've changed 1000's of spark plugs in my life time. Most all of them in outdoor power equipment (my job).
I remember one engine, a v-twin Kohler, that came in running on only one cylinder. Spark plug tip beaten flat. I could see marks on the piston top through the plug hole, marks all over it. Pulled the head and found out that a screw that holes the air filter box came loose and ended up in the cylinder. Head, piston and wall beat to poop. This is not the case for you of course.

I've had several that the customer remove an old fouled plug just to replace it with a new plug that the ground strap was flattened. Either they droppped it or it was that was when they bought it. Of course it did not run if it was a single cylinder.

Now the more common, but still rare, on OHV small engines the piston to plug strap is close. So heavy carbon build-up on piston top has closed the plug gap. Noramally this happens slowly at first when the carbon layer comes in contact for the first time. Then as the carbon is built-up and is being packed between piston and plug strap, the process speeds up due to gap closing. On very rare occasions, a tiny piece of carbon will come loose and get in the way and instantly close the plug gap.

Usually the plugs I see in the last quote, are also covered in carbon. Your plugs look good minus the no gap. Look like mine when I changed them at 35,000 miles.

Maybe I'm missing something in the 3.8l engine? I'm suprised it still had the power to get out of it's own way.

-Water in cylinders caused this...no!

-Rods streching...no. (Rods will expand/contract ever so slightly due to thermal reasons. Top-fuel dragsters with aluminum rods can expand up to .010", but the bigger problem is compressing the rods on the power stroke, beating them 'shorter' over time)

If I had to bet what caused it, carbon build up is at the top of the list. As ronjenx said, "Find a bore scope and look at the tops of the pistons." this would be the best.

Keep us updated. I would find out what caused it before it happens again or worse.

jeepfreek94

Zombie Hunter,

Here are answers to your questions:

1) How many miles have you put on this Jeep after purchase (you bought it used?).

I was wrong on my mileage, I'm at 85,493 and i bought at 76,141 so I've put 9,352 miles on it so far.

2) Are those plugs Champion RE14PLP5 ?

Yes they were. I replaced with the champion OEM plugs this time too, but will be changing at 30k here on out, because they were such a pain get out. I might upgrade to a more expensive plug in the future.

3) Could you post a pic of the plug straight on of the ground strap? Best quality possible.

I will as soon as I get home from work.

4) Did you have a "friend" that could be "messing" with you when you pulled the plugs?

My brother in law helping me (bigger arms than me), but I personally pulled these two plugs from the engine. So I know he didn't do it.

Again thanks for the help. I'll keep everyone updated.

All of the plugs were fairly clean, but I'll find a bore scope, and get a good look. I'll also get a better picture of the plug for everyone interested. I'm honest when I say it wasn't running very rough. That is the reason I cleaned the throttle body first. Again, it's running great now. I was getting 14 mpg all the time, and now I'm getting 16.2 mpg interstate and 18 mpg below 55 mph, all according to jeep computer. If something on the piston was hitting the plug wouldn't i have a vibration, or knock? It is idling smooth.

Zombie Hunter

from jeepfreek94:
"If something on the piston was hitting the plug wouldn't i have a vibration, or knock? It is idling smooth."

Carbon hitting the ground strap over time, no knock/vibration.

Carbon contacting between piston top and cylinder head, yes, you would hear a loud knock.

A foriegn loose metal object, such as a small scew, would make a big racket. Once I found a choke shaft screw embedded in the top of a piston on a small block chevy. No noise.

Factory Champion RE14PLP5 Double Platinum are good plugs. Before you decide on a different plug, I would check this forum. Some have had running issues with different brand/type plugs, many costing more than OEM.

I'll keep an eye on this thread to see if any further developments.

Here's a good theory. The previous owner ran crappy/old fuel and never ran over 2500 R.P.M's. You run quality/fresh fuel and run it up to 4500 R.P.M's now and then. Carbon in cylinder is cleaning up and going out the exhaust valve. But a couple of carbon chunks hit your plugs on the way out.

Hey, it's possible.

desync0

Crappy fuel + Alabama heat = detonation. Detonation can can bend the electrode.

Also AL get's crazy rain sometimes, PO could have gotten fuel with water in it.

jeepnsam

Was the engine ever been rebuilt, Replaced a head gasket, or had the cylinder head off at any time?