ramcharger
Dismember
This piston came out of my 4.0L HO Jeep. In all my years as a mechanic, I've never seen a piston damaged like this. The top ring is gone completely, not a trace of it exists. It's as if it had dissolved.
Saw one that bad out of a Buick Grand National once; it had a terrible detonation problem. Cylinder wall was very bad as well. The customer knew it was having problems but drove it anyway.
How much nitrous were you throwing at that?
Is it possible the plug was loose?
LOL! It sure looks like a nitrous destroyed piston, doesn't it? Nope, no N20 on the Jeep.
The plug was tight when I checked it. I'm wondering if it had a bad injector causing it to lean out on that cylinder.
It might be cheaper to just find another motor out of a wreck?Just a thought.Good Luck!
Hard to say if it was to lean, all the oil that piston was passing kind of mudles up the color issue, white exhaust valve is normal. Could have just been a faulty piston.
Terry
Wow.....sorry to hear this ramcharger. :scratch:
I hate opening "cans of worms", but glad you found the problem with the Jeep and am confident you can make it right. :thumbup:
Just got done putting a new engine in a '92 Laredo. Same thing wrong with piston in the original. Made noise forever but kept running. I did everthing to that engine to try to stop it from making noise including new rockers on the bad cylinder, new cam, new lifters, cleaned all the pushrods. Finally a small part of the piston lifted enough to hit the head and it really started to pound. That was it for it. It made noise when I bought it at the start of our sons college and lasted through his masters before it let loose. I usually associate the 4.0 as a good engine as our other '92 went 317,000 before we just burned out on drivng it and gave it to one of our daughters. It still got 18.2 mpg, same as new, and never used any oil. I changed the oil in it 109 times, and the rear seal every 100,000 to 120,000 miles because of leaks. If I remember correctly it was number four cylinder that had the bad piston.
Ouch#-o That's something you didn't need to see Joe:sad1:
I'm workin' on a guy's Cavalier that he just bought. He dove it for a couple hundred miles and noticed he was losing power.
I told him that loose spark plugs like to make holes in pistons:angry7:
I can pull off the oil filler cap feel the suction and pressure from the two cylinders:toothy10:
could they of..you know forgotten to put that ring on there..im sure that happens every so often..
I never did try to figure out what the problem was. Just junked the engine when I saw the damage to the top of the piston. Could have been a spark plug problem,or maybe even a ring gap (too large or small) problem. Don't know, but I bet someone on here may have a little more imput for you so it doesn't happen to you again. Just so you know, the 4.0 head will fit the earlier carbureted models with a major gain in hp, if you go the short block route and find an older one. Who knows, they may even be less money. Just do a little research on it to make sure you mix and match correctly.
wow, talk about FUBAR'ed! the mysterious disappearing piston ring.
Now you know what was causing the knock. Amazing what kind of damage they will run with.
wow that's buggered up bad, good luck on the rebuild!!