3.6 Cam Self destruction

[DC3]

I realize there have been an increasing amount of these cam-related posts circulating the forums and FB groups. I am starting this thread to share my experiences and insights from the many posts I have been following.

I started experiencing the misfire issues at around 24k miles on a 2020 with a build date of Sept 2019. I swapped the cams and solenoids and after about ~5k miles, I have the same symptoms on Bank 1 with tick and misfire code. I have not pulled the valve cover but the symptoms are unmistakable from the first round (I have misdiagnosed things before )

I believe there is an issue with the oil channels in the head that get progressively worse over time preventing the necessary pressure to activate low-lift condition.

The rest of this post contains my findings from the 1st swap. I am now trying to decide if I swap the heads or throw in a long block. Alternatively, I am also considering just taking it to the dealer for diagnosis but I have never had a good experience, coupled with my supercharger is a risky proposition. I have decided to fix this right and then sell the truck. I love the supercharger torque but done with 3.6 foolishness. I think I am going with the diesel, yes I know I may be trading one devil for another.

I will continue to update this thread as I venture deeper into the situation.


I swapped the cams and found the bank 1 lobes to be consistently ground whereas bank 2 was more erratic.

There has been some assessments that Jeep installed the exhaust lash adjusters on the intake cams. Based on my tear down, this is not the case. The lash adjuster part numbers have been updated to a new rev and look different than the old adjusters. But there is no way the exhaust lash adjusters would work on the intake side. The height is just too different. The exhaust adjusters also have no oil paths whereas the intake does.

Lash adjuster photo:

The following is an approximation of the wear by lobe:

Bank 1:
Controlled by front solenoid

Cylinder 1 V1: 2.0 mm​

Cylinder 1 V2: 1.6 mm​

Controlled by rear solenoid

Cylinder 3 V1: 1.7 mm​

Cylinder 3 V2: 2.0 mm​

Cylinder 5 V1: 1.9 mm​

Cylinder 5 V2: 1.9 mm​

Bank 2:
Controlled by front solenoid

Cylinder 2 V1: 2.0 mm​

Cylinder 2 V2: 0.06 mm​

Controlled by rear solenoid

Cylinder 4 V1: 0 mm​

Cylinder 4 V2: 0.12 mm​

Cylinder 6 V1: 1.4 mm​

Cylinder 6 V2: 1.6 mm​

Bank 1 Intake Cam

Bank 2 Intake Cam

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[Hootbro]

Thanks for posting. This is some good data.

 

[chorky]

This is great to see some actual numbers.

 

[Minty JL]

Wow those cams are hot trash

 

[Lunentucker]

Outstanding information!
Makes you really wonder how much of this Jeep knows and if they're just hedging their bets on expensive fixes on a huge scale.

 

[DC3]

The wear pattern along the cam is really puzzling. It does not align with solenoid control circuits. It's as if the control channels aren't enabling the same oil pressure across all lash adjuster pockets.

I am tempted to get the adapter to test oil pressure at the solenoids to understand if they are receiving the necessary pressure.

While I don't mind the diagnostic journey, I am most interested in finding a final repair. Rather than swapping cams every 5k miles or heads, etc

VVL Oil Circuit

 

[SPED1]

Say what you want but ever since this happened:
Crane Technologies Group Inc., of Daytona Beach, Fla., has been acquired by Mikronite Technologies of Eatontown, N.J., which provides technology and parts for the aerospace, automotive, commercial and medical fields, according to a recent press release. The acquisition will take place within 60 days, subject to shareholder approval.
Crane Technologies Group Inc., of Daytona Beach, Fla., has been acquired by Mikronite Technologies of Eatontown, N.J., which provides technology and parts for the aerospace, automotive, commercial and medical fields, according to a recent press release. The acquisition will take place within 60 days, subject to shareholder approval.

Crane will continue its operations at 530 Fentress Blvd., according to the press release, and the Mikronite company may move some of its operations and employees to that famous address in Daytona Beach. Present Crane employees and the customers they serve are not expected to be affected by the purchase, the press release said.

The Mikronite company has been involved with Crane Cams for more than a year, and its Mikronite metal finishing process has been used on a variety of Crane hi-po performance parts since then. Mikronite, says the press release. The purchase will provide Crane Cams with more than $8 million in cash equity and equipment-related financing, the release says. Jeff Coats, CEO of Mikronite, will become president and CEO of Crane Cams, while Gene Ezzell, CEO of Crane Cams, will become president of Mikronite Automotive Technologies and will develop new automotive and industrial businesses for Mikronite. --- Dale Wilson
OEM and aftermarket camshafts just have not had the hardness of the older stuff. Blame the oil having less and less zinc by all means too but I still see cams eaten using high zinc content oil.

 

[Charles 236]

I had to replace a right intake camshaft on a '22 Grand Cherokee 3.6 this week. It had one high lift intake lobe wiped out, another one just starting to wear. I believe that the heat treatment of the rockers may be partly to blame for these failures. If there were an oil supply problem, the rollers on the same rocker should show signs of oil starvation, and there are no signs of this happening. Also coming into play is the fact that the high lift section of the rocker does not rotate like the old cam in block flat tappets did. They always have the same contact with the camshaft on each revolution. This would definitely accelerate wear. Just my observations, but I have worked on thousands of engines, including several hundred 3.6 Pentastars, so I have some experience with the failure points of different engines.

 

[ShrimpHappens]

I've read unconfirmed "Pentastar engineer says" that the engine needs periodic WOT and redlines to get oil everywhere it's supposed to go.

Does your driving style correlate one way or another with this?

 

[21Moja]

I've read unconfirmed "Pentastar engineer says" that the engine needs periodic WOT and redlines to get oil everywhere it's supposed to go.

Does your driving style correlate one way or another with this?

I have wondered if this engine simply wants to be abused once in a while...Its a shitty way to build a motor but driving it like you stole it might have some merit.

 

[DC3]

I had to replace a right intake camshaft on a '22 Grand Cherokee 3.6 this week. It had one high lift intake lobe wiped out, another one just starting to wear. I believe that the heat treatment of the rockers may be partly to blame for these failures. If there were an oil supply problem, the rollers on the same rocker should show signs of oil starvation, and there are no signs of this happening. Also coming into play is the fact that the high lift section of the rocker does not rotate like the old cam in block flat tappets did. They always have the same contact with the camshaft on each revolution. This would definitely accelerate wear. Just my observations, but I have worked on thousands of engines, including several hundred 3.6 Pentastars, so I have some experience with the failure points of different engines.

There could be oil starvation to the yellow channels (shown above) which control the low-lift pin retraction. The oil restriction could be from a casting issue and/or blockage from channels simply being too small. I doubt the channels are designed too small, if they were this would be happening on every 3.6.

The lash adjuster and other oilers could be receiving acceptable oiling but the port for the 2nd step activator is now.

There is no doubt the non-roller contact surface is a terrible design. I figure the engineers didn't expect the engine to run in high lift mode all that often so they skimped on the High lift wear surface.

This is an excerpt from the diagnostic tech guide. I tried running the VVL test sequence with my Micropod II but the sequence would error out each time.

 

[WILDHOBO]

I have wondered if this engine simply wants to be abused once in a while...Its a shitty way to build a motor but driving it like you stole it might have some merit.

I had a 2 stroke, three 2 barrel carb, 3.0 liter v6 mercury outboard for many years. It was absolutely happiest at 5,000 rpm’s. People with those engines that babied them to keep gas consumption better had engines that didn’t last as long. If it didn’t run hot as hell, the oil recirculation system didn’t work as well.

 

[Rusty PW]

I've read unconfirmed "Pentastar engineer says" that the engine needs periodic WOT and redlines to get oil everywhere it's supposed to go.

Does your driving style correlate one way or another with this?

I've heard the same thing of the 5.7 Hemi's, that you have to run the shit out of them. They have been known for cam wear. Lack of oiling.

 

[ShadowsPapa]

I've read unconfirmed "Pentastar engineer says" that the engine needs periodic WOT and redlines to get oil everywhere it's supposed to go.

Does your driving style correlate one way or another with this?

That makes zero sense. Think about it - it would mean every single drive, every trip. Oil supply has to be constant, not "let's rev it today to get oil where it is needed". No way. Those who suggest that out there aren't engine people, nor do they understand lubrication.
Once the pressure is gone, the oil film is reduced from the pressures applied to it and after a short time, the protection is gone.
The laws of hydraulics also apply - 30 psi is 30 psi.

(glad someone found the image I posted useful - it's been out there for a while but people still toss out guesses instead of looking at the actual design like is happening now, finally)

The way this works is that if the PCM through self-testing sees that any rocker is stuck on high lift mode, it drops them all into high lift mode. It won't allow only one to operate that way.
That being said - why wouldn't the left bank also have the exact same issues?
Could be a difference in oil supply.

As far as lash adjusters in the wrong holes - a couple of people I trust totally in these engines showed what he found and yes, they were messed up in his engine.

 

[ShadowsPapa]

I've read unconfirmed "Pentastar engineer says" that the engine needs periodic WOT and redlines to get oil everywhere it's supposed to go.

Does your driving style correlate one way or another with this?

If this were true, my wife would need a new engine every few months.
It absolutely makes no sense. It's internet lore, IMO, urban legend if you will.
It would require you to drive it that way constantly, every trip, all the time.
Sounds like those AMC folks who insist an oil bypass line is needed to keep oil to the rear mains - a guy did testing on a dyno proving them wrong, measuring oil pressure and flow through multiple spots in the engine, and yet the believers in the oil bypass line persist, the testing meant nothing.

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