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Knock Knock...


lowend1

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I was heading home one rainy night last week when I was suddenly alerted by the always soothing chime of the CEL (2015 CPO R/T 67kmi, V6, AWD). There was no accompanying symptom - no noise, roughness, hesitation, limp/slowing, etc, just a steady CEL. I quickly scrolled through the screens, checking temp, oil pressure and whatnot, but nothing seemed amiss. I continued home (another 15 minutes on the highway), and when I arrived, I shut the engine off and stepped out to check for a loose gas cap or other obvious cause. I restarted the engine and immediately the CEL lit up again. I shut down and went inside, figuring I would have my mechanic check it after the holiday. I started the car periodically over the next few days and the result was the same - it was not driven any further. Today, I decided to take it to get looked at, and upon startup there was a loud knocking sound from the engine. I shut it off and tried again, with the same result. I checked the oil and it was at the SAFE mark. It's always been serviced by the dealer and not due again for another 3k miles. After a short conversation with my local mechanic, I elected not to drive the car and will have it towed the half-mile to his shop in the AM.
So - has anybody ever run into this? I'm sure I'll be finding out what gives soon enough, but just curious...

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any codes that you know of,, you can check by pushing the start button 3 full cycles from off to on for any codes there are videos on YouTube to show how to do it of courses it doesn't show all the codes that could be there.Please report back on what you find out

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10 hours ago, 2late4u said:

any codes that you know of,, you can check by pushing the start button 3 full cycles from off to on for any codes there are videos on YouTube to show how to do it of courses it doesn't show all the codes that could be there.Please report back on what you find out

Will do - it was flat-bedded over to the shop earlier today, before I saw your post. It might take them a couple days to look at it. I don't know why, but I keep thinking rocker issue - a lot of clattering on startup. 

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  • 3 weeks later...

Okay, so an update...
The car wound up sitting at the shop for a couple of weeks while they cleared up previously scheduled work. The mechanic initially heard the rattle/tap/knock and felt some roughness when the engine was running, so they determined that pulling the intake and valve cover(s) would be necessary to assess the issue. When they went to pull it into the shop today, there was no noise, no miss, no performance issues. He asked me to come over and drive it for awhile, which I did. It ran fine, but still had a CEL, which was thermostat-related - apparently a common problem with the 3.6 (he says he sees it a lot on Jeeps). The thermostat issue would account for the original CEL with no symptoms. So that's being taken care of and I'm having them change the oil as well, even though it isn't due yet. We're going to hold off on pulling the intake and VC, because they say a bad lifter/rocker would likely not make a racket and then go silent. I'm still baffled, though. I read somewhere that a cam phaser can suddenly make that kind of noise and then stop just as abruptly. Has anybody had that happen?

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  • 3 weeks later...

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