Hey yall, I'll start off by saying I know this isn't a jeep forum, but I have the 5.7 hemi and I think someone here would most likely know more about the 5.7 than the Jeep forums. That was my thought anyway. my issue is strictly a hemi engine issue.

Also, I have been a longtime forum lurker on multiple forums and this is my first time ever posting on a forum anywhere, only because I have such a unique problem.

I bought a 2006 commander with the 5.7 hemi from an alleged mechanic about 2 years ago with 187,xxx miles and he said he replaced the engine recently. I even saw the paperwork. The gist of it is that the Jeep he sold me had a bad engine. I didn't know it, but I found out about it about a month or two later when the oil (that he probably just changed) started looking milky-headgasket? The warranty on the new engine was like for 10k miles or something from the shop (I cant remember the details exactly) but I do know the warranty was conveniently just expired. The new (used, I assumed?) engine miles was NOT listed anywhere on the engine replacement.

Anyway here's where it gets interesting, the engine would make a loud "clacking" noise, similar to a thrown rod bearing-only much louder. At an intersection people would be looking at me weird. LOL. So I got mad and floored it, and it went away!

I then drove it for a while (5k miles?)and the engine drove fine, plenty of torque, but I was kind of careful. My wife drove it once and she was unaware, and she got "on it" and the clacking noise came back. Again, I floored it, and it went away. This happened twice more.

I realized if I kept the RPMs under 3,500 or so then it was totally reliable and safe (plenty for a hemi on the highway). However about 8 months ago my wife pulled out in front of someone and romped on it and it started violently clacking again, it no power whatsoever and finally died on us. I brought in to a very well known and reputable shop and had them look at it. They charged us $500 and said (this is an actual quote) "the engine is bad". LOL. I figured whatever I don't have $4k for a new engine, I still owe money on it so I prepared to tow it home. I went out, fired it up and floored it. The VERY loud clacking went away, it sounds pretty much normal, and it still drives fine to this day.

A few side notes: it has significant blowby, the headgasket is blown judging by the milky oil, and there's oil coming out of the intake. It's not our primary vehicle. And I just paid it off if anyone wants it.
Anyone have any idea what this would be? I literally have no idea.
Sorry about the long story!

 

Well, headgasket for sure, and possible a valvetrain issue? Maybe..... Possibly a stuck lifter, that 'unsticks' when you romp on it. (oil pressure goes up.) With the contaminated oil though, it's just a matter of time before the bottom end lets loose. It just doesn't lubricate that well with coolant in it.

 

That's true! I didn't consider that I need to change the oil more often due to the coolant contaminants. The rig has awesome AWD for our harsh winters here in WY, so I'm trying to bleed out the life for another winter until I can get a truck (or potentially a new engine). I considered the lifters, but I thought the noise was too loud, however I'm no expert so I wouldn't know. I wish I had a garage to rip it apart.

 

Yeah, working on that kind of stuff outside in winter is zero fun, even less so where you are at.

Given the prices of used vehicles these days, (and new ones as well....) If the rest of the truck is in decent condition, and works good, another motor is a LOT cheaper.