Rocker arm issue

[AwCrimety]

Posting as an FYI for those that drive their jeeps gently, but aren't seeing the gas mileage they thought they might.

I took it very easy on my JL for the 1st thousand kilometers. After that, I was passing someone on the highway, and accelerated hard, bringing the engine up to redline. At that point, I started getting flashing check engine light, and an ESS error.

Long story short, I had some bad rocker arms. They've been replaced, and in hindsight, now that it's fixed, it's running way better, and my gas mileage is improved. Used to average 14.x liters per 100km, and now am down to 12. Driving habits haven't changed, just the engine repair.

If your mileage isn't where you think it should be, yet you drive gently, try giving it the beans, and see if you get any misfires. Apparently, these rocker arms have been issue for years on the 3.6, though not common, it is known.

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[jebjkey]

my rocker arms were replaced for the exact same reason. cylinders 2, 4, and 6 intake and cylinder 4 exhaust. Mine had 350 miles when I first noticed and 400 when I took it in.

 

[ALRUI]

my rocker arms were replaced for the exact same reason. cylinders 2, 4, and 6 intake and cylinder 4 exhaust. Mine had 350 miles when I first noticed and 400 when I took it in.

What exactly goes wrong with the rockers? Curious...

 

[AwCrimety]

 

[AwCrimety]

I think they're bad from the factory, not that they go bad

 

[jebjkey]

All the paperwork says is "seized"

 

[AwCrimety]

I dunno, maybe they do go bad then.

 

[ALRUI]

Seems the part should move "freely" when assembled, I'm betting they arent checking them at assembly as the picture used looks like one youd see in a quality alert for assemblers. (though I would have used RED for the "bad" arrow!).

 

[WXman]

Jeep Informant on YouTube has posted pictures of a ruined 2018 due to this, and another user on YouTube is posting videos of his new Rubicon JL being in the buy back process due to engine failure and I guarantee it's rocker arms, though he hasn't said that yet.

 

[AwCrimety]

I haven't seen the jeep informant one? Is it ruined because it wasn't caught in time? How likely are the ones that drove this way for 1k before repair are 'ruined'?

 

[WXman]

I haven't seen the jeep informant one? Is it ruined because it wasn't caught in time? How likely are the ones that drove this way for 1k before repair are 'ruined'?

I think the PUG engine that Jeep Informant did a video on had about 3,000 miles on the odometer. They had to do a complete valvetrain job on it. I would say that once the rocker comes apart like that, the damage is done and a full repair will be necessary. If it's driven long enough like that, it could eventually damage the valves and/or allow pieces to fall into the cylinders which could take out a cylinder also. It's something that needs to be fixed ASAP if you have the issue.

There's a video on YouTube of how Pentastar engines are made, and when you see who installs the valvetrain and how they do it, it doesn't really give you a warm fuzzy feeling inside.

 

[ALRUI]

There's a video on YouTube of how Pentastar engines are made, and when you see who installs the valvetrain and how they do it, it doesn't really give you a warm fuzzy feeling inside.

Worse is I believe that video is from the Toledo plant. I had 2 meetings today about issues were having with a Mexico supplier where I work, needless to say when I saw the JL 3.6 is being made in MX I wasnt thrilled! Some say its a newer plant so the tooling is better (thats a possibility).

 

[thefrog]

There's a video on YouTube of how Pentastar engines are made, and when you see who installs the valvetrain and how they do it, it doesn't really give you a warm fuzzy feeling inside.

Just watched that video - what's with the funky blue lights at the end?

 

[wranglerguyman]

Does the CEL light need to come on in order to tell if the rocker arms are bad? Went from 20~21 down to 16~17 all of a sudden. I mean the weather dropped but the weather was cold back in February when I got it and it never went down to 16~17.

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