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Intake Cam Failures - Materials, Design, or both?

roaniecowpony

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Mr. Cowpony, you can change the subject to BBQ any time you want. I love BBQ too. A subject much more tantalizing than "duck holders," for sure!
With mother's day around the corner, as always, my birthday comes along too, and I can have any meats I want, as long as I cook it. 🤣 I saw a massive 25lb prime brisket at Costco yesterday. Tempting... Or maybe just some tri-tip, lightly mesquite smoked.
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That "slipper shoe" just pivots up and down from the pin on the end. It's a "plain bearing" pin, if you will. There is nearly no surface speed/minute on the pin surface. It pivots the shoe up to contact the cam lobe, to get into the high lift mode. The high lift mode is the default position for start-up. Oil pressure, from a PCM controlled solenoid, is used to actuate it to the retracted low lift (outboard rollers) position.
Did not know that about it being default at startup for the 3.6 too. Little bit of a tangent - but the 3.6 in my '24 JT makes similar rattly/ticky sounds to my 2.0 on cold start at transition from the high idle for warmup to normal idle and I remember reading something about being able to unplug the VVL solenoid on the 2.0 and it made far fewer of those rattles on cold start during high idle. Wonder if there's something to that noise/behavior with the VVL system at startup and the cam wear in the 3.6. Had I not had the experience with the 2.0 I would have pegged it as classic Pentastar tick. Maybe there's issues with oil pressure draw down? The sound does settle out once at normal idle for 10 or 15 seconds.
 

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roaniecowpony

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Is he a no pork Texan? Do you put mustard in your sauce? :bandit:👿
No, he likes pork. He just claims that brisket is BBQ and not brisket. And yet, when I go to a BBQ joint and I order a plate of BBQ, I am delivered pork. I have to order brisket to get brisket. And now this thread is doomed.

Also, I'm from Eastern NC and I will die on the hill that mustard and ketchup (tomatoes) do not belong in BBQ sauce. ENC vinegar sauce is the appropriate sauce to pair with BBQ. Brisket I am less picky on.
 

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I had cam and rocker failure on my 2020 JLUR 3.6L. The failure occurred on bank 1 over cylinder 3, with the intake cam lobe and rocker being the only parts damaged at 46,000 miles.

I have maintained a 5,000-mile oil change interval using 0w20, but I am considering switching to 5w30 given my location in Northwest Ohio. Additionally, it appears the bank 1 intake cam is frequently back-ordered.

I put a magnetic oil plug in, hopefully there was not a lot of metal in the engine. I first noticed the tick at higher RPM's around 3500.

Jeep Wrangler JL Intake Cam Failures - Materials, Design, or both? PXL_20260310_134700194.RAW-01
 

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Now, there's a thought. Modified rockers to keep them mechanically locked in the high lift mode.
Ok, I'm dumb but intrigued. I understand the basics about high lift vs long duration. What would a constant VVL in high lift mode benefit us on a stock 3.6L? Wouldn't it take a lot more than a basic cam/modified rocker install? And who makes aftermarket cams/rockers for the 3.6L anyway?
 
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It would
Ok, I'm dumb but intrigued. I understand the basics about high lift vs long duration. What would a constant VVL in high lift mode benefit us on a stock 3.6L? Wouldn't it take a lot more than a basic cam/modified rocker install? And who makes aftermarket cams/rockers for the 3.6L anyway?
It would only work/benefit us if the high lift worked on a roller rocker setup, we’d be eating camshafts non stop on these if they stayed in high lift. Plus all the torque tables and neural network (volumetric efficiency) would have to be completely rewritten.
 
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Did not know that about it being default at startup for the 3.6 too. Little bit of a tangent - but the 3.6 in my '24 JT makes similar rattly/ticky sounds to my 2.0 on cold start at transition from the high idle for warmup to normal idle and I remember reading something about being able to unplug the VVL solenoid on the 2.0 and it made far fewer of those rattles on cold start during high idle. Wonder if there's something to that noise/behavior with the VVL system at startup and the cam wear in the 3.6. Had I not had the experience with the 2.0 I would have pegged it as classic Pentastar tick. Maybe there's issues with oil pressure draw down? The sound does settle out once at normal idle for 10 or 15 seconds.
I did a lot of testing on this. The way the system is designed, no matter what we do in the tuning, VVL rockers will always be in high lift on start up until oil pressure reaches the lifters. That could be the mechanical sound we all experience on start up.

Even if you disable high lift in the tune, high lift will still be active for a second on start up since oil pressure is actually required to turn the system off. Because of the backwards way the system works. VVL solenoid ON means it’s in low lift. VVL solenoid OFF means low lift. It’s not like the Hondas and other manufacturers with similar systems that enable high lift by activating a solenoid and routing oil pressure. The exact opposite. Very unique.
 

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No, he likes pork. He just claims that brisket is BBQ and not brisket. And yet, when I go to a BBQ joint and I order a plate of BBQ, I am delivered pork. I have to order brisket to get brisket. And now this thread is doomed.

Also, I'm from Eastern NC and I will die on the hill that mustard and ketchup (tomatoes) do not belong in BBQ sauce. ENC vinegar sauce is the appropriate sauce to pair with BBQ. Brisket I am less picky on.
I won't bog down this tech thread with an explanation of why BBQ is a category of food instead of a specific dish. But you Carolina folks have your head on backwards sometimes.

Back to the topic of Cams. The picture above is similar to others that I've seen from the PUG. And it still makes me question the metallurgy of the cam. Hear me out. Yes, what we see is abrasive wear of the lobe due to lack of lubrication. There is no spalling or pitting which would typically be present when a hardened surface is overloaded. We just see a perfect groove where the slipper wore away at the cam. That to me at least looks like soft metal and lack of lubrication.
 

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No, he likes pork. He just claims that brisket is BBQ and not brisket. And yet, when I go to a BBQ joint and I order a plate of BBQ, I am delivered pork. I have to order brisket to get brisket. And now this thread is doomed.

Also, I'm from Eastern NC and I will die on the hill that mustard and ketchup (tomatoes) do not belong in BBQ sauce. ENC vinegar sauce is the appropriate sauce to pair with BBQ. Brisket I am less picky on.
Yes, the thread is definitely doomed!

The best briskets do not require sauce, you merely lick the juice off your fingers with each bite. That's the real difference between BBQ and brisket. And yes, I mostly eat BBQ/brisket with my fingers (left hand only - like the Kazak's), unless my wife is present.
 

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I did a lot of testing on this. The way the system is designed, no matter what we do in the tuning, VVL rockers will always be in high lift on start up until oil pressure reaches the lifters. That could be the mechanical sound we all experience on start up.

Even if you disable high lift in the tune, high lift will still be active for a second on start up since oil pressure is actually required to turn the system off. Because of the backwards way the system works. VVL solenoid ON means it’s in low lift. VVL solenoid OFF means low lift. It’s not like the Hondas and other manufacturers with similar systems that enable high lift by activating a solenoid and routing oil pressure. The exact opposite. Very unique.
I think that this also is a condition that leads to excessive wear. High lift operation has a steeper ramp I would assume. So defaulting to the steeper ramp during low/no oil pressure instead of the more gradual curve of low lift can't be helping the situation.
 

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Back to the topic of Cams. The picture above is similar to others that I've seen from the PUG. And it still makes me question the metallurgy of the cam. Hear me out. Yes, what we see is abrasive wear of the lobe due to lack of lubrication. There is no spalling or pitting which would typically be present when a hardened surface is overloaded. We just see a perfect groove where the slipper wore away at the cam. That to me at least looks like soft metal and lack of lubrication.
Really is what it looks like
 

azjl#3

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The followers use rollers and a slider like section. Most of the failures are on the slider portion. This leads to a rolling bending metal fatigue failure of the cam. Which points to either a metallurgical problem, lubrication problem, or both.
That would be a design failure to me, should be roller
 

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Yes, the thread is definitely doomed!

The best briskets do not require sauce, you merely lick the juice off your fingers with each bite. That's the real difference between BBQ and brisket. And yes, I mostly eat BBQ/brisket with my fingers (left hand only - like the Kazak's), unless my wife is present.
I'll agree on this - proper brisket doesn't require anything on the side to make the flavor right. But, the outside of the brisket, I don't care if it's a sauce that you turn into bark or a dry rub or what, as long as it's good and juicy.

BBQ, on the other hand, requires vinegar - in proper amounts - to cut the fat of the pork so it's not too greasy, as pork butt is wont to be.
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