Interesting Hemi Camshaft failure analysis

[nwjones18]

Came across this fairly recent failure analysis and though it was a pretty interesting read. Figured I'd share.

https://www.chargerforums.com/threads/answers-5-7l-hemi-camshaft-professional-failure-assay.382357/

 

[skyactiv]

There is a tear down that was posted a few weeks ago from another engine guru that says something else.

 

[Quattro Pete]

Originally Posted by skyactiv
There is a tear down that was posted a few weeks ago from another engine guru that says something else.

This one:
https://www.bobistheoilguy.com/foru...emi-lifter-cam-failure-cause#Post5443245

 

[OVERKILL]

The letter is an interesting read, the guy hawing a made-up grade (7.5W-40) with a billion ppm of ZDDP? Not so much.

The conclusion that the lubricant is inadequate doesn't make sense, given that as he noted, the valve spring pressure isn't overly high and it isn't a solid roller racing engine. Guys have experienced the issue even on engines run on much heavier additized oil, like M1 0w-40 for example.

I questioned, in one of the other extensive threads on this topic, whether the spring pressure was actually becoming inadequate once the engines got some miles on them, allowing valve float, damaging the rollers, causing them to spall the lobes and eventually lock up.

Roller motors are not supposed to have lofty oil AW requirements, that was one of the reasons they were introduced.

Per the analysis, something is causing the rollers to skid, spall, and eventually lock up and it isn't a lack of lubrication. It could be valve float, defective needle bearings in the rollers or insufficient lifter alignment control, allowing the rollers to scrub due to the body rotating. In any instance, a production street engine with a pretty mild cam shouldn't require Top Fuel levels of AW additives just to keep a cam in it. Given that most of the failures are 2015 and earlier and the lifter part #'s changing multiple times at this point, I expect FCA has/had a pretty good handle on the cause, as did/does GM, who experienced a nary identical issue with their AFM engines.

 

[FlyNavyP3]

I had to stop reading the first thread when someone was touting their own 7.5W40 and talkimg about all their oils having 3000-7000 ppm Phos.

 

[Imp4]

Originally Posted by FlyNavyP3
I had to stop reading the first thread when someone was touting their own 7.5W40 and talkimg about all their oils having 3000-7000 ppm Phos.

Sometimes you just need to know when to walk away.

Cue the Kenny Rogers...

 

[SpitFire6]

Originally Posted by Imp4
Originally Posted by FlyNavyP3
I had to stop reading the first thread when someone was touting their own 7.5W40 and talkimg about all their oils having 3000-7000 ppm Phos.

Sometimes you just need to know when to walk away.

Cue the Kenny Rogers...

Eat some roasted chicken?

 

[bullwinkle]

Originally Posted by Imp4
Originally Posted by FlyNavyP3
I had to stop reading the first thread when someone was touting their own 7.5W40 and talkimg about all their oils having 3000-7000 ppm Phos.

Sometimes you just need to know when to walk away.

Cue the Kenny Rogers...

Know when to hold 'em, know when to fold 'em...

 

[nwjones18]

I know posting anything on this is pretty much like posting a Gov't conspiracy theory.. I've seen that video on the other thread and his theory is lack of lubrication especially at idle.. As a hemi owner I really need to quit reading on the subject and just stick to decent oil change intervals with synthetic I may do an oil analysis when I change this year, but there doesn't really seem to be any surefire way to prevent it happening if its going to.. Mine only has 37k on it and I do get an occasional start up tick that keeps it on my mind.

I also thought you all would enjoy the dude with the crazy boutique oil that would totally prevent any hemi cam failure.. haha

 

[Kestas]

Originally Posted by OVERKILL
The letter is an interesting read, the guy hawing a made-up grade (7.5W-40) with a billion ppm of ZDDP? Not so much.

The conclusion that the lubricant is inadequate doesn't make sense, given that as he noted, the valve spring pressure isn't overly high and it isn't a solid roller racing engine. Guys have experienced the issue even on engines run on much heavier additized oil, like M1 0w-40 for example.

I questioned, in one of the other extensive threads on this topic, whether the spring pressure was actually becoming inadequate once the engines got some miles on them, allowing valve float, damaging the rollers, causing them to spall the lobes and eventually lock up.

Roller motors are not supposed to have lofty oil AW requirements, that was one of the reasons they were introduced.

Per the analysis, something is causing the rollers to skid, spall, and eventually lock up and it isn't a lack of lubrication. It could be valve float, defective needle bearings in the rollers or insufficient lifter alignment control, allowing the rollers to scrub due to the body rotating. In any instance, a production street engine with a pretty mild cam shouldn't require Top Fuel levels of AW additives just to keep a cam in it. Given that most of the failures are 2015 and earlier and the lifter part #'s changing multiple times at this point, I expect FCA has/had a pretty good handle on the cause, as did/does GM, who experienced a nary identical issue with their AFM engines.

Agreed. I used to do camshaft failure analysis for the automotive industry. I don't see how the author can so categorically pinpoint the failure on lube choice. Overkill covered it pretty well. There are so many factors that can affect cam lobe wear. On one design I was involved with, the overhead cam was the last to get oil on startup. This resulted in a design change to include an anti-drainback check valve in the engine. Another problem can be poor break-in from insufficient phosphate coating. Half the author's report was spent talking about his qualifications.

 

[stroked93]

There would be nothing wrong with doing lifters at 75k as a preventative measure.

 

[Silverado12]

Except you would have to take the heads off on both a Hemi and LS motor. Major undertaking.

 

[OVERKILL]

Yup, exactly. And the failure rate is actually extremely low.

 

[caprice_2nv]

It would make more sense financially to swap a used motor in it you had a lifter failure in an LS. For a Hemi maybe not so, my neighbor spun a rod bearing in his 2008 Hemi truck, had to put a used engine in and it took him a while to find one and it cost him around $2000+.

I paid $200 for my spare 5.3.

 

[OVERKILL]

Yup, agreed.

 

[mk378]

I read about 3 pages of that, so maybe I missed the conclusion. The car owner is skeptical if the supposedly independent machinist guy exists at all, or is just an alter ego of the oil salesman. I would tend to agree.

Is "7.5W-30" what you get when you mix half and half 5W-30 and 10W-30? I think we've all done that.

 

[caprice_2nv]

7.5w30 is just a made up thing. It's 5 or 10.

I think the conclusion is defective lifters from the supplier for both Hemi and LS engines. If modern oils with normal zddp can protect my flat tappet camshafts in my daily driven old cars for several years now, they will be fine with any roller camshaft and lifters. If they're defective, I don't think anything will prevent failure.