Mind you...I feel like this is user error...I installed all new pistons/rings like 5k-ish miles ago. I noticed degraded performance and smoking on deceleration, so I decided to pull the plugs, and found this:



So looks like cylinder #7 is the winner. I did a compression test...almost 0 psi in that cylinder. Pulled the head, then the piston...found this:







How in the world did that top ring overlap itself like that? Also...how did this not completely tear up my cylinder because it's as clean as a whistle?? Waiting for a new piston on order...I'm not a patient person. HAHA

 

What were the rings gapped to?

 

are you sure thats ring material and not piston material melted and smashed against the ring

 

Without doubt two broken/blown piston ring lands. Check out the hole on ring land for the oil control ring.

 

No question of it, the ring ends butted, and blew up the piston.

Root cause: not enough end gap.

That's messed up, with a capital F.

Pure dumb luck. Looks like you need to buy a MegaMillions ticket RIGHT NOW.

 

I’d like to see some good pics of the cylinder. Hard to believe it’s not hurt. Is this a forced induction build?

 

What was this engine built for. NA, NOS or forced induction?

 

Definitely butted the ring lands.

5K miles and the piston has that much build up on it??? Are you consuming oil???

 

I couldn't tell you off the top of my head, but I did do a bunch of research prior to doing all of this and had all the appropriate OEM numbers. It's quite possible I screwed up a measurement on this set of rings though.

 

I'll be triple checking the ring gap when putting this piston in for sure.

 

This was built for my 2004 Jeep Wrangler Rubicon - and I like the throttle (NA build).

 

Yes - it was consuming quite a bit of oil before I decided to rip in to it. I couldn't tell if it was coming from the leak I had, but when I fixed it and it started eating more oil...I figured it was time to go deeper.

 

How does the cylinder wall look???
Was this a standard bore or bored over size???
How do the combustion chambers look on the heads???
How does that rod bearing look???

 

Cylinder wall is smooth - no grooves/etc. Standard bore. Combustion chamber on the head is dirty from the oil burning, but otherwise looks good. Rod bearing looks immaculate - I did all the bearings when I put the new pistons/rings in. I'm generally a "lucky" person...at least that's what I've been told...so I'm just going to go with that and use this as a learning experience.

 

Is there any crosshatch visible in the cylinder?

If you clean the combustion chamber off on the cylinder head and the top of the piston, Do you see any pitting?

 

Also keep in mind that the missing parts of that piston are in the engine somewhere. Even if you’ve located the big pieces, there’s likely smalls somewhere.

 

I would be rechecking all the ring gaps.
Were they file to fit rings?

 

Got it all back together...seems to be running WAY better now.

 

Sounds good.

 

Yup, a V8 runs much better when firing on all 8!!