3.6 Cam Self destruction

[Lunentucker]

The service writer at Superior never tries to explain anything. He leaves it to the mechanic who is working on the car. In one way, that is smart on his part to stay in his lane. But, as you pointed out, the mechanic is backward in his explanation.

Now the new problem is that when I put it under load, meaning trying to maintain speed or conservatively accelerate going up-hill, it goes into a partial limp mode. The stop-start light comes on, making me think it is a voltage sensor type thing. I disconnected the battery overnight and reconnected it this morning and got the same result.

Any thoughts? The dealer had to flash the PCM with the new valve train code. I pulled that flash off and sent it to Magnuson and they sent me a new tune based on the new flash. It installed with no problems. The dealership cleared off any random codes that were still in the system and it drove like a monster half-way home. But the first hill, it limped the rest of the way.

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[JeepingJohn]

No, what he told you makes no sense and he doesn't know what he's talking about.

At over 2800 rpm, the follower (rocker) is on the center section. Not sure where he got the 3500 RPM or whatever. That's way off.
Granted, the low lift outer lobes are worn, but that's the low lift, and what it's using at lower RPM.
I'm showing you a picture from MOPAR STAR tech training documents. I have a feeling I know more than that tech does, but then, that's no surprise, either.

Low lift used at lower RPMs is the purple colored outer lobes.
The inner lobes are the high lift - over about 2800 RPM.

Outer lobes are low lift, low speed operation.

Inner lobe = high lift for higher engine speeds.

I get it- the mechanics are tasked with trying to find explanations or to explain to customers even if they themselves don't fully understand.

Why you saw the misfires and errors at high RPM - especially above 3500-4000 rpm, is interesting.
I wonder why it took out the low lift portion of things - that's been pretty solid on these for the most part.

Dealership just called. On the test drive today, it ate another cam. That is three sets of cams, including the originals. Any thoughts on what could cause that and what I could do to get it fixed? They are done with trying to repair it at this point. They suggested I find a performance shop and have them tear it down completely and rebuild it or that I order a new motor and have it put in.

I am at a complete loss. The only good thing is that they are not going to charge me anything since they could not fix the problem. But I don't have motor swap money and am worried that if a shop takes it apart to rebuild it, they won't be able to fix it either.

 

[seven30]

Does the supercharger get its oil supply from the engine or is it self contained?
Which lobes are damaged intakes or exhausts.

 

[JeepingJohn]

Does the supercharger get its oil supply from the engine or is it self contained?
Which lobes are damaged intakes or exhausts.

I believe it gets it from the engine supply, for what little it needs. It bolts right on top of the motor.

 

[DC3]

Dealership just called. On the test drive today, it ate another cam. That is three sets of cams, including the originals. Any thoughts on what could cause that and what I could do to get it fixed? They are done with trying to repair it at this point. They suggested I find a performance shop and have them tear it down completely and rebuild it or that I order a new motor and have it put in.

I am at a complete loss. The only good thing is that they are not going to charge me anything since they could not fix the problem. But I don't have motor swap money and am worried that if a shop takes it apart to rebuild it, they won't be able to fix it either.

I ran through the same scenario, also three sets of cams. I just finished installing the new engine (Sunday) and I am trying fresh. As much metal as I've seen flowing out with my oil, I decided not to rebuild the motor. I pulled my oil pan before pulling the motor, dropped in a magnet and I took the attached photo. I had 1,500 miles on the oil and 1,500 miles on the previous fill.

I am contemplating the dissection of my heads to determine a cause. My theory has been clogged oil channels which prevent the high lift from deactivating.

@DAVECS1 Is there any chance an OS issue could cause the premature wear of cams? I ruled out the control system since my wear was not correlated to the control valve actuation (high and low wear on the same circuit)

 

[DC3]

I believe it gets it from the engine supply, for what little it needs. It bolts right on top of the motor.

supercharger oil is separate from the engine circuit. The Magnuson has a 80k change interval (or something like that.

 

[@californiajeeping]

I am so glad I traded my misfiring 3.6 for an ecodiesel. This type of failure is absurd.

 

[JeepingJohn]

I ran through the same scenario, also three sets of cams. I just finished installing the new engine (Sunday) and I am trying fresh. As much metal as I've seen flowing out with my oil, I decided not to rebuild the motor. I pulled my oil pan before pulling the motor, dropped in a magnet and I took the attached photo. I had 1,500 miles on the oil and 1,500 miles on the previous fill.

I am contemplating the dissection of my heads to determine a cause. My theory has been clogged oil channels which prevent the high lift from deactivating.

@DAVECS1 Is there any chance an OS issue could cause the premature wear of cams? I ruled out the control system since my wear was not correlated to the control valve actuation (high and low wear on the same circuit)

Did you go with a brand new motor, a rebuilt motor, or a take-off from where someone did a hemi swap? That seems to be the choice I need to make very soon. If you went with brand new, where did you order it from? The dealership says it will take forever for him to get one direct from Chrysler.

 

[DAVECS2]

I ran through the same scenario, also three sets of cams. I just finished installing the new engine (Sunday) and I am trying fresh. As much metal as I've seen flowing out with my oil, I decided not to rebuild the motor. I pulled my oil pan before pulling the motor, dropped in a magnet and I took the attached photo. I had 1,500 miles on the oil and 1,500 miles on the previous fill.

I am contemplating the dissection of my heads to determine a cause. My theory has been clogged oil channels which prevent the high lift from deactivating.

@DAVECS1 Is there any chance an OS issue could cause the premature wear of cams? I ruled out the control system since my wear was not correlated to the control valve actuation (high and low wear on the same circuit)

It is a possibility the calibration could be causing it. If that is the case, it would mean that cam timing tuning is limited to areas that conserve the cam, which would be unknown to anyone but Jeep engineers. This also leaves very few options for making power safely with the supercharger.

The other counter point I have seen, is this failure seems to happen across the board. I have helped many people with stock motors who had this issue. Also all other brands of superchargers I did not do the tune for.

My latest tunes do not make as much power, because I have do e my best to leave cam timing out of it all together. To many issues to rely on that system. You do have to the pressure out at around 2500 rpm or you will pop the motor. So you can have a surgy dead spot off idle or open the exhaust valves.

The latest issue I have seen is recall versions and 21 and up jeep are getting unique calibrations per vehicle of the throttle body pressure drop table. This makes it almost impossible to use a template tune and get smooth operation. You have to build a file for that unique calibration and maintain that table or you get really odd acceleration behavior.

As you can see the 3.6L has really taken the fun out of this endevor

 

[DC3]

Did you go with a brand new motor, a rebuilt motor, or a take-off from where someone did a hemi swap? That seems to be the choice I need to make very soon. If you went with brand new, where did you order it from? The dealership says it will take forever for him to get one direct from Chrysler.

I first ordered a new motor but learned there was more than an 800 unit backlog. I investigated rebuilt options but far too many bad reviews. I found a takeout with less than 1k miles. I did the swap in my garage

 

[seven30]

I ran through the same scenario, also three sets of cams. I just finished installing the new engine (Sunday) and I am trying fresh. As much metal as I've seen flowing out with my oil, I decided not to rebuild the motor. I pulled my oil pan before pulling the motor, dropped in a magnet and I took the attached photo. I had 1,500 miles on the oil and 1,500 miles on the previous fill.

I am contemplating the dissection of my heads to determine a cause. My theory has been clogged oil channels which prevent the high lift from deactivating.

@DAVECS1 Is there any chance an OS issue could cause the premature wear of cams? I ruled out the control system since my wear was not correlated to the control valve actuation (high and low wear on the same circuit)

So is all this ferrous material or is there also alumium in there? Do the lobe failures appear to be more exhaust or intake?

The Hemi had cam failures for quite a while with all sorts of myths being floated. The end cause was lack of splash lube at idle/low rpm due to cams high location in block and oil galllery casting directly below it which was partially shielding it.

These failures have a cause but they are rare which is makes it harder to track down.

 

[DC3]

So is all this ferrous material or is there also alumium in there? Do the lobe failures appear to be more exhaust or intake?
The Hemi had cam failures for quite a while with all sorts of myths being floated. The end cause was lack of splash lube at idle/low rpm due to cams high location in block and oil galllery casting directly below it which was partially shielding it.

These failures have a cause but they are rare which is makes it harder to track down.

Mostly ferrous. This oil report was just before swapping the first set of cams.

The wear occurs on the intake side.

 

[seven30]

I believe JeepingJohn and DC3 both installed superchargers and both experienced multiple cam failures.

What engine operational characteristics occur when a supercharger is fitted.

How do the front main bearings look? Is there a lot of wear due to the extra belt causing oil pressure issues? Ive seen that in the past on older engines.

Another difference is higher cylinder pressure at exhaust open point which is why I was wondering whether the failures seemed to start on exhaust side. Obviously once trash starts circulating in the system its going to spread the damage.

 

[DC3]

I believe JeepingJohn and DC3 both installed superchargers and both experienced multiple cam failures.

What engine operational characteristics occur when a supercharger is fitted.

How do the front main bearings look? Is there a lot of wear due to the extra belt causing oil pressure issues? Ive seen that in the past on older engines.

Another difference is higher cylinder pressure at exhaust open point which is why I was wondering whether the failures seemed to start on exhaust side. Obviously, once trash starts circulating in the system its going to spread the damage.

The inconsistency in wear across the lobes within a cylinder and across cylinders steers me away from believing the supercharger has an impact, beyond the disconnection of the supercharger system from the valvetrain and lubrication.

The TSB referencing the passenger side cam wear reinforces an underlying issue at least with that bank. I understood the software changes were to revise the low lift deactivation for a higher RPM. But I don't understand why that would impact one bank but not the other.

There have been several NA 3.6 engines with the same repeated cam failures and ultimately engine replacement. If those are covered under warranty I imagine we hear less about them. Since the forced induction crowd is warranty-less we are more sensitive and vocal about the issue.

This is my previous post capturing the wear profile from one cam lobe to another. I measured the cam wear with a caliper, so my measurements are imperfect. You could argue that Bank1 wear variation is within the range of measurement error.

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

 

[seven30]

I think if you can measure any wear with calipers its way past failed. Look at lobes that are just starting to fail for surface problems. The rollers should still be good unless they failed first.

The Chrysler hemi cam issues were pretty clearly due to breakdown of the cam surface due to no lube. Its like a raod starting to degrade. A few tiny pits that will be come pot holes and eventually hammer the roller. Once that happens the roller starts skating. For a long time people would see that and assume the roller was the cause. It was the victim.

Use a good eye loop and examine the best cam lobes although they may be damaged by all the trash particles floating around.

I sure you monitored the oil pressure. I note my pressure takes a while to drop down after reving it up. Did yours behave that way?

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